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I see... i have my race car in , "no cat" mod, so thats why i didnt see any hunting with it.
Yep, if your race car is set up that way, it'll run open-loop all the time, and the LH's idle adaptation routine will set the idle speed by computer, so it'll be steady.
One warning - if your race car has a non-cat coding plug in it, then the devek stroker's ECU may test okay in it even if its not working in the problem car, if its just the O2 loop part of the hybrid tile which is failed in the suspect ECU. i.e. your car won't care if the emissions control part of the ECU is dead as its set to ignore those inputs to the fuelling calculations. You might need to test the suspect ECU in a more stock S4 to get a definitive "brain is ok" outcome.
Originally Posted by mark kibort
im betting on the ECU being bad, but it sounds like it could be the MAF too.
the main reason i say this... is that the tach was not working when we were trying to get it to start.
Thanks !!!
It does sound likely that the LH is the cause of the problem - they don't just fail completely in my experience, and before they get to the terminal state of injectors clikcing all the time with the ignition in position I, there can be a range of more subtle issues with mixture/O2 loop etc.
A failed MAF can also give similar symptoms however to some of the ones you describe, except it shouldn't kill the tacho needle. Of course, the tacho needle may be a different issue contributing to no-start. Before you start swapping expensive bits, just a quick basic question - do you have spark on both distributor banks? (e.g. check for spark on both cylinders 1 and 5) Testing for spark is to make sure the EZK is functioning (i.e. its getting power via the relay, and signal from the crank sensor, and isn't faulty).
Hopefully careful diagnosis and changing 1 thing at a time can narrow down exactly what the problem(s) are here - and the owner won't be traumatised by a car which may or may not have an intermittent no-start!
Yep, if your race car is set up that way, it'll run open-loop all the time, and the LH's idle adaptation routine will set the idle speed by computer, so it'll be steady.
One warning - if your race car has a non-cat coding plug in it, then the devek stroker's ECU may test okay in it even if its not working in the problem car, if its just the O2 loop part of the hybrid tile which is failed in the suspect ECU. i.e. your car won't care if the emissions control part of the ECU is dead as its set to ignore those inputs to the fuelling calculations. You might need to test the suspect ECU in a more stock S4 to get a definitive "brain is ok" outcome.
It does sound likely that the LH is the cause of the problem - they don't just fail completely in my experience, and before they get to the terminal state of injectors clikcing all the time with the ignition in position I, there can be a range of more subtle issues with mixture/O2 loop etc.
A failed MAF can also give similar symptoms however to some of the ones you describe, except it shouldn't kill the tacho needle. Of course, the tacho needle may be a different issue contributing to no-start. Before you start swapping expensive bits, just a quick basic question - do you have spark on both distributor banks? (e.g. check for spark on both cylinders 1 and 5) Testing for spark is to make sure the EZK is functioning (i.e. its getting power via the relay, and signal from the crank sensor, and isn't faulty).
Hopefully careful diagnosis and changing 1 thing at a time can narrow down exactly what the problem(s) are here - and the owner won't be traumatised by a car which may or may not have an intermittent no-start!
Thanks Hilton!!
Yes, even though the car is set in "no cat " mode, it still runs closed loop until it sees WOT .
interesting about the test of the stock ECU in my car... as a note, I do have it coded for the "no cat " config.
Yes, we have spark on both sides of the distrib.
we will start with the fuel flow, and an attempt to start with no maf attached.
Im still thinking ECU because of that tach thing. also, its likely when he was messing with the wiring, he pulled the ECU with the power applied and maybe when he reconnected, it blew with a arc from the battery.
If you listened to -anyones- advice on -anything-, you'd be in a better place with this.
I'm not the troll.
You keep doing it, well, wrong. You just keep coming back. And it's not for a lack of people asking to help either.
Who else has done what you're doing with similar, success?
This is precisely why a lot of people refuse to give Mark any advice at all. Just look at this thread, he never really wants advice but a reaffirmation of his own opinions. He's been told to replace the FPR a dozen times but refuses to think that could be the problem because he "knows" its fine because he doesn't smell any fuel in the vacuum line. What he might just realize that there are several failure points to one and he's looking at only one of them.
