1994 Buick Lesabre Check Engine light-- Engine misses @ cru

Tiny
STALLTERS
  • MEMBER
  • 1994 BUICK LESABRE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 90,000 MILES
My 1994 Buick Lesabre shows a check engine light after warming up. The engine misses on all cylynders according to the scanner. It shows an EGR valve pintle position error. In a "data "mode, while driving the scanner shows the EGR works fine, except when I accelerate and the EGR% needed figure gets to 80% +. Then the EGR shuts down to 0% (as expected under that acceleration), but as the car gets up to speed the EGR never kicks back in. It stays at 0% EGR, no mattter what the required % is on the scanner and all cylinders miss intermitently. Unless I back off on the throttle completely for just a second, then the EGER function kicks in again and resumes properly and engine smooths out. Should I change the EGR. I have tried clening it already in case it is sticking.
Saturday, April 5th, 2008 AT 8:14 AM

4 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
If you cleaned the valve, and the port, couldn't hurt.
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Saturday, April 5th, 2008 AT 8:20 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
From: stallters
To: merlin2021
Posted: Sat Apr 05, 2008 4:20 pm
Subject: My 1994 Lesabre
Thanks for your reply, but I hate to spend the $150 on a new EGR if something else could be causing the EGR to act this way. You say it couldn't hurt.
Should I replace an EGR @ 90,000 mi as a routine maintenance anyway? I just paid $2000 for this car and hate to put a bunch of $$ in unecessary parts, trying to troubleshoot it. One mechanic told me the EGR wouldn't cause a miss at criusing speed anyway. Maybe I have 2 separate problems? What other components should I check or monitor with the OBD scanner to diagnose this problem? Or should I just shut up and spend the $$ on an EGR and whatever else might be needed after that. I just hate to be a "parts changer"
Answer to PM: No you can check it with a vacuum pump, see if it operater freely and returns to the closed posistion, Does yours have any electrical connectors? Or just vacuum? And is there a P or an N stamped on it?
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Saturday, April 5th, 2008 AT 8:07 PM
Tiny
STALLTERS
  • MEMBER
  • 3 POSTS
It has an all electric "Linear EGR" no Vacum operation to it. There is a position sensor built in to tell the PCM what is going on. Those are the readings the scanner picked up telling me the EGR was not opening, after the car got up to cruising speed, even if I slowed down and sped up again. The EGR only resumes operation after I back off the throttle completely, then it seems to reset and work again. As long as I don't come to a stop and punch it enough to accelerate and bring the pintle position sensor voltage above 3.2Volts and trip the failure again. I have messed with it enough to find a real consistency to the operation and I think it is in fact a failure. It isn't supposed to work like that, is it?
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Saturday, April 5th, 2008 AT 8:53 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
With these digital PCM control movement, so it's either the EGR or PCM! Check PCM grounds and power.
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Sunday, April 6th, 2008 AT 8:40 AM

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