951S hitting boost saftey mode?
05-17-2009, 05:59 AM
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951S hitting boost saftey mode?
I have an 89 951 that is pretty much stock. New cylinder head and all intake hoses/boots and vacuum lines are stock and new.
I was driving it tonight and when I got on the throttle and boost started to build it felt very inconsistant, surging and everything. I backed off and tried it again and the boost jumped around for a second and then dropped down to the first tick on the boost gauge at WOT.
Now it's staying at low boost everytime I get on it, even after I turn the car off and on.
I'm not TOO familiar with the KLR and DME, but I'm figuring I triggered and overboost sensor and the KLR and cycling valve is keeping the boost low.
Tommorow I will go out and check signal line to the wastegate and the wastegate diapragm for rupture. Hopefully it's something simple like that. I glanced in the engine bay and none of the obvious hoses or lines are cracked or anything.
Anything else to check? After I fix it, so I have to do anything to reset the computer?
everyone loves pics
I was driving it tonight and when I got on the throttle and boost started to build it felt very inconsistant, surging and everything. I backed off and tried it again and the boost jumped around for a second and then dropped down to the first tick on the boost gauge at WOT.
Now it's staying at low boost everytime I get on it, even after I turn the car off and on.
I'm not TOO familiar with the KLR and DME, but I'm figuring I triggered and overboost sensor and the KLR and cycling valve is keeping the boost low.
Tommorow I will go out and check signal line to the wastegate and the wastegate diapragm for rupture. Hopefully it's something simple like that. I glanced in the engine bay and none of the obvious hoses or lines are cracked or anything.
Anything else to check? After I fix it, so I have to do anything to reset the computer?
everyone loves pics
05-17-2009, 06:04 AM
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Under the intake manifold, looking between the manifold "fingers" from the right side of the car, you should see a small beige colored plastic canister with tubes leading in and out of it. This is the cycling valve and it controls the turbo boost automatically. If yours is cracked or any of the fittings have broken or lost vacuum, it may be causing problems. Have a look inside there and poke at the fittings to see if anything is amiss.
On my car, I wasn't getting boost and it turned out someone had previously cracked a ftting and replaced it with a brass insert that was leaking. Ended up replacing the CV and all was good again. Good luck with it.
On my car, I wasn't getting boost and it turned out someone had previously cracked a ftting and replaced it with a brass insert that was leaking. Ended up replacing the CV and all was good again. Good luck with it.
05-17-2009, 06:12 AM
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ugh yeah it's kinda hard to get to. I've pulled it out twice so far when doing the intake manifold stuff and then replacing the head so I know it's not a broken fitting on there.
But do you know which line does what on that valve? (which goes to wastegate, etc)
Another thing is that I recently had the fusebox cover off for a while (stupid) and I washed the car and got a bunch of water in the fuse box. I tried to dry it out but I can see corrosion on some of the relay connections. If I shorted anything in there, could that cause this problem? Or if I shorted any of those relays to the ECU it would just work or not work, right?
But do you know which line does what on that valve? (which goes to wastegate, etc)
Another thing is that I recently had the fusebox cover off for a while (stupid) and I washed the car and got a bunch of water in the fuse box. I tried to dry it out but I can see corrosion on some of the relay connections. If I shorted anything in there, could that cause this problem? Or if I shorted any of those relays to the ECU it would just work or not work, right?
05-17-2009, 06:16 AM
#4
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From the Clark's Garage 951 FAQ:
4.3 Cycling Valve
The cycling valve on the 951 is located underneath the intake manifold. It has three ports. One port is connected to the inlet side of the turbocharger between the air flow meter and the turbocharger, one to the discharge of the turbocharger via a banjo bolt on the discharge pipe to the intercooler, and the aforementioned line going to the wastegate diaphragm. Normally, the cycling valve is "open" which allows the pressure from the turbocharger discharge to be bled back to the turbocharger inlet. This is possible because the port on the cycling valve coming from the turbocharger discharge has an orifice in it. When the cycling valve moves toward the "closed" position, it is closing off the port to the turbocharger inlet. This allows pressure from the turbocharger outlet to pass through the cycling valve to the line going to the wastegate diaphragm. This causes pressure to build up on top of the wastegate diaphragm. When the combined pressure on top of the diaphragm and exhaust pressure against the valve seat overcome the spring pressure in the diaphragm, the wastegate will open bypassing the exhaust flow around the turbocharger thereby limiting boost pressure.
The cycling valve is controlled by the KLR Unit (Knock Regulator Unit). The KLR receives signals both directly and from the DME Control Unit to determine how the cycling valve should be controlled. The chips in the KLR have a boost limit which comes preset from the factory. When the actual boost reaches the computers preset limit, the KLR sends a signal to the cycling valve to close which allows exhaust pressure to open the wastegate. If the cycling valve fails, loses power, or a problem occurs in the KLR unit, the cycling valve will fail fully closed. In this mode boost is limited to approximately 1.2 bar. This is essentially the boost at which the force of the exhaust pressure will overcome the wastegate diaphragm spring pressure.
4.3 Cycling Valve
The cycling valve on the 951 is located underneath the intake manifold. It has three ports. One port is connected to the inlet side of the turbocharger between the air flow meter and the turbocharger, one to the discharge of the turbocharger via a banjo bolt on the discharge pipe to the intercooler, and the aforementioned line going to the wastegate diaphragm. Normally, the cycling valve is "open" which allows the pressure from the turbocharger discharge to be bled back to the turbocharger inlet. This is possible because the port on the cycling valve coming from the turbocharger discharge has an orifice in it. When the cycling valve moves toward the "closed" position, it is closing off the port to the turbocharger inlet. This allows pressure from the turbocharger outlet to pass through the cycling valve to the line going to the wastegate diaphragm. This causes pressure to build up on top of the wastegate diaphragm. When the combined pressure on top of the diaphragm and exhaust pressure against the valve seat overcome the spring pressure in the diaphragm, the wastegate will open bypassing the exhaust flow around the turbocharger thereby limiting boost pressure.
The cycling valve is controlled by the KLR Unit (Knock Regulator Unit). The KLR receives signals both directly and from the DME Control Unit to determine how the cycling valve should be controlled. The chips in the KLR have a boost limit which comes preset from the factory. When the actual boost reaches the computers preset limit, the KLR sends a signal to the cycling valve to close which allows exhaust pressure to open the wastegate. If the cycling valve fails, loses power, or a problem occurs in the KLR unit, the cycling valve will fail fully closed. In this mode boost is limited to approximately 1.2 bar. This is essentially the boost at which the force of the exhaust pressure will overcome the wastegate diaphragm spring pressure.