This is precisely why a lot of people refuse to give Mark any advice at all. Just look at this thread, he never really wants advice but a reaffirmation of his own opinions. He's been told to replace the FPR a dozen times but refuses to think that could be the problem because he "knows" its fine because he doesn't smell any fuel in the vacuum line. What he might just realize that there are several failure points to one and he's looking at only one of them.
Ill say this again..cuz I have the past.
I have a supermaf, and working ECUs with PEMs sittin here to help...and there SHOULD be a close-enough working map to start, and the skys the limit from there.
This is precisely why a lot of people refuse to give Mark any advice at all. Just look at this thread, he never really wants advice but a reaffirmation of his own opinions. He's been told to replace the FPR a dozen times but refuses to think that could be the problem because he "knows" its fine because he doesn't smell any fuel in the vacuum line. What he might just realize that there are several failure points to one and he's looking at only one of them.
Sean, this couldn't be further than the truth. im not an expert in this stuff, and i have solved many problems by use of help FROM this list. but things got to make sense. you have to use logic.. Im going to make you think before you propose something....if im wrong about it, lets talk, but com'on..... if a damper is bad and leaking and we remove the vacuum line... its a non issue. it cant be dumping fuel in the intake... .. the FPR is keeping pressure in the line.. doing what its supposed to do, how , can that be a problem? I dont "know" its fine, but its seems to be doing exactly what its supposed to be doing. And , you say i only have "not smelled fuel in the vacuum line" , and thats not a true statement either. I tested fuel present out the vacuum line, AND tested the pressure of the RRFR. so, you tell me how else that device could not be workign and why swap it out, even though a dozen recommendations to do so. why Sean!! ???
we have jumpered the relays... they all work. we have spark.
the real variables, and correct me if im wrong, is the fuel pump, even though it shows static pressure being good. the ECU and the MAF. im not a big fan of just changing out things. folks have driven me that way before and its usually always the the things that are most logical. Now, if the MAF and ECU have interaction, dont you think i should check those things first. again, the RRFR doesnt seem to be an issue, so why start there. its not leaking, vacuum lline removed and is holding the spec pressure.
Originally Posted by Speedtoys
Ill say this again..cuz I have the past.
I have a supermaf, and working ECUs with PEMs sittin here to help...and there SHOULD be a close-enough working map to start, and the skys the limit from there.
I think the owner would love to see if those two most likely culprits are the source of the issue. thanks.... are you near by sunnyvale?
the only real question i have about the things we tested is why the fuel pressure is zero and the car was running, aleit horribly. (like 4 cylinders). some say , it could be the injectors being turned full-on, due to an ECU glitch. or the pump is clogged. waiting for the flow analysis from the owner of the pump. also the MAF disconnect test and then the resistance measurement of the TEMP II.
still thinking ECU because there is no tach working , so its not getting a signal.
fuel pump was strong. flow was near 1/2 gallon into a bucket in 30seconds.
edit:
another tidbit of information ..... a bunch of gas was leaking out the exhaust at the CAT. LOTS OF GAS folks. how did it get there? you got it.. injectors.
Sean.... all the vacuum lines are disonnected so it couldn't go in the intake.
so, it sure points to ECU forcing all injectors on 100% and that also coincides with the lack of fuel pressure, if all injectors are stuck wide open.
he was messing with the wiring board. he unplugged the ECU and probably zapped it as it is unfused when he reconnecting.
do you see a problem with that logic?
Last edited by mark kibort; 04-07-2015 at 05:27 PM.
since the validity of the answers is based entirely on the info provided,
the more accurate and verbose the info is the more accurate the answers will be.
That said from the info provided make sure to plug the dampers and FPR if you decide to not keep the vacuum lines connected to them .
Reason being if they should decide to leak then you will have raw fuel running out of them and spilling on the engine, possibly while its running ,
and leaky spark plug wires will always ignite spilled fuel.
