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1994 Skylark Custom SVC ENG LGT - 55 up


slwolbert
05-06-2007, 08:13 AM
1994 Buick Skylark Custom
3100 SFI
4 speed OD
222,000 miles

Problem:
Service Engine Light comes on at 55 MPH and over in 3 to 4 minutes of highway driving

Further explanation:
1) Vehicle runs fine before and after light comes on;

2) Light goes off when car sits for a couple minutes after shutdown; codes do not reset

3) Light does not come on at speeds below 55 MPH

4) Codes suggest EGR Solenoids bad (75, 76, 77) All three. I've replaced with same error codes popping up when driving highway speed. Initially when car was purchased codes pulled suggested EGR Solenoids, TPS, and do not remember whether it was the IAT sensor or the valve...At any rate, when erasing codes, these two did not register.

5) Also when car was purchased, found dog food in the air cleaner housing??? :screwy: I'm clueless on the reason.

Any ideas for this problem are greatly appreciated. I'm worried E-Check will stop me in my tracks if I were to take it in. :banghead:

TIA!

-Steve

maxwedge
05-06-2007, 08:37 AM
Welcome to AF. I'd be looking for blocked egr passages here, if the egr is known to be operating.

slwolbert
05-06-2007, 12:42 PM
Thanks for the info and welcome!

-Steve

slwolbert
05-06-2007, 12:52 PM
Update:

While checking voltages to the EGR, I bumped a bunched bundle of wires to the EGR, IAC, and TPS. Had the car running at the time and the RPMs went up. Discovered that one connector at the TPS was loose, in fact, it was not put in correctly to make good contact. Anyhow, fixed the problem and thus far the SVC ENG SOON light has not come on at highway speeds. Am still skeptical because I do not understand how this could solve the problem... but have some educated guesses... as in possibly the TPS and EGR are on the same registered port in the ECM/PCM?

I'll update in a week, or sooner as to if the Service Engine Soon light comes back on.

Thanks!

-Steve :popcorn:

maxwedge
05-06-2007, 03:00 PM
The pcm need the tps input to determine, as well as other sensors, whether the egr is working, wait and see. Post back the results either way.

slwolbert
05-08-2007, 01:51 PM
UPDATE:

No problems with SVC ENG Light, thus far. It passed E-check but found that the NO reading(in exhaust) was high, like 905 with a limit set at 910 for e-check. NOT THAT I AM COMPLAINING BBUUT, I try to peer into the future for further problems that may be on the rise and wonder if anyone has info as to what a high NO reading in the exhaust means or may mean in the future.

Perhaps this would be better suited in a thread by itself? At any rate, I will nose around the internet for dribblings on my posed question.

Will update if anything changes in the next couple of weeks.

Thanks for the all the info!

-Steve :)

slwolbert
06-05-2007, 01:47 PM
Update on this problem.

Seems coming off the expressway when I hit the brake to slow down the light comes on. I've also been able to pop the SVC eng light after WOT; entering highway or passing. I'm thinking the pintle in the iac may be going bad ... I'll need to check, but think this controls the opening and closing of the throttle.

Thanks

Steve

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