05-17-2009, 06:18 AM
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Have a read.
6.0 944 Turbo Problems
6.1 Foreword
This section of the FAQ deals with problems that 944 Turbo owners have experienced in the past. This information is taken from the 944 Turbo Problems FAQ which was originally developed by Chris Mellor. There were a number of contributors to the FAQ including Jim Dresser, Chris Hanlon, Clark Archer, Stu (?), Farzaan Kassam, Bob Tucker, and many others.
6.2 Turbo Does Not Boost Correctly
It boosts to a level and will not go any higher
It does not produce any turbo pressure at all
It produces varying boost depending upon the gear you are in. (See 6.2.5 Other Mechanical Problems below - the kinked throttle cable problem.)
Diagnostic Suggestions: Clamp off the line from the cycling valve to the wastegate and drive the car. This will close the wastegate and direct all the exhaust to the exhaust turbine. Now drive the car but do NOT fully depress the throttle. Just go over 3,000 rpm to see if the turbo boost is working. (If it is and you depress the accelerator a lot then the turbo could spin too fast and over-boost the engine causing damage.) If the car then boosts OK it means that the cycling valve and line are where the problem lies. The wastegate is not being controlled properly. This could mean that the cycling valve is being given bad information due to a faulty DME, knock sensor or 'control units' or is faulty itself.
If the car doesn't boost properly then look for:
A mechanical problem with the turbo
A leak or other problem in the air intake system
The wastegate sticking open
A leak in the exhaust system
Other mechanical problems
Engine computer problems
These checks should point you in the right direction.
Other diagnostic checks:
Does the car only boost up to 0.2bar or 1.2bar absolute?
If yes, then it's a likely problem with a connection on one of the various sensors (TPS, airflow meter, etc).
Hook up an after-market boost gauge to get an idea of what the turbo is actually doing. (The turbo could actually be working but a slipping clutch could absorb all the turbo boost and make it seem as if there is no turbo effect.) The after-market boost gauge measures turbo boost pressure before the air enters the intercooler.
6.2.1 Mechanical Turbo Problems
Pull off the turbo intake hose and check for freedom of movement in the turbo. The turbo unit itself may be broken. E.g. the compressor wheel could be broken.
6.2.2 Air Intake Problems
Look for a vacuum leak. A vacuum leak will be a boost leak once the turbo spools up.
Make sure all the vacuum lines are not cracked, corroded or brittle.
Check along the intake manifold system between the pressure side of the turbo and the inlet manifold.
Check the rubber Y-connectors on the intake manifold for leaks.
Look at the rubber connector boost (boot?) on the intercooler pipes,
Check the rubber boot coming out of the turbo to the metal intercooler pipe
Check the compressor bypass valve (air cut-off valve as Porsche call it) located on the rubber boot just before the throttle body. A vacuum line goes to the top of it. If the valve fails and is stuck open, the boost from the turbo will just re-circulate around the turbo and not get to the engine.
A (timing valve fault may cause boost to be limited to
Suggestion: Disconnect the timing valve. It is located between cylinders 3-4 just under the intake manifold. It has three hoses attached to it and an electrical connector at the top. (The top is white). To check if it works, place a stethoscope (automotive) on the top of the valve with the engine running. Then very quickly throttle the car past 60% and listen for a clicking sound on the valve. It sounds like a very fast "blap/blap/blap". You have to do this very quickly because you do not want to over-rev the engine. The valve is controlled by the KLR.
If the intercooler was full of oil or somehow blocked it could limit the turbo boost.
Note. Leaks in the inlet manifold area should trigger a blink code. However, if they are very small leaks then pressure could leak out but the leak not register via the blink code.
Suggestion: Have the Porsche specialist shop force a fault to make the blink code work. E.g. remove the throttle connector and it should start blinking. IF it does that tells you that the KLR is somewhat working.
Check all inlet piping extremely carefully for a leak. Even the tiniest crack will reduce boost to nothing.
Make sure the intercooler is not split, corroded or cracked.
6.2.3 Wastegate Problems
You have to use pressure to make the wastegate open. With the car idling the by-pass pipe should be cold or just a little warm. Use a hand vacuum/pressure pump to check to see it the wastegate is working.
Hook the vacuum/Pressure pump to the wastegate and apply max .5 bar of pressure. The pressure will open the wastegate and release the hot gases into the by-pass pipe.
If the pipe gets warm the wastegate is working.
If the pipe starts out hot then the valve is stuck open.
If the by-pass pipe is disconnected because you are replacing the gaskets (do not start the engine unless all the exhaust is connected.) you can watch the valve open.
There is a membrane controlling the valve so use no more than .5 bar (7lbs) of pressure.
Check proper operation of the wastegate using a vacuum pump.
Check the vacuum hose off the rear of the engine that goes to the wastegate for a leak.
Check that the wastegate is not stuck open.
Check that the wastegate hose is the correct size. If too big it can leak and cause faulty wastegate behavior.
6.2.4 Exhaust System Leaks
Check with a hose type stethoscope. Check there are no exhaust leaks from the header. Make sure there are no cracks in the turbo's exhaust housing. If you have a catalytic converter make sure that it is not clogged.
6.2.5 Other Mechanical Problems
A kink in the throttle cable can stop the turbo from spooling properly. One car car produced 2 bar at full throttle in first gear, but 2nd through 5th would not produce anything. This was because the throttle cable was kinked. The fault also seemed to get worse as the car warms up.
A faulty throttle switch can stop the turbo spooling properly. There could be a bad connection due to corrosion on the throttle position switch (located on the throttle body, forward of the intake manifold). On one side is a cable that controls the throttle opening, and on the other side is a black plastic switch that reads the throttle position. The connection to this device can become corroded. Typically moving around the connector a bit will fix the problem temporarily. Disassembling the connector, cleaning and putting on a coat of dielectric grease on it will fix the problem semi-permanently.
The timing belt may have slipped a tooth and the engine is thus retarded.
An oil trap leak can drop the boost.
Check the cycling valve connections. If they are corroded or broken off, the car will only register 0.2bar (1.2bar absolute) and will give no error codes.
6.2.6 Engine Computer Problems
The 944 Turbo engine is controlled by a Bosch Motronic DME unit. It links to a KLR turbo control unit. If either of these units are faulty then the turbo may not behave correctly. A Bosch diagnostic unit can be connected to the DME box and interrogate it. If the DME has detected a fault it may return a fault code to the Bosch diagnostic system which describes the fault when it is decoded.