Moving on, if you see indications of the computer failure then you should have your set tested in another car first.
Unless you have a catastrophic computer failure.
NOTE dont be in a haste to swap in another set into your non running car ,
as more info needs to be gotten about what wires have been messed with,
this so you dont possibly fry another set of the computers.
NOTE when you do swap in another set of computers,
follow Jim Cs advice about coding plug configuration.
Have a spare MAF thats a known to be good part handy to swap in .
I dont have a running car to test your ECUs with Mark, but I work in Sunnyvale, and Im free on weekends generally outside of NASA events.
I would love to stick a stock ECU in his car to see, or maybe just the maf if you don want to take the chance with the ecu swap. thanks... we are available, most anytime... after work on the way home if you drive hy9? oh, wiring board.... ha ha... i meant fuse panel
Originally Posted by Mrmerlin
since the validity of the answers is based entirely on the info provided,
the more accurate and verbose the info is the more accurate the answers will be.
That said from the info provided make sure to plug the dampers and FPR if you decide to not keep the vacuum lines connected to them .
Reason being if they should decide to leak then you will have raw fuel running out of them and spilling on the engine, possibly while its running ,
and leaky spark plug wires will always ignite spilled fuel.
Moving on, if you see indications of the computer failure then you should have your set tested in another car first.
Unless you have a catastrophic computer failure.
NOTE dont be in a haste to swap in another set into your non running car ,
as more info needs to be gotten about what wires have been messed with,
this so you dont possibly fry another set of the computers.
NOTE when you do swap in another set of computers,
follow Jim Cs advice about coding plug configuration.
Have a spare MAF thats a known to be good part handy to swap in .
I agree with the swap.. got to be careful to find the root cause of the issue.
the coding plug is set for US manual... nothing special...even though he isnt running a cat, but still running an o2 sensor.
the one front fuel damper is slightly leaking.. with it disconnected from the vacuum, it barely puts out any fuel.... a few drops under pressure. thats why i dont think its the issue. if it failed catastrophically, it would be a fuel mess... tough to clamp off 50psi on that nipple. i dont think its a big deal, but certainly could be responsible for the hard hot starts
i dont seem to follow you on the ECU swap. we dont think any wires were messed with. only a few positive wires for the lighting.. ... i seem to believe that the ecu fried when it was plugged in and out with battery attached, and battery tender attached. are you saying we should put a good known ECU in to his not running car and see? maybe we can start with Jeffs MAF and do a quick test... i still think ecu... especially with the lack of Tach signal.
you have to use logic..
.....
I tested fuel present out the vacuum line, AND tested the pressure of the RRFR. so, you tell me how else that device could not be workign
1. When you pulled vacuum on the vacuum port of the damper to test it, some fuel came out.
2. When the engine is turning, and that dampener port is connected, the engine pulls vacuum on the port, so fuel comes out.
Whilst its not the sole cause of the problem with the large amount of fuel in the intake, the dampener does need to be replaced because it has failed. Also, a small leak now will get worse, as the crack in the old/worn diaphragm lengthens. When it gets bad enough to push more than a dribble of fuel, you'll have 45psi of fuel pressure pushing unclamped rubber elbows off plastic lines and spraying fuel around the engine bay.. for about 1s before it bursts into flames and starts to burn harnesses and rubber fuel lines.
Originally Posted by mark kibort
it sure points to ECU forcing all injectors on 100% and that also coincides with the lack of fuel pressure, if all injectors are stuck wide open.
he was messing with the wiring board. he unplugged the ECU and probably zapped it as it is unfused when he reconnecting.
do you see a problem with that logic?
The ECU does sound suspect - but your story about zapping the ECU is based on assumption/conjecture. The ECU may not even be the issue until you've proven it is the problem by eliminating other possible causes.
You should also be testing the injector harness to make sure that the owner hasn't caused the harness to ground somewhere after the ECU. Unplug the LH harness and measure the injector pin (18) to ground (17) for continuity while isolated from the ECU. They should not be connected.
