1995 GMC Yukon ECR opens when its not supposed to please he

HOTRODTODD

MEMBER
1995 GMC YUKON
V8
4WD
AUTOMATIC
133,000 MILES

Hello all,

GMC Yukon 5.7L throttle body injection

My problem is above idle between 1000-2000 or so rpm or part throttle the engine misses and wants to stall but just recovers in time, idle and full throttle are not affected. My mechanic scanned the truck and the EGR is opening 100% with part throttle and causing the engine to run ruff, and after inspection the EGR soleniod was missing the little foam piece bellow the vacume line and thought debris might have got lodged inside and be the problem. So we replaced that and no luck, the EGR is opening fine, the TPS is working fine, plugs, cap, wires have been replaced BUT if the vacume line going to the solenoid is disconnected the problem goes away (although I didnt road test it just in neutral test anyway) the check engine light isnt on and there were no codes indicating any other problem.

I have searched everywhere online and all I have seen is the ilde bypass circut being clogged, o/2 sensors, vacume leaks, EGR and solenoid replacement. I really need this provlem fixed any help is much appreciated.

3 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Are there any codes listed? If so what numbers?

One common issue with these is a weak spring in the EGR valve. Have not had any success with after market ones, recommend an ac delco.
To test this, open egr with hand vacuum pump with the engine off. Have someone else start the engine, valve should slam closed. If it doesn't, then it's not working correct and needs replacement.

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Friday, April 18th, 2008 AT 5:30 AM

HOTRODTODD

MEMBER
3 POSTS

Probem solved,

It was the EGR itself and was the spring, I was told at the local gm dealer that they replace the solenoid and EGR in pairs so I didnt waste money on that either.

It was a ruff battle attempting to save a few bucks AGAINST the advise here by going with a aftermarket one, after having two of the wrong ones I got the AC/Delco one and worked first try and it was only $30 more.

Thanks again and now somebody else can learn from my mistakes, I will return again in the future.

Todd

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Friday, April 18th, 2008 AT 10:20 PM

SERVICE WRITER

MECHANIC
9,123 POSTS

Glad it worked out. I know all too well about wanting to save some cash and going with an available part that should work. But doesn't. IT becomes a learning experience when you hit a part that you test as bad, replace it with a new one and the problem is still present. You get caught in a dilemma of questioning you troubleshooting or the part replaced. Glad you went down the right path. Congrats! And thank-you for the donation.

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Saturday, April 19th, 2008 AT 5:35 AM