A DME unit can perform incorrectly due to broken solder joints and/or broken/bent pins in the plug which connects it to the rest of the engine and its sensors.
A new Bosch Motronic unit is c £1,100 in the UK ($1,000 in the USA?). A re-conditioned unit is c £400. There are service operations, such as Network 500 Ltd in the UK, which diagnose and recondition engine brains.
6.3 More Pronounced Turbo Lag.
Check the vacuum pipe which connects to the top of the air recirculating valve. It is also referred to as the blow-off or pop-off valve. A failure in the valve can cause this pipe to be blown off the valve. The vacuum connector then does not do its work. The valve's function is to prevent a sudden slowdown of the turbine compressor wheel when the throttle is let go. If you then re-accelerate you would have to wait for the compressor wheel to spool up to high speed again - turbo lag. When the throttle is closed (accelerator pedal released) a vacuum occurs in the inlet manifold. This vacuum is detected by the air recirculating valve via the vacuum pipe. This valve opens and causes the compressed air coming out of the turbo to flow back into the turbocharger's air inlet space thus recirculating the compressed air and maintaining turbo compressor wheel speed.
The air recirculating or dump valve is located on top of the large diameter ribbed plastic pipe which goes between the airflow meter unit and the input side of the turbocharger. The vacuum pipe goes between the valve top and a 'T' piece close to the regulator valve on front of the fuel rail.
Testing the valve requires you to remove it. Unfasten two hose clamps, pull off the vacuum pipe and move the valve out and away from the air pipes attached to it. Clean the two air pipe connections on the valve and blow hard down each air connection while feeling for air leaks from the other connections. There should be no leaks. If there are it means that a diaphragm inside the valve has failed. A new valve costs about £20.00.
6.4 Turbo Overboosts
Problem statement: By far the biggest problem (at least so it seams) with my new 951 is that it cuts the fuel VERY abruptly during heavy acceleration. It is almost like someone is hitting the brakes! It usually happens around 4000rpm but will not occur if I just accelerate "normally". Also, my boost gauge is stuck at one when the engine is on (it returns to 0 when engine is turned off). I believe I can hear the turbo spinning during the acceleration so somehow the boost gauge must be connected wrong?
Second Problem statement: The car idles and runs fine, as long as you don't get on the boost hard. If you floor it, the boost gauge goes up to about 1.8, then, a couple of seconds later, the car jerks hard, and the boost goes away (fuel shut off??). I believe that either the cycling valve or the wastegate isn't working. Is there any way to check out which of these 2 items isn't working? Does anyone know of better designed parts to replace these?
Diagnosis 1: This is an overboost situation. One of the most common causes of overboost is the pressure line leading from the wastegate. A crack here will cause overboost for sure the DME then shuts off the fuel. This hose is rubber & can dry rot over time.
Diagnosis 2: You have a broken vacuum/boost line (hose) between the intake manifold between cylinders 3 and 4 and the KLR (Turbo control computer) box in the passenger footwell, or your KLR box is broken. If this hose is somehow cut or is leaking, the KLR will be reading atmospheric pressure, which will result in no real power for you. The KLR doesn't know how much boost, so goes into overboost protection mode (which is the abrupt cutoff of boost.)
Diagnosis 3: One possibility is that the connection to your air flow meter needs to be cleaned. The next is your wastegate is stuck. The next is that you have a leak in your lines going to the wastegate so that it doesn't measure the proper boost from the turbo and keeps letting boost build. Result: your DME/KLR will shut down the fuel so you don't blow your head gasket and you fly through the windshield. Inspect your hoses to and from the wastegate and cycling valve.
6.5 Turbo Pump/Fan Failure
Problem statement: I have a 1988 turbo S and I haven't heard the turbo water pump come on for some time. Temperature on the engine stays on the cool end when running (2nd mark) and goes up to the 3rd mark after the engine is shut off (after the fans have come on). Is the turbo water pump supposed to run for 30 seconds or so, or is it temperature regulated? How should it act?
Diagnosis 1: It should come on period. If it does not you are shortening the life of your turbo. Check it directly by disconnecting the wires and jumping it with a hot it should come on. If not check the relay(G19 on an '86 944 Turbo). If these things do not help then replace the part. Your turbo needs it. I replaced mine ($100) along with all the hoses leading to it. It took the better part of a Saturday but was well worth it.
Diagnosis 2: The turbo water pump should run for ~30 seconds after shut off independent of coolant temp. It is possible that the pump is binding and that loosening the hoses and adjusting things will free it up. Check the 944 FAQ for more on that subject.
6.6 Fitting A Boost Gauge.
Statement: I want to install a VDO boost gauge in my 951. I have it already mounted in the console and now need to do the vacuum line connection.
Response 1: There is a banjo bolt on the intake manifold just above and slightly forward of the cycling valve. The cycling valve is between cylinders 3 and 4, under the intake manifold (round, cream colored about the size of a ½ dollar). This banjo bolt has a vacuum line leading from it, with a T or Y connector (3 way) in the line. I replaced that Y connector with an X connector (4 way) and simply hooked the VDO gauge plumbing to that connector, and reconnected the other vacuum lines to it. You should be able to find an X connector of the proper size at (in the USA) Western Auto or other parts house. You will have to get flexible tubing to connect the hard tubing from the gauge to the X connector.
Response 2: The boost gauge can be hooked up by using a "T" connector to tap into the vacuum line from the intake manifold to the KLR control unit. This nice thing about connecting here is that it minimizes the length of the vacuum line required for the hook up and you don't have to worry about running the vacuum line through the firewall. With the vacuum line on the 944 Turbo, you can use a 1/4" compression fitting. However, it will be a tight fit an you'll have to work at it to get the compression nut and ferrule on the tubing. Most aftermarket boost gauges can be purchased with a hook up kit. They can come with varying sizes of tubing, but most I've seen come with 1/8" hard plastic tubing and usually come with a compression fitting. Be careful when tighten the compression nut for the 1/8" tubing because the 1/8" compression ferrules crush very easily.
6.7 Turbo Pump Stays On When Engine Running
Statement: I cleaned the '87 951 engine compartment today with a pressure hose and as usual something goes awry. The turbo pump now stays on after the car is started. If the relay (G22) is removed (car is not running) the pump will stop after the relay is re-inserted. However the next time the car is started the pump will run on again. Disconnecting and reconnecting the two pin connector has no effect - other than stopping and starting the pump. BTW it is only about 15 minutes after the wash and I am hoping the problem will disappear after everything has dried. I hope the Porsche Gods are listening (compassionately - yeah!).
I have done the following with no effect:
Cleaned the connector contacts (near the shock towers)
Rapped the relay and cleaned the relay contacts
Diagnosis: Sounds like you damaged the thermo switch for the pump. It is mounted into the turbo water pipe, look for a single wire connector with a black Bakelite covering. If you disconnect this switch and the turbo water pump does not immediately start when you turn on the ignition (without starting the engine), then that is your culprit.
6.8 Random Boost Fall Problem.
Statement: I own a 1986 944 Turbo that I bought with 71K miles. Shortly after buying the car I began experiencing problems with the turbo boosting. It will happen randomly and always at a bad time. The problem consists of the turbo only boosting to 1.2 bar rather than the usual 1.8 bar. This becomes extremely annoying while trying to pass on a country road. The problem cures itself when the engine is shut off and immediately started again. I have tried shutting it down and starting several times while coasting into toll booths and I have never had a problem after the restart. About seven months ago I took the car to a Porsche Dealer. The mechanics worked on the car for two hours, which included a few calls to other dealerships. Unfortunately, they could not find the problem. Also has a rough cold idle.
Diagnosis 1: To really nail this down, one would want to do a complete checkout of your exhaust system, consider removing the turbocharger and re-gasket it, and evaluate the waste gate. Putting it on a dyno could help, too, because you could evaluate the exhaust gases at the same time. One reason for the loss of boost can be lack of fuel - leaning - which would be picked up by the sniffer. If fuel were the problem, it could be related to failing fuel pressure regulators on the fuel rail, or a vacuum leak which would compromise the effectiveness of the fuel enrichment system. The frustrating part of this sort of thing is that it is still intermittent, and probably did not show itself to the shop you took it to.
Diagnosis 2: Your problem could be a bad throttle position sensor. The fact that the problem goes away after restart would tend to confirm it. My 87 951 had the same problem early in its life.
Solution: The problem turned out to be the KLR chip.
6.9 Excessive Heat From Intake Manifold
Statement: I have a technical problem. It's a 951 '86, and I just removed the turbo and replaced all seals in the area. Everything runs like a charm, great power and smooth idle. But, I notice rich running and EXCESSIVE heat coming from the intake manifold. At first, I said it was the turbo heating up. But the water temp is not at all high, in fact it just barely simmers at ½ way on the gauge as usual. The intake manifold is so hot it can't be touched after is stops running. The DME is running the mixture rich to cool things down. But what is causing the heat?
Diagnosis 1: Sounds like you damaged the thermo switch for the pump. It is mounted into the turbo water pipe, look for a single wire connector with a black Bakelite covering. If you disconnect this switch and the turbo water pump does not immediately start when you turn on the ignition (without starting the engine), then that is your culprit.
6.10 Turbo Oil Leak.
Statement: My '86 944T produces an oily smell from the exhaust when accelerating moderately-hard. (Although no smoke is visible). There is no smoke/smell at start-up but the first time the engine is revved there is some oil smoke which clears quickly. (This only happens when the car has stood over-night). I suspect oil is getting into the engine from the turbo as the air pipes leading from the turbo charger to intercooler to inlet manifold have considerable oil deposits in them. Puddles of oil are evident at the low points along the route, e.g. at connections in/out on intercooler and at throttle body. If I clean out the pipes the smell goes away for a day but then returns, together with the oil.
The oil is not coming from the breather pipe as I temporarily disconnected it and plugged the hole left in the intake. Leak-down test has shown that all is well with cylinders. The valve guides/seals have recently been replaced during top-end overhaul - it made no difference. The problem has slowly got worse over the past 18 months. I suspect turbo bearing/seal.
Diagnosis?
6.11 Cycling Valve Not Working Properly.
Statement: The cycling valve on my 951 is not working properly. The valve is ok (tested), but it never gets any signal from the computer. The valve should open when the air flap in the air flow sensor swings +60=B0. Since no signal is coming from the computer (wiring and pressure line seem ok), I was wondering what the origin of this problem can be. Apart from a fault in the computer, which sensor inputs can result in no signal to the cycling valve (knock sensor, etc...)?
Diagnosis?
6.12 Turbo Oil Consumption.
Statement: I have found that the more I use my turbo, the more oil I consume, by a big margin. When I first got the car, I drove very conservative and used/lost about ½ qt in 1500 miles or 1 in 3000. When pushing the car a lot, I find that my consumption has been as much as 1 qt in 600 miles. Is this common, or what may be my problem? The car is an 86 turbo with 115k on it, 150 compression across all 4 cylinders. Over boosts also.
6.13 Oil In The Intercooler.
Statement: Should there or should there not be oil in the tubes going to and from the intercooler? There are no puddles just a film of oil on the inside surfaces. Is this normal or an indication that the turbo seals are going bad. This 86 951 has only 50K original miles and I hope a turbo rebuild isn't required just yet.
Answer: It is normal for there to be a light film of oil there. Over time the oil will also coat the intercooler, reducing intercooler efficiency. You will want to want to clean the intercooler out from time to time as the build-up increases.
6.14 Boost Rises Then Falls
Statement: I have a weird problem with my '86 951. As I depress the gas pedal, I see the boost rise, but just when it should give me that power kick, I actually experience a power loss - it feels as though I had downshifted. My current theory is that the boost is somehow not available at the intake manifold, but the onboard computer thinks it is and begins to inject more fuel into the air stream - causing a power loss because the air/fuel ratio gets messed up. But I really fail to see how it is that the boost is not making it to the intake.
Diagnosis: There are several things you can try to fix this:
Unplug the air meter box connector and clean the connector off.
Check for unplugged vacuum hoses
Check the idle speed screw, see if you have one (I don't know if they fall out or just get forgotten)
What is happening I think, and this seems to be a common problem, is that the computer thinks you have an overboost situation and is shutting the fuel down. Now, you may have a real problem. The wastegate may be stuck, the timing valve may not have power etc.., so if you can't find the fix take it to a trustworthy mechanic. It took me a year and several mechanics to actually fix my problem. In the meantime, one had me replace the computers, one told me my wastegate was stuck, "bla bla bla".
Clark's Garage © 1998
6.0 944 Turbo Problems
6.1 Foreword
This section of the FAQ deals with problems that 944 Turbo owners have experienced in the past. This information is taken from the 944 Turbo Problems FAQ which was originally developed by Chris Mellor. There were a number of contributors to the FAQ including Jim Dresser, Chris Hanlon, Clark Archer, Stu (?), Farzaan Kassam, Bob Tucker, and many others.