While you're testing pins, also test:
the idle and WOT switches (pins 2 and 3) to ground and make sure it switches when the accellerator pedal is pushed/released (failed idle switch can cause no-start, so just covering bases while you're measuring the harness in case you've got more than one issue).
the Temp II pin (pin 13) to ground (17) to make sure there isn't a fault in the harness from the temp II sender (as it affects cold-start enrichment and can cause no-start)
I would love to stick a stock ECU in his car to see, or maybe just the maf if you don want to take the chance with the ecu swap. thanks... we are available, most anytime... after work on the way home if you drive hy9? oh, wiring board.... ha ha... i meant fuse panel
Given the possible wiring issues, I wouldn't put yours or anyone else's ecu in the problem car until the LH harness been verified to not be carrying voltage on any pins that shouldn't have it, and there are no shorts where there shouldn't be. Putting the suspect ECU into a stock S4 is more helpful and less risky, but Jeff doesn't have a running S4 currently (after his engine ate metal supercharger bits) to test brains in.
Your racer's ECU is stock Mark - the non-cat coding is via a separate coding plug on the harness which doesn't change the ECU itself. All S4 LH ecu's are interchangeable regardless of whether the car is auto/manual/cat/non-cat etc.
edit: Found this old post by Rich Andrade. You can skip a and b as you have spark (and failed hall sensor doesn't cause no-start):
Originally Posted by Rich9928p
I am seeing many more failing LH Jetronic fuel injection modules this season. I've given a lot of diagnostic advice one-off and thought I'd share it with the group.
Many people jump to the most expensive part when a no-start or bad running problems occur. That isn't the way to go. If you or your mechanic have eliminated the "easy to find things" ... this list of diagnosis goes a lot deeper.
All functionality with the EZK spark system must be confirmed prior to testing the LH Jetronic system.
Sometimes the diagnosis can be more expensive then the repair! So feel free to share this information with your shop, it could save you money.
===========
928 Model year 1987 – 1988 System No Start Diagnostics (later model diagnosis is similar, consult the wiring diagrams for specifics):
Diagnostics should be only be performed by a trained technician. Always check for proper relay functionality and power/ground connections before undertaking further diagnostic testing.
a. Testing the engine RPM sensor. The EZK spark control is the system master, if engine rotation signals are not provided to the EZK, spark will not be generated and EZK will not provide a turn-on signal to the LH Jetronic fuel injection system. The RPM sensor input to the EZK is from an inductive RPM sensor. Inductive RPM sensors generate voltage so a VOM can be used for testing the sensor. EZK pins 23 and 6 are connected to the RPM sensor; pin 6 is ground and is connected to master-ground pin 18. EZK pin 24 is the shielding of the sensor cable and is connected internally to pin 18.
b. The Hall Effect engine position sensor can be tested with an LED tester. The EZK provides the power supply for the Hall Sensor at pin number 5 (12V). The EZK provides a 5V level at pin number 22, which the Hall sensor can pull down to ground. Pin EZK pin 22 is the "hot" signal cable and therefore is shielded. The cable shielding is connected to EZK pin 4, and pin 4 is connected internally to master-ground EZK pin 18.
c. The EZK spark module provides the signal to turn on the LH fuel injection module; it is the circuit from EZK pin 13 to LH control Pin 1. Check for continuity, if the wire is broken or the connection isn't clean, the car will not start.
d. The circuit from LH Pin 20 goes to the Fuel Pump Relay XX pin 85, check for continuity between these two points.
e. From the Fuel Pump Relay XX pin 87 the circuit passes through fuse 42 then to the fuel pump motor. Pull the fuse, check the fuse, and clean the connectors. Check the continuity of this path. Bridge Fuel Pump Relay XX socket points 30 and 87, the fuel pump should run.
f. There should be 12V (nominal battery voltage) at the fuel pump and LH relay pins 30 at all times. This same circuit connects to LH connector Pin 4, check for 12V there too.
g. The LH relay XXV pin 85 connects to LH connector pin 21, check for continuity between these two points.
