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2000 Pontiac Gr Prix Rough Idle/Dies while driving


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tam
New User

Apr 26, 2010, 11:01 AM

Post #1 of 5 (8671 views)
2000 Pontiac Gr Prix Rough Idle/Dies while driving Sign In

The 2000 Pontiac Grand Prix GT 3.8L in questions has 148,000 miles. It has original plugs and wires which are all firing. Check Engine Light is on when these events occured.
1/29/10 Car died without warning while driving slow in a parking lot, no power, all dash lights on, started back up without hesitation.
1/31/10 Car died without warning while driving slow in a parking lot, no power, all dash lights on, started back up without hesitation.
2/01/10 Added HEET to gas tank.
2/03/10 Car died without warning while turning through an intersetion, no power, all dash lights on, coasted to the side of the road, started back up without hesitation.
2/03/10 Added Fuel Injector Cleaner to gas tank.
2/04/10 Idled rough at light, tach slightly up and down, coughed like it wanted to die, pressed gas pedal to keep. running, pulled into a parking lot, sat at idle for a few minutes, idled rough, then died. Started up without hesitation. Idled rough again at the next stop light, pressed gas pedal to keep running, got it home and parked it.
2/17/10 Oil change, new fuel filter, drove fine for a few days.
3/01/10 Car died without warning while traveling 40 mph, tach moved way up and down before car died, coasted to a stop, car started without hesitation.....another block and the car died again w/o warning, tried twice to start before it would start, went around the corner at the light and car died again, tried three times before it would start. Pulled into a parking lot, turned off the car and let sit for 20 minutes. Started without hesitation, got it home and parked it.
Started it once a week, but did not drive it again until 4/15/10.
4/15/10 Took car to dealer for code scan and an auto repair shop for code scan. Both indicated codes P0128 and P0102. Replaced the thermosat, PCV and cleaned the MAF.
4/17/10 Check engine light is on again. Rough idle at start, sputters after driving about 20 minutes at the light, acts like it wants to die, pressed gas pedal to keep running, got it to work. Drove it home with out incident after it sat for 8 hrs.
4/23/10 Replaced MAF sensor with a reconditioned one. Ran fine 4/23, did not drive on 4/24.
4/25/10 Check engine light back on. No problem when started cold. Rough idle for a minute or less when started warm, or evened out when gas pedal was pressed a few times. Drove to auto zone to scan for codes. Got code P0171, bank one.
The random tach up and down and the rough idle while stopped has not occured since the MAF was replaced. The car has not hesitated or died while driving since the MAF was replaced. Only issue now seems to be the idle surge and rough start when the car is warm. Welcome input. Thank you.


Sidom
Veteran / Moderator
Sidom profile image

Apr 27, 2010, 6:08 PM

Post #2 of 5 (8646 views)
Re: 2000 Pontiac Gr Prix Rough Idle/Dies while driving Sign In

Make sure all the hoses got connected correctly when the MAF was replaced.

Make sure there is no vacuum leaks....

And STOP pouring bottles of stuff into your gas tank whenever there is a problem......


tam
New User

Apr 28, 2010, 10:47 AM

Post #3 of 5 (8633 views)
Re: 2000 Pontiac Gr Prix Rough Idle/Dies while driving Sign In

Something new yesterday. Drove my car to work (about a 20 minute drive one way in stop and slow go traffic). 5 hours later went to lunch, started the car and the gas gauge jerked up and down and I could smell raw fuel. This lasted about 30 seconds, then the gauge jerked down to where it should be and the idle stabalized and the smell went away. Left the car running for about 2-3 minutes. Turned it off for about 1 minute then started it again with the same results. Did not drive the car anywhere for lunch. 3 hours later left work, started the car...the gas gauge did not jerk up and down (it quickly jumped up and then went down to its appropriate spot, which seems more normal), car did idle rough for a minute then settled down. Could faintly smell gas at one point in the trip home and the car did not run as smooth as it should and at one point I took it to 50 mph and it jerked/surged a little. Got home. Car is in the gargage at my house and I got a ride to work today. Asked a friends mechanic over the phone what to do next, he said to start with a really good Fuel Injector Cleaner. Came to work, read the response to my original post, which indicates to NOT put Fuel Injector Cleaner in the gas tank.
Something is really screwing with the Air/Fuel mix.......one thing, more than one thing???? Would a vacuum leak cause these kinds of problems? Would a clogged fuel injector cause these kinds of problems? Again, comments and/or suggestions are welcome. Thank you.


Sidom
Veteran / Moderator
Sidom profile image

Apr 28, 2010, 6:30 PM

Post #4 of 5 (8623 views)
Re: 2000 Pontiac Gr Prix Rough Idle/Dies while driving Sign In

Don't misinterpret what I said....

Running a good fuel injector cleaner every so often when you fill your tank is a good maintenance thing to do to prevent problems.

The 1st post I read, if I read it correctly said that you added a couple of different bottles of additives within a few days of each other.... Most additives are designed to be used with a full tank & by themselves....... You've already run injector cleaner thru your tank so running more now isn't going to solve any problems. I won't say that it never solves problems but the odds are low. I'm sure some people have gotten lucky or it was just coincidence when they add it and the car ran better but you've already played that card so putting in more now isn't a good idea...

It sounds like you have a few things going on and some of the original problems have been fixed and some new stuff is popping up....

You want to start out with the basics, get the battery tested to start out with. A bad battery can cause some strange problems. It sounds like you are having the problem when it's cold or sits for a long time. If it does it all the time, then that would be when you want to take some readings. Fuel pressure, if you can look at a data stream to see if any sensors are acting up and check the readings of the new MAF to make sure it's within specs... Pull codes again to see if there are any new codes.... Do a visual on the lines and injectors to make sure there isn't any external leaks.....

A vacuum leak isn't going to affect your gauge or give you problems at higher rpms, a injector could give you problems at idle & higher speeds but won't affect the gauge...

It really needs to be looked at with the right equipment when the problem is happening and I would pay close attention to what that new MAF is doing if it is an aftermarket rebuild.........

I'm sure if anyone else has any suggestions they'll let you know...........


tam
New User

Apr 29, 2010, 7:38 AM

Post #5 of 5 (8609 views)
Re: 2000 Pontiac Gr Prix Rough Idle/Dies while driving Sign In

Thanks for the update and the clarification. The battery is new, probably shouldn't put more Injector Cleaner in it, the MAF checked out ok. Not excited about starting over - again. I'm thinking a vacuum leak somewhere, a bad injector and a bad fuel pressure sensor. But.....out of time, money and patience. Will have to revisit this problem at a later date. I appreciate your responses and input.
Thank you.






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