6.2 Turbo Does Not Boost Correctly
It boosts to a level and will not go any higher
It does not produce any turbo pressure at all
It produces varying boost depending upon the gear you are in. (See 6.2.5 Other Mechanical Problems below - the kinked throttle cable problem.)
Diagnostic Suggestions: Clamp off the line from the cycling valve to the wastegate and drive the car. This will close the wastegate and direct all the exhaust to the exhaust turbine. Now drive the car but do NOT fully depress the throttle. Just go over 3,000 rpm to see if the turbo boost is working. (If it is and you depress the accelerator a lot then the turbo could spin too fast and over-boost the engine causing damage.) If the car then boosts OK it means that the cycling valve and line are where the problem lies. The wastegate is not being controlled properly. This could mean that the cycling valve is being given bad information due to a faulty DME, knock sensor or 'control units' or is faulty itself.
If the car doesn't boost properly then look for:
A mechanical problem with the turbo
A leak or other problem in the air intake system
The wastegate sticking open
A leak in the exhaust system
Other mechanical problems
Engine computer problems
These checks should point you in the right direction.
Other diagnostic checks:
Does the car only boost up to 0.2bar or 1.2bar absolute?
If yes, then it's a likely problem with a connection on one of the various sensors (TPS, airflow meter, etc).
Hook up an after-market boost gauge to get an idea of what the turbo is actually doing. (The turbo could actually be working but a slipping clutch could absorb all the turbo boost and make it seem as if there is no turbo effect.) The after-market boost gauge measures turbo boost pressure before the air enters the intercooler.
6.2.1 Mechanical Turbo Problems
Pull off the turbo intake hose and check for freedom of movement in the turbo. The turbo unit itself may be broken. E.g. the compressor wheel could be broken.
6.2.2 Air Intake Problems
Look for a vacuum leak. A vacuum leak will be a boost leak once the turbo spools up.
Make sure all the vacuum lines are not cracked, corroded or brittle.
Check along the intake manifold system between the pressure side of the turbo and the inlet manifold.
Check the rubber Y-connectors on the intake manifold for leaks.
Look at the rubber connector boost (boot?) on the intercooler pipes,
Check the rubber boot coming out of the turbo to the metal intercooler pipe
Check the compressor bypass valve (air cut-off valve as Porsche call it) located on the rubber boot just before the throttle body. A vacuum line goes to the top of it. If the valve fails and is stuck open, the boost from the turbo will just re-circulate around the turbo and not get to the engine.
A (timing valve fault may cause boost to be limited to
Suggestion: Disconnect the timing valve. It is located between cylinders 3-4 just under the intake manifold. It has three hoses attached to it and an electrical connector at the top. (The top is white). To check if it works, place a stethoscope (automotive) on the top of the valve with the engine running. Then very quickly throttle the car past 60% and listen for a clicking sound on the valve. It sounds like a very fast "blap/blap/blap". You have to do this very quickly because you do not want to over-rev the engine. The valve is controlled by the KLR.
If the intercooler was full of oil or somehow blocked it could limit the turbo boost.
Note. Leaks in the inlet manifold area should trigger a blink code. However, if they are very small leaks then pressure could leak out but the leak not register via the blink code.
Suggestion: Have the Porsche specialist shop force a fault to make the blink code work. E.g. remove the throttle connector and it should start blinking. IF it does that tells you that the KLR is somewhat working.
Check all inlet piping extremely carefully for a leak. Even the tiniest crack will reduce boost to nothing.
Make sure the intercooler is not split, corroded or cracked.
6.2.3 Wastegate Problems
You have to use pressure to make the wastegate open. With the car idling the by-pass pipe should be cold or just a little warm. Use a hand vacuum/pressure pump to check to see it the wastegate is working.
Hook the vacuum/Pressure pump to the wastegate and apply max .5 bar of pressure. The pressure will open the wastegate and release the hot gases into the by-pass pipe.
If the pipe gets warm the wastegate is working.
If the pipe starts out hot then the valve is stuck open.
If the by-pass pipe is disconnected because you are replacing the gaskets (do not start the engine unless all the exhaust is connected.) you can watch the valve open.
There is a membrane controlling the valve so use no more than .5 bar (7lbs) of pressure.
Check proper operation of the wastegate using a vacuum pump.
Check the vacuum hose off the rear of the engine that goes to the wastegate for a leak.
Check that the wastegate is not stuck open.
Check that the wastegate hose is the correct size. If too big it can leak and cause faulty wastegate behavior.
6.2.4 Exhaust System Leaks
Check with a hose type stethoscope. Check there are no exhaust leaks from the header. Make sure there are no cracks in the turbo's exhaust housing. If you have a catalytic converter make sure that it is not clogged.
6.2.5 Other Mechanical Problems
A kink in the throttle cable can stop the turbo from spooling properly. One car car produced 2 bar at full throttle in first gear, but 2nd through 5th would not produce anything. This was because the throttle cable was kinked. The fault also seemed to get worse as the car warms up.
A faulty throttle switch can stop the turbo spooling properly. There could be a bad connection due to corrosion on the throttle position switch (located on the throttle body, forward of the intake manifold). On one side is a cable that controls the throttle opening, and on the other side is a black plastic switch that reads the throttle position. The connection to this device can become corroded. Typically moving around the connector a bit will fix the problem temporarily. Disassembling the connector, cleaning and putting on a coat of dielectric grease on it will fix the problem semi-permanently.
The timing belt may have slipped a tooth and the engine is thus retarded.
An oil trap leak can drop the boost.
Check the cycling valve connections. If they are corroded or broken off, the car will only register 0.2bar (1.2bar absolute) and will give no error codes.
6.2.6 Engine Computer Problems
The 944 Turbo engine is controlled by a Bosch Motronic DME unit. It links to a KLR turbo control unit. If either of these units are faulty then the turbo may not behave correctly. A Bosch diagnostic unit can be connected to the DME box and interrogate it. If the DME has detected a fault it may return a fault code to the Bosch diagnostic system which describes the fault when it is decoded.
A DME unit can perform incorrectly due to broken solder joints and/or broken/bent pins in the plug which connects it to the rest of the engine and its sensors.
A new Bosch Motronic unit is c £1,100 in the UK ($1,000 in the USA?). A re-conditioned unit is c £400. There are service operations, such as Network 500 Ltd in the UK, which diagnose and recondition engine brains.
