JohnK944T

My car fires right up and idles at 700 to 1100 rpm. BUT if I step on the gas the power just cuts out, bwwoooooow.

I have read as much as I can off the board, but still am unsure. Overall, it all started with uneven boost at 3000 rpms, then power loss at speed if I did not get into the throttle just right. Now I don't even move the car for fear a break down.

I have replaced the plugs, #4 was oily, but I think that is due to a seal for the cam cover. Oil was at the top of the threads, not the tip. I also have oil coming out somewhere around my turbo inlet, I have a pictue if someone can help me post it. Here is what I am checking;
DME RELAY ON THE WAY
BOV GOOD, SUCKED ON IT AND GOT RESISTENCE!!
BAD PLUG GOOD, ARE NEW
CAP ON THE WAY
ROTOR ON THE WAY
COIL
THROTTLE POSITION SWITCH MAKES A NICE CLICK WHEN BUTTERFLY CRACKS OPEN
FUEL PUMP ??
FUEL REGULATOR ??
SLIPPED TOOTH ON TIMING BELT ?
WEAK HOSE
CUT HOSE CAN’T SEE ANYTHING, MAYBE UNDER THE INTAKE?


ANY SUGGESTIONS? SOME I DON'T KNOW HOW TO CHECK.

THE CAR HAS HUNTLY MAF, K27DR, ARCII, ARM, ADJ. FPR. ALL WAS IN PLACE AND RUNNING GREAT PREVIOUSLY.

-JK

special tool

If your idle goes from 7 - 11, I would check error codes first.

Rob

[quote] THROTTLE POSITION SWITCH MAKES A NICE CLICK WHEN BUTTERFLY CRACKS OPEN
<hr></blockquote>

You can eliminate this item by simply unplugging it and seeing if the problem goes away. With the TPS unplugged the idle will vary quite a bit (~800-1300 rpm's), but it will be drivable.

Rob

TT

[Edit]

My bad, didn't look down at the part were you have the MAF.

The symptoms sound similar to a bad VAF or bad VAF connection. This results in the engine idling OK, but bogging down from lack of fuel as soon as you gun it. Check the voltage output of the air flow signal from the MAF to the ARCII and the ARCII to the DME. You should see a voltage that changes according to air flow. If it stays pretty much constant when you open the throttle either the MAF is bad (or not powered) or the ARCII is incorrectly adjusted (or not powered).

JohnK944T

Good Stuff! I am a rookie so I am not sure what is ment by the "VAF". Does it have something to do with vacume advance?? Also, the ARCII just sits in the glove box, and I drove the car for about a year before I discovered that it was not attached and could slide around. I wonder if there is a loose connection or bad curcuit inside. Thanks for your help I will be working on it this weekend..

-jk

Ken

It sounds EXACTLY like what mine was doing at one point. It turned out to be the throttle position sensor. It would cut out at around 1200 when i got on the gas. After I disconnected the TPS it would rev higher, but leaned out. I would definately start there!

JohnK944T

I am almost positive it is the throttle position sensor. I disconnected it and the engine revs' much smoother. I think it has failed in the closed position. Step on the throttle and the car gets air, but no fuel. Plus the connector has some oil in it from the turbo. I am sure the shop would have taken hours to diagnose and charged me big time. Thanks for the suggestions!!

-jk

special tool

If you disconnected your tps and it runs better, that is not your problem. You are getting more revs because you are now in a fault mode induced by the klr. In my opinion, you have an air problem - boost leak between turbo and throttle body, vacuum restriction before turbo, restriction at exhaust/turbine or total wastegate failure.

Rob

[quote] If you disconnected your tps and it runs better, that is not your problem <hr></blockquote>

I have to disagree. The TPS most likely is the problem. The closed throttle contacts inside the TPS are not opening when the throttle blade opens. These shorted contacts signal the DME to only provide enough fuel for idle conditions only (typically the DME provides enough fuel for about 1300 to 1500 rpms before the motor leans out enough to stall). unplugging the TPS opens these contacts thus producing a wandering idle, but eliminating the bogging.

Rob

JohnK944T

I should be able to check the current across the TPS and verify that it is working, right?? This is on my list for Sunday..

-jk

Rob

[quote]Originally posted by JohnK944T:
<strong>I should be able to check the current across the TPS and verify that it is working, right?? </strong><hr></blockquote>

Yes, here is the page from the DME/KLR test plan in case you don't have it.

Rob

special tool

Rob - he has said that he has audible click when he operates the throttle (there is actually a fault code for a correctly operating tps, but having a partially disconnected harness). The way to check for any fault code is through the test port - it takes 30 seconds and you can do it with a multimeter, led test light etc. This will eliminate any possible sensor error and he can start looking for his air problem.

JohnK944T

Great info!!, I also looked up the fault codes, so when I get time tomorrow I should know pretty quick whats going on..

Thanks, again

jk

Rob

special tool,

I do agree that doing a fault code test is a good idea and that you might be correct about it being an air leak especially since I missed the part about the auditable click, but there is no error code for the closed idle contacts of the TPS. This is because the computer can't tell the difference between the correct condition when the throttle blade is closed and a set of shorted out contacts. The fault codes are for a missing TPS sensor connection and a faulty potentiometer inside the TPS.

If it is an air leak, the problem shouldn't completely go away by disconnecting the TPS connector because the computer would have to start providing enough fuel for all the non-metered air.

The other thing to note here is that an audible click doesn't allways tell you if the tps is good (Mine would still click when it was completely junk).

Rob

Water944t

[quote]If you disconnected your tps and it runs better, that is not your problem. You are getting more revs because you are now in a fault mode induced by the klr. <hr></blockquote>

Huh?


specialtool, please stop before you get this guy as confused as you are.


It IS (with 90% certainty) the TPS. He may also have a air leak, but it is not the culprit in this case. At least not with the symptoms he is describing.

The DME/KLR doesnt go into a fault mode, it goes into a default mode when the TPS is unplugged. It enriches the fuel, and limits the boost to 1.2 bar. The DME/KLR goes into this default mode to insure that you dont grenade the engine if the TPS fails. It increases the fuel, because fuel-rich is safer than fuel-lean, and it retards the boost as well, since it can no longer accurately judge the throttle position. There is a big difference between fault and default.

It can still click all it wants, the click is a mechanical part which is NOT a indicator of a working TPS, but merely a method of setting the adjustment points. Many TPS's will click and still be fried. The potentiometer inside is what matters, not the click noise.

I have had this exact problem, and it was solved in the same manner. I was able to drive the car for several weeks with the TPS disconnected, it just meant a fuel-rich condition and less boost. At worst he might get a lower MPG, and maybe a bit of black smoke from being fuel-rich.

I know you mean well, but you are giving this guy bad info, probably from thinking of it as a fault, and not de-fault.

No hard feelings?

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />