Engine hesitating while driving

[forgerat1]

OK. I've read a few that are close to my problem, but I will explain my problem. I have a 2005 GT 3.8L Nat. Asp. The engine will hesitate(chug) while I am driving. This is an intermittant problem. It may only happen once a week, once a month, there is no rhyme nor reason for when it acts up. It will do the chugging at low speed, feels like I have a boat anchor attached. It also seems to shift hard when this is happening. When I get up to highway speeds, I will be running along well and all the sudden it will start hesitating, I will lose RPMs and speed. So I push the gas to get back up to speed, then it may or may not start to gain speed and R's like it is coming out of the problem. I have had the dealer repair this under warranty multiple times. They have replaced the MAF twice and reprogrammed the PCM three times. The last time they changed the MAF they said it was bad from the K&N filter I had on it. I don't believe it was the MAF either time because it will do it again after the MAF is replaced. I have shut it off while this is happening(put it in neutral and coast, shut it off for a 10-15 seconds and restart) and it seems to clear it up. Any help would be greatly appreciated.

[Liquifire]

plugs? wires? bad gas/ fuel filter? fuel pressure regulator? coil packs? Does it ever throw any codes or messages? does it only do it while you are driving or in park also? Does it have any issues starting? Need info.............

[flash527]

i would start with plugs, then the cat honestly; check for any blockages.

[forgerat1]

No codes. Don't think its bad gas. On the same tank of gas it will act up one time of driving and not the next. I've only got 50,000 miles. It only does it while driving. It is very intermittant. No starting issues. Its done this same thing before it got to 15,000 miles.

[Liquifire]

No codes. Don't think its bad gas. On the same tank of gas it will act up one time of driving and not the next. I've only got 50,000 miles. It only does it while driving. It is very intermittant. No starting issues. Its done this same thing before it got to 15,000 miles.

if you have had this problem this long, why didnt you take it in under warranty? Have you had it in at all and analyzed? does this happen when engine is cold or warm or both? driving at what speeds? certain rpm ranges only?

[forgerat1]

It has been under warranty. MAF changed twice. PCM reprogrammed 3 times. I assume they analyzed it. How would they know to change the MAf if they didnt? Doesn't matter speed, rpm, hot or cold?

[Liquifire]

My only guesses at this point are the plugs, wires, coils,or the cat............I mean this is a shot in the dark........if the stealership cant figure it out with their tools, it will be hard to get this figured out. Sorry I cant be of more help.....

[flash527]

my money is still on plugs or cat. replace the plugs (cheap test). and check the cat and the rest of the exhaust for any blockages.

[forgerat1]

It happened again. I got to the dealer and had them put the analyzer on it and do a road test before I shut it off. They found one code in the pcm and it was for a sensor in the transmission. They said it could be one of three sensors in the tranny. Apparently what it is doing is hunting for what gear it should be in. This must be why when it was at idle or just by reving it up it showed no signs of anything wrong. Thanks for all your suggestions and help.

[flash527]

if its just a sensor, hopefully its cheap? glad you figured it out!

[steele286]

It happened again. I got to the dealer and had them put the analyzer on it and do a road test before I shut it off. They found one code in the pcm and it was for a sensor in the transmission. They said it could be one of three sensors in the tranny. Apparently what it is doing is hunting for what gear it should be in. This must be why when it was at idle or just by reving it up it showed no signs of anything wrong. Thanks for all your suggestions and help.

Hello........

About your Reply to your Problem with your Grand Prix, I have the same issue, along with others and was wondering what Sensor or what the dealership finally do to fix the problem?


Appreciate your response!

Thanks,

Steve!

[forgerat1]

Steve,

I have not fixed the problem. When I notice it happening, I shut the car off for about ten seconds and then turn it back on and the problem usually goes away. I should probably get it fixed since I don't know what damage it doing to the tranny. For the dealer to find the problem it needs to be happening when they put their scanner on it and it never seems to happen when I could get it to the dealer or their closed when it happens.

The dealer doesn't seem to be much help unless their scanner shows something blatantly obvious. You would think with computers these days they would have some kind of database between all dealers to see if there have been any other problems of this sort and what the fix was.

Sorry I couldn't help.