6.3 More Pronounced Turbo Lag.
Check the vacuum pipe which connects to the top of the air recirculating valve. It is also referred to as the blow-off or pop-off valve. A failure in the valve can cause this pipe to be blown off the valve. The vacuum connector then does not do its work. The valve's function is to prevent a sudden slowdown of the turbine compressor wheel when the throttle is let go. If you then re-accelerate you would have to wait for the compressor wheel to spool up to high speed again - turbo lag. When the throttle is closed (accelerator pedal released) a vacuum occurs in the inlet manifold. This vacuum is detected by the air recirculating valve via the vacuum pipe. This valve opens and causes the compressed air coming out of the turbo to flow back into the turbocharger's air inlet space thus recirculating the compressed air and maintaining turbo compressor wheel speed.
The air recirculating or dump valve is located on top of the large diameter ribbed plastic pipe which goes between the airflow meter unit and the input side of the turbocharger. The vacuum pipe goes between the valve top and a 'T' piece close to the regulator valve on front of the fuel rail.
Testing the valve requires you to remove it. Unfasten two hose clamps, pull off the vacuum pipe and move the valve out and away from the air pipes attached to it. Clean the two air pipe connections on the valve and blow hard down each air connection while feeling for air leaks from the other connections. There should be no leaks. If there are it means that a diaphragm inside the valve has failed. A new valve costs about £20.00.
6.4 Turbo Overboosts
Problem statement: By far the biggest problem (at least so it seams) with my new 951 is that it cuts the fuel VERY abruptly during heavy acceleration. It is almost like someone is hitting the brakes! It usually happens around 4000rpm but will not occur if I just accelerate "normally". Also, my boost gauge is stuck at one when the engine is on (it returns to 0 when engine is turned off). I believe I can hear the turbo spinning during the acceleration so somehow the boost gauge must be connected wrong?
Second Problem statement: The car idles and runs fine, as long as you don't get on the boost hard. If you floor it, the boost gauge goes up to about 1.8, then, a couple of seconds later, the car jerks hard, and the boost goes away (fuel shut off??). I believe that either the cycling valve or the wastegate isn't working. Is there any way to check out which of these 2 items isn't working? Does anyone know of better designed parts to replace these?
Diagnosis 1: This is an overboost situation. One of the most common causes of overboost is the pressure line leading from the wastegate. A crack here will cause overboost for sure the DME then shuts off the fuel. This hose is rubber & can dry rot over time.
Diagnosis 2: You have a broken vacuum/boost line (hose) between the intake manifold between cylinders 3 and 4 and the KLR (Turbo control computer) box in the passenger footwell, or your KLR box is broken. If this hose is somehow cut or is leaking, the KLR will be reading atmospheric pressure, which will result in no real power for you. The KLR doesn't know how much boost, so goes into overboost protection mode (which is the abrupt cutoff of boost.)
Diagnosis 3: One possibility is that the connection to your air flow meter needs to be cleaned. The next is your wastegate is stuck. The next is that you have a leak in your lines going to the wastegate so that it doesn't measure the proper boost from the turbo and keeps letting boost build. Result: your DME/KLR will shut down the fuel so you don't blow your head gasket and you fly through the windshield. Inspect your hoses to and from the wastegate and cycling valve.
6.5 Turbo Pump/Fan Failure
Problem statement: I have a 1988 turbo S and I haven't heard the turbo water pump come on for some time. Temperature on the engine stays on the cool end when running (2nd mark) and goes up to the 3rd mark after the engine is shut off (after the fans have come on). Is the turbo water pump supposed to run for 30 seconds or so, or is it temperature regulated? How should it act?
Diagnosis 1: It should come on period. If it does not you are shortening the life of your turbo. Check it directly by disconnecting the wires and jumping it with a hot it should come on. If not check the relay(G19 on an '86 944 Turbo). If these things do not help then replace the part. Your turbo needs it. I replaced mine ($100) along with all the hoses leading to it. It took the better part of a Saturday but was well worth it.
Diagnosis 2: The turbo water pump should run for ~30 seconds after shut off independent of coolant temp. It is possible that the pump is binding and that loosening the hoses and adjusting things will free it up. Check the 944 FAQ for more on that subject.
6.6 Fitting A Boost Gauge.
Statement: I want to install a VDO boost gauge in my 951. I have it already mounted in the console and now need to do the vacuum line connection.
Response 1: There is a banjo bolt on the intake manifold just above and slightly forward of the cycling valve. The cycling valve is between cylinders 3 and 4, under the intake manifold (round, cream colored about the size of a ½ dollar). This banjo bolt has a vacuum line leading from it, with a T or Y connector (3 way) in the line. I replaced that Y connector with an X connector (4 way) and simply hooked the VDO gauge plumbing to that connector, and reconnected the other vacuum lines to it. You should be able to find an X connector of the proper size at (in the USA) Western Auto or other parts house. You will have to get flexible tubing to connect the hard tubing from the gauge to the X connector.
Response 2: The boost gauge can be hooked up by using a "T" connector to tap into the vacuum line from the intake manifold to the KLR control unit. This nice thing about connecting here is that it minimizes the length of the vacuum line required for the hook up and you don't have to worry about running the vacuum line through the firewall. With the vacuum line on the 944 Turbo, you can use a 1/4" compression fitting. However, it will be a tight fit an you'll have to work at it to get the compression nut and ferrule on the tubing. Most aftermarket boost gauges can be purchased with a hook up kit. They can come with varying sizes of tubing, but most I've seen come with 1/8" hard plastic tubing and usually come with a compression fitting. Be careful when tighten the compression nut for the 1/8" tubing because the 1/8" compression ferrules crush very easily.
6.7 Turbo Pump Stays On When Engine Running
Statement: I cleaned the '87 951 engine compartment today with a pressure hose and as usual something goes awry. The turbo pump now stays on after the car is started. If the relay (G22) is removed (car is not running) the pump will stop after the relay is re-inserted. However the next time the car is started the pump will run on again. Disconnecting and reconnecting the two pin connector has no effect - other than stopping and starting the pump. BTW it is only about 15 minutes after the wash and I am hoping the problem will disappear after everything has dried. I hope the Porsche Gods are listening (compassionately - yeah!).
I have done the following with no effect:
Cleaned the connector contacts (near the shock towers)
Rapped the relay and cleaned the relay contacts
Diagnosis: Sounds like you damaged the thermo switch for the pump. It is mounted into the turbo water pipe, look for a single wire connector with a black Bakelite covering. If you disconnect this switch and the turbo water pump does not immediately start when you turn on the ignition (without starting the engine), then that is your culprit.
