1999 Oldsmobile Aurora Stalls after changing the Engine Thr

LARRYTHEPLUMBER

MEMBER
1999 OLDSMOBILE AURORA
V8
2WD
AUTOMATIC
87,000 MILES

During a recent trip to the garage for a tune-up the mechanic changed the TPS (non GM replacement part). Now the "service engine soon" light comes on and the engine stalls as I come to a stop. Not every stop, but it does stall. Have taken it back to the original mechanic who says he can find nothing wrong. Took it to a GM dealer who checked it - cleared the error message - - ran disgnostics & found nothing wrong -- took it for a drive and it did not stall. WHAT CAN BE DONE TO FIX THIS PROBLEM?
Thanks, in advance, for your help.

4 Replies

FREEMBA

MECHANIC
1,152 POSTS

It would be interesting to know which code is present when the check engine light is on. The next time the light comes on, take your car to autozone or advance auto and have them to scan the computer. Write down the codes and post them here. The codes will give me a good place to start diagnosing the problem.
Meanwhile, check for obvious problems such as, make sure that the temperature sensor is plugged in (it's screwed into the intake manifold near the throttle body and should have a two wire connector plugged into it), vacuum leaks, disconnected wires etc.
Don't forget to post the codes from your car's computer.

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Wednesday, June 2nd, 2010 AT 12:30 AM

LARRYTHEPLUMBER

MEMBER
3 POSTS

Thanks for your response. Since posting my question I have taken the car to local GM dealer who scanned with computer (didn't get the code info from him) and said ALL codes were correct and all votrage readings were also correct. They took it for a drive but it did not stall for them. "Service engine" light is no longer on. Left dealership and car stalled one mile from dealership. Each time car is cranked engine revs to approx. 2100 rpm, then slowly idles back down to 600 rpm. IF light comes on again I will take it by AutoZone and get those codes for you.

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Thursday, June 3rd, 2010 AT 5:04 PM

FREEMBA

MECHANIC
1,152 POSTS

Hey Larry,

Have you cleaned the Idle Air Control Solenoid (IAC)? It located on the left side of the throttle body just above the TPS. It has a three wire connector and is held in place by two torx screws. Once you remove it, use carb cleaner and a small non-metal brush to clean it. Clean the IAC bore as well, using the brush and carb cleaner.
Sometimes they get dirty and can't close properly at idle (especially after a fast decline in engine speed--when coming to a light). This allows too much air into the engine which dilutes the air/fuel mixture and could cause the engine to stall. Doesn't always set a code.

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Friday, June 4th, 2010 AT 4:18 PM

LARRYTHEPLUMBER

MEMBER
3 POSTS

Hey Freemba, sorry to take so long to get back to you, but things have been crazy around here. Mechanic said he changed the IAC when he changed out the TPS. Both the GM dealer and local mechanic said the computer code reads: P0121 ---- but all voltage readings verify as being correct. Engine runs smoothly while driving. Problems are (1) as I come to a stop, it stalls (2) While in park it will surge numerous times then stall
(3) While stopped at a traffic light it will stumble and then stall. Thinking maybe the new TPS was faulty it was replaced today. All three problems still exist.

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Monday, June 14th, 2010 AT 9:03 PM