Car almost stalls but bounces back repeatedly? [Archive] - GrandAmGT.com Forum

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EBlend
10-19-2006, 09:29 PM
Hello

Ever since I got my car back on the road I have noticed some strange idle problems. What happens is that after driving for either a short time or a long time, when I park my car and want to idle, the rpms go just up to 500 and car almost stalls, light dim alot, and then the car kicks in and it bumps the rpms up to 800, and then it falls again. I never had it actually stall out yet, but it will keep doing this on and off. Lights dim ALOT when this happens if it happens at night, but it happens during the day time too. At other times its perfectly normal and no problems. I don't have no stereo system right now, all is stock pretty much. New oxigen sensor has been replaced since this problem started happening and I didn't see anything for about 2 weeks, but happened again today. It is completely random at when it will happen. Would a dieing alternator cause such a problem. Iwill have it checked at a local store, but it seems so intermittent that they may not detect a fault if there is one? I wanted to ask before i spend countless hours on this. Ohh and if i give it gas when its stalling out it will keep going, but as soon as i let it go it will start the cycle again. When it first started happening i would shut the car down and start again and all is fine, but tonight it kept on doing the same thing over and over.

jaketuff
10-19-2006, 09:31 PM
Make sure that the battery is connected tightly. Make sure the PCM is fitted tightly. Check spark... It is electrical.

Prolly not an alternator, as you would have killed the battery by now.

OUT

EBlend
10-19-2006, 09:43 PM
thanks, any other suggestions welcome. I will be doing alot more work on it this weekend to try to pin down the problem, but i want ideas as to where to look.

Also I don't think its related to the car sitting for about 8 month before this all happened. After i got the kit on I put it on a long road trip (2000km) in 48 hours, and the problem first happened 300ish km into my trip when i stoped for gas. Then again at my next stop at 1000ish kms (there were other stops in between when the problem didn't happen) Then it didn't happen until i just just now, which is about 2100km since my trip. So hope its something simple, really don't want to put anymore money into it

jaketuff
10-19-2006, 09:49 PM
No more money, word.

Perhaps bad gas, but doubtful. Perhaps a bad fuel filter??? Doubtful. Sounds mostly to electric/ignition related and that is not a complex system to cross check. Check plugs, battery, tps...

OUT

lone_wolf025
10-19-2006, 09:59 PM
Check your IAC. If the problem only occurs at idle that could be the culprit. Its either that or TPS. My money's on IAC.

EBlend
10-19-2006, 10:02 PM
Yah i read in another post that it could be the IAC problem and how it was resolved with brake cleaner. I have no idea what IAC is or where its at, but got the repair manual so will look through it to figure it out

Thanks all for suggestions much appreciated. More i get more places I can look

pokesmot
10-19-2006, 10:24 PM
Hey, new to the forums here, but came here through GAOwnersClub.com

Not sure what year or make / engine your car has... but try tapping the MAF sensor with a screwdriver. If the engine faulters that is most likely the culprit.

another thing to check is the PRNDL shift indicator beside your shifter (assuming you have console shift) Are the orange LED's lit up when you shift into park / drive, etc ?

lone_wolf025
10-19-2006, 10:46 PM
Yah i read in another post that it could be the IAC problem and how it was resolved with brake cleaner. I have no idea what IAC is or where its at, but got the repair manual so will look through it to figure it out

Thanks all for suggestions much appreciated. More i get more places I can look

IAC= Idle Air Control. Basically its a motor that allows air into the engine when the throttle is closed. It should be a "sensor" right around the Throttle Position Sensor (TPS). I haven't read the thread but give it a shot.

williamGT
10-19-2006, 11:02 PM
Okay this has happend to me. So heres what GM said when they fixed it(warranty)
When driving and cornering vehicle staling,mostly noticeable around 40/60KM/H, RPM will go up to 1000 and drop to 400-erratic and will stall. Put into neutral and will refire. When slowing down the lights will dim and brighten up again (Diag for Ext warranty) Just had engine repairs completed see file.- Tech comments: Found that when load on engine and not accelerating vehicle almost stalls. performed AVR test and found when idling putting out 34 amps and when loaded up only puts 40 amps. Ordered new alternator. Replaced alternator. Checked and putting out proper amperage. Test drove and still intermittantly stalls. Checked for bulletins and found #02-08-45-002A. Applied bulletin drove again. Problem gone.-Warranty.
Hope this helps.

EBlend
10-19-2006, 11:05 PM
okie looked up that TBS online and seems like a loose ground. Do you know where this ground is? to the chasis? on the battery? on alt? Any idea?

williamGT
10-19-2006, 11:07 PM
Alternator. Thats what GM told me.

Sprucegagt
10-19-2006, 11:41 PM
I would be really surprised if an alternator was causing that problem. The lights are dimming because at 500 rpm or less the PCM will turn off the voltage regulator in the alternator. Effectively turning the alternator off, and with that, reducing your voltage from 14 to 12 or less volts. I think either the IAC is going bad or the MAF.