6.8 Random Boost Fall Problem.
Statement: I own a 1986 944 Turbo that I bought with 71K miles. Shortly after buying the car I began experiencing problems with the turbo boosting. It will happen randomly and always at a bad time. The problem consists of the turbo only boosting to 1.2 bar rather than the usual 1.8 bar. This becomes extremely annoying while trying to pass on a country road. The problem cures itself when the engine is shut off and immediately started again. I have tried shutting it down and starting several times while coasting into toll booths and I have never had a problem after the restart. About seven months ago I took the car to a Porsche Dealer. The mechanics worked on the car for two hours, which included a few calls to other dealerships. Unfortunately, they could not find the problem. Also has a rough cold idle.
Diagnosis 1: To really nail this down, one would want to do a complete checkout of your exhaust system, consider removing the turbocharger and re-gasket it, and evaluate the waste gate. Putting it on a dyno could help, too, because you could evaluate the exhaust gases at the same time. One reason for the loss of boost can be lack of fuel - leaning - which would be picked up by the sniffer. If fuel were the problem, it could be related to failing fuel pressure regulators on the fuel rail, or a vacuum leak which would compromise the effectiveness of the fuel enrichment system. The frustrating part of this sort of thing is that it is still intermittent, and probably did not show itself to the shop you took it to.
Diagnosis 2: Your problem could be a bad throttle position sensor. The fact that the problem goes away after restart would tend to confirm it. My 87 951 had the same problem early in its life.
Solution: The problem turned out to be the KLR chip.
6.9 Excessive Heat From Intake Manifold
Statement: I have a technical problem. It's a 951 '86, and I just removed the turbo and replaced all seals in the area. Everything runs like a charm, great power and smooth idle. But, I notice rich running and EXCESSIVE heat coming from the intake manifold. At first, I said it was the turbo heating up. But the water temp is not at all high, in fact it just barely simmers at ½ way on the gauge as usual. The intake manifold is so hot it can't be touched after is stops running. The DME is running the mixture rich to cool things down. But what is causing the heat?
Diagnosis 1: Sounds like you damaged the thermo switch for the pump. It is mounted into the turbo water pipe, look for a single wire connector with a black Bakelite covering. If you disconnect this switch and the turbo water pump does not immediately start when you turn on the ignition (without starting the engine), then that is your culprit.
6.10 Turbo Oil Leak.
Statement: My '86 944T produces an oily smell from the exhaust when accelerating moderately-hard. (Although no smoke is visible). There is no smoke/smell at start-up but the first time the engine is revved there is some oil smoke which clears quickly. (This only happens when the car has stood over-night). I suspect oil is getting into the engine from the turbo as the air pipes leading from the turbo charger to intercooler to inlet manifold have considerable oil deposits in them. Puddles of oil are evident at the low points along the route, e.g. at connections in/out on intercooler and at throttle body. If I clean out the pipes the smell goes away for a day but then returns, together with the oil.
The oil is not coming from the breather pipe as I temporarily disconnected it and plugged the hole left in the intake. Leak-down test has shown that all is well with cylinders. The valve guides/seals have recently been replaced during top-end overhaul - it made no difference. The problem has slowly got worse over the past 18 months. I suspect turbo bearing/seal.
Diagnosis?
6.11 Cycling Valve Not Working Properly.
Statement: The cycling valve on my 951 is not working properly. The valve is ok (tested), but it never gets any signal from the computer. The valve should open when the air flap in the air flow sensor swings +60=B0. Since no signal is coming from the computer (wiring and pressure line seem ok), I was wondering what the origin of this problem can be. Apart from a fault in the computer, which sensor inputs can result in no signal to the cycling valve (knock sensor, etc...)?
Diagnosis?
6.12 Turbo Oil Consumption.
Statement: I have found that the more I use my turbo, the more oil I consume, by a big margin. When I first got the car, I drove very conservative and used/lost about ½ qt in 1500 miles or 1 in 3000. When pushing the car a lot, I find that my consumption has been as much as 1 qt in 600 miles. Is this common, or what may be my problem? The car is an 86 turbo with 115k on it, 150 compression across all 4 cylinders. Over boosts also.
6.13 Oil In The Intercooler.
Statement: Should there or should there not be oil in the tubes going to and from the intercooler? There are no puddles just a film of oil on the inside surfaces. Is this normal or an indication that the turbo seals are going bad. This 86 951 has only 50K original miles and I hope a turbo rebuild isn't required just yet.
Answer: It is normal for there to be a light film of oil there. Over time the oil will also coat the intercooler, reducing intercooler efficiency. You will want to want to clean the intercooler out from time to time as the build-up increases.
6.14 Boost Rises Then Falls
Statement: I have a weird problem with my '86 951. As I depress the gas pedal, I see the boost rise, but just when it should give me that power kick, I actually experience a power loss - it feels as though I had downshifted. My current theory is that the boost is somehow not available at the intake manifold, but the onboard computer thinks it is and begins to inject more fuel into the air stream - causing a power loss because the air/fuel ratio gets messed up. But I really fail to see how it is that the boost is not making it to the intake.
Diagnosis: There are several things you can try to fix this:
Unplug the air meter box connector and clean the connector off.
Check for unplugged vacuum hoses
Check the idle speed screw, see if you have one (I don't know if they fall out or just get forgotten)
What is happening I think, and this seems to be a common problem, is that the computer thinks you have an overboost situation and is shutting the fuel down. Now, you may have a real problem. The wastegate may be stuck, the timing valve may not have power etc.., so if you can't find the fix take it to a trustworthy mechanic. It took me a year and several mechanics to actually fix my problem. In the meantime, one had me replace the computers, one told me my wastegate was stuck, "bla bla bla".
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05-17-2009, 06:49 AM
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Great pic, fairly rare color. Very good diagnostic options shared. Odds are very good your problem is among the potential ones listed here. The over boost cutoff occurs occasionally on my 89 also, but that's because I've overridden the cycling valve with an MBC and use a dual port Tial that really does boost beyond the stock chip's threshold. I have hotter chips in my desk drawer, but I'm safer with them sitting right where they are
05-17-2009, 08:09 PM
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It's constantly boosting at .2 bar now all the time.
So my wastegate isn't stuck open, because the wastegate dump is cold, the wastegate line is not leaking and the diaphragm is good.
The cycling valve and the lines to it are not cracked or leaking. It has full battery voltage when the car is running and the resistance across the two terminals is 33 ohms so it's good (supposed to be 18-45 ohms).
When I open the throttle fully, the valve doesn't click though like the manual says it's supposed to. So that leads me to believe either the valve is bad or the KLR is bad.
I'm guessing the KLR..
Does anyone have an extra KLR they want to sell me?
How hard is it to replace?
So my wastegate isn't stuck open, because the wastegate dump is cold, the wastegate line is not leaking and the diaphragm is good.