h. The LH connector pin 18 connects to all the fuel injectors. The LH functions as the switch from the fuel injector to ground. With the LH relay jumpered between pins 30 and 87, there should be 12 V at pin 18. [Model Year 1989 and newer 928s have a spark monitoring system, consult the wiring schematics and workshop manuals.]
i. Power and Ground connections are key points to inspect and clean. The LH is grounded via Pin 17 to chassis ground point VIII. Use an Ohm meter to measure the resistance between LH connector Pin 17 and a chassis ground point. It should read as close to zero as possible. If it reads a high resistance, a corroded ground connection at MP VII or cut in the wire could be the problem.
j. If all of these items check out OK, and the fuel pump is functioning, then potential problems could be:
- The system fuel pressure is too low; fuel filter or pipes are restricted, fuel injectors are not functioning correctly
- The LH Jetronic fuel injection module is not functioning correctly and requires a rebuild.
Common symptoms of a failing LH injection module
- Fuel injection valves click when the ignition turned is on and engine is not running
- Air-fuel mixture is too rich (this can damage catalytic converters)
- Engine will not run at idle
- No fuel pump operation, but the fuel pump operates when its relay is jumpered
- The engine will not rev higher than 3000 RPM
- A/T cars: no idle speed regulation when switching between drive gears and neutral or park
- Engine will not start, spark plugs are dry and the ignition system produces spark.
>> warning, if you replace a failed LH module with a used one, you may have a failure in the near future. The failure symptoms seem to be "module age" related, not number of operating hour related. I've spokent to people who've purchased used units and they've failed within six months. Insist on a replacement that has had the hybrid chip removed and exchanged.
1. When you pulled vacuum on the vacuum port of the damper to test it, some fuel came out.
2. When the engine is turning, and that dampener port is connected, the engine pulls vacuum on the port.
Whilst its not the sole cause of the problem with the large amount of fuel in the intake, the dampener does need to be replaced because it has failed. Also, a small leak now will get worse, as the crack in the old/worn diaphragm lengthens.
The ECU does sound suspect - but your story about zapping the ECU is based on assumption/conjecture. The ECU may not even be the issue until you've proven it is the problem by eliminating other possible causes.
You should also be testing the injector harness to make sure that the owner hasn't caused the harness to ground somewhere after the ECU. Unplug the LH harness and measure the injector pin (18) to ground (17) for continuity while isolated from the ECU. They should not be connected.
While you're testing pins, also test:
the idle and WOT switches (pins 2 and 3) to ground and make sure it switches when the accellerator pedal is pushed/released (failed idle switch can cause no-start, so just covering bases while you're measuring the harness in case you've got more than one issue).
the Temp II pin (pin 13) to ground (17) to make sure there isn't a fault in the harness from the temp II sender (as it affects cold-start enrichment and can cause no-start)
thanks!
Yes, the vacuum applied to the damper, pulls a tiny bit of gas.. sure, it will be replaced.
thanks for the ideas on seeing if there is a false ground.. good idea. and yes, my assumption that the disconnect was the cause is complete conjecture. i dont know what is wrong, but we have rulled out the fuel reg, dampers and fuel pump. there are some small issues with them,, but they are not the cause of the major issue . (i.e. fuel pump check valve, leaky damper, and/ or leaky injector)
do you remeber the ohm reading from each of the temp II pins to ground in the engine bay?
so, i should take his ecu and see if it starts my car?
do you remeber the ohm reading from each of the temp II pins to ground in the engine bay?
so, i should take his ecu and see if it starts my car?
I just looked it up - see pic below. You can find the "LH Diagnosis/Troubleshooting" booklet in the back of Volume 1A of the WSM on the Moorehouse CD set.
Yes, testing his ecu in your car is a good idea.
Also I edited my post above after you read it, to add an excellent old post from Rich Andrade on points to test for LH failure.
Thanks Hilton... I wasn't near my manauals these past few days and have been communicating with the owner via text and phone aside from my one courtesy visit
Ill do some testing tomorrow , but that ECU is cooked I would bet. might have a chance to try it in my car this weekend.
04-07-2015, 02:04 AM