The cycling valve and the lines to it are not cracked or leaking. It has full battery voltage when the car is running and the resistance across the two terminals is 33 ohms so it's good (supposed to be 18-45 ohms).
When I open the throttle fully, the valve doesn't click though like the manual says it's supposed to. So that leads me to believe either the valve is bad or the KLR is bad.
I'm guessing the KLR..
Does anyone have an extra KLR they want to sell me?
How hard is it to replace?
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05-17-2009, 08:16 PM
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Is there a way to test the cycling valve? I put 12v on the power terminal and grounded the other terminal and it didn't click or anything.
Does anyone have a cyclcing valve they'd like to sell?
I might as well have both an extra cycling valve and an extra KLR to text things out.
Edit:
I just disconnected the wastegate signal line and went for a drive. The car made max boost, but it made it a lot slower than normal and had less power. I'm guessing this is because the KLR is pulling timing as well?
I'm guessing the KLR is the problem..
Does anyone have a cyclcing valve they'd like to sell?
I might as well have both an extra cycling valve and an extra KLR to text things out.
Edit:
I just disconnected the wastegate signal line and went for a drive. The car made max boost, but it made it a lot slower than normal and had less power. I'm guessing this is because the KLR is pulling timing as well?
I'm guessing the KLR is the problem..
Last edited by aventari; 05-17-2009 at 08:35 PM.
05-18-2009, 09:13 AM
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CV testing...
Hey - if you put 12V on the cycling valve manually (as in one connection goes to battery ground, and the other to battery positive connection) and you don't hear a 'click' then there's something wrong with the valve itself. The first time I did this on my valve, nothing happened. I tapped the ground lead onto the battery post - and it started clicking. Engine OFF for this test - so you can hear of course.
To test to see if the KLR is actually actuating the valve, you can put a test lead on the valve electrical connector itself. Probe ground to one connection and the probe to the other. You can disconnect the connection to the CV itself and just connect the probe to the connector itself. A standard 12v test light works well here, or even better if you have one of those fancy shmancy LED test probes that you get from a automatic car starter install kit works better at least in my opinion - but either should work. A multimeter will NOT work as well here, as the signal happens very quickly and you might not see the result well on the meter.
Then, start the car. Two choices here, either be careful as you don't want to over-rev the car, or remove the electrical connection from one fuel injector so it can't fire.
When the car is running, if you use your hand to open up the trottle past 65 degrees, the test light should flicker.
To test to see if the KLR is actually actuating the valve, you can put a test lead on the valve electrical connector itself. Probe ground to one connection and the probe to the other. You can disconnect the connection to the CV itself and just connect the probe to the connector itself. A standard 12v test light works well here, or even better if you have one of those fancy shmancy LED test probes that you get from a automatic car starter install kit works better at least in my opinion - but either should work. A multimeter will NOT work as well here, as the signal happens very quickly and you might not see the result well on the meter.
Then, start the car. Two choices here, either be careful as you don't want to over-rev the car, or remove the electrical connection from one fuel injector so it can't fire.
When the car is running, if you use your hand to open up the trottle past 65 degrees, the test light should flicker.
05-18-2009, 02:58 PM
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I'm in Poway too. I live in Garden Road to be exact
ahh okay I'll try that tonight when I get home. I did apply 12v to the cycling valve with the car off and didn't hear any clicking, but I might have done it wrong so i'll try again.
And I tried the 12v signal to the valve from the KLR, but I had a multimeter. I saw the voltage drop like .5 volts when I gave it WOT for a second, so maybe it's working and the multimeter is just slow like you say.
Thanks!
Now I'm happy it could just be the cycling valve!
Hey - if you put 12V on the cycling valve manually (as in one connection goes to battery ground, and the other to battery positive connection) and you don't hear a 'click' then there's something wrong with the valve itself. The first time I did this on my valve, nothing happened. I tapped the ground lead onto the battery post - and it started clicking. Engine OFF for this test - so you can hear of course.
To test to see if the KLR is actually actuating the valve, you can put a test lead on the valve electrical connector itself. Probe ground to one connection and the probe to the other. You can disconnect the connection to the CV itself and just connect the probe to the connector itself. A standard 12v test light works well here, or even better if you have one of those fancy shmancy LED test probes that you get from a automatic car starter install kit works better at least in my opinion - but either should work. A multimeter will NOT work as well here, as the signal happens very quickly and you might not see the result well on the meter.
Then, start the car. Two choices here, either be careful as you don't want to over-rev the car, or remove the electrical connection from one fuel injector so it can't fire.
When the car is running, if you use your hand to open up the trottle past 65 degrees, the test light should flicker.
To test to see if the KLR is actually actuating the valve, you can put a test lead on the valve electrical connector itself. Probe ground to one connection and the probe to the other. You can disconnect the connection to the CV itself and just connect the probe to the connector itself. A standard 12v test light works well here, or even better if you have one of those fancy shmancy LED test probes that you get from a automatic car starter install kit works better at least in my opinion - but either should work. A multimeter will NOT work as well here, as the signal happens very quickly and you might not see the result well on the meter.
Then, start the car. Two choices here, either be careful as you don't want to over-rev the car, or remove the electrical connection from one fuel injector so it can't fire.
When the car is running, if you use your hand to open up the trottle past 65 degrees, the test light should flicker.
And I tried the 12v signal to the valve from the KLR, but I had a multimeter. I saw the voltage drop like .5 volts when I gave it WOT for a second, so maybe it's working and the multimeter is just slow like you say.
Thanks!
Now I'm happy it could just be the cycling valve!
05-19-2009, 03:39 AM
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Hey - if you put 12V on the cycling valve manually (as in one connection goes to battery ground, and the other to battery positive connection) and you don't hear a 'click' then there's something wrong with the valve itself. The first time I did this on my valve, nothing happened. I tapped the ground lead onto the battery post - and it started clicking. Engine OFF for this test - so you can hear of course.
Ok I tried this again tonight and no clicking at all. I tapped the ground many times on the battery post and no clicking whatsoever.
So now I need a new cycling valve, anyone got one for sale?
05-19-2009, 05:56 PM
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Small world, an ex-girlfriend of mine actually lives behind Poway High off Oakstand and I graduated from PHS in 96
Seeing it's no problem, i'll probably be working on it or one of my Sciroccos this weekend--just like every other weekend lol
If you bring by a cycling valve I'll really appreciate it
Seeing it's no problem, i'll probably be working on it or one of my Sciroccos this weekend--just like every other weekend lol
If you bring by a cycling valve I'll really appreciate it
