Pontiac Grand Am V6 Rough Idle and Hesitation

Hi everyone… I own a 2004 Pontiac Grand Am V6… recently it has developed a rough idle - kind of like the car is hiccuping - and it hesitates when I accelerate from a stop. Now, it doesn’t have issues changing gears so I’m not inclined to believe its a transmission issue…thought it might be the fuel filter, but I changed it and that did nothing… I’m not getting a check engine light, which is frustrating because if I try to pull the codes it won’t throw me any… so it’s a guessing game now. I’ve gotten mixed reviews - anything from a bad catalytic converter to a faulty O2 sensor or idle air controller or a bad head gasket… but my exhaust is completely clean…others say maybe its bad sparkplug wires or other electrical issue (which is a whole other ball game) or possibly bad fuel injectors causing a misfire? HELP PLEASE!!! Any advice is so appreciated!!

Is the idle speed a little higher than normal? I.e. 950 instead of 750.

No, idle RPM is totally normal. It will slightly spike when it hiccups though.

New spark plugs and wires are very routine maintenance things - just like fuel filters. Just replace them and then see where things are.

As to the “list” - yes, lots and lots and lots of things can make a car run poorly. New plugs & wires make sense as a starting point just b/c its routine maintenance.

I just replaced my spark plugs last year, they should be okay… although I’ll inspect them just in case. What else could it be? I’m not sure where to start.

Wires - did I say wires. Oh right - maybe replace the wires.

yikes… okay. thanks.

I think that worked! Thanks for the tip!!!

also try seafoam

sooo changing the sparkplug wires did NOT fix the problem. Where should I look next?

Check the fuel pressure.

I’ll do that… I just called my usual mechanic and he said that a fuel pressure issue wouldn’t normally happen during an idle or acceleration from a stop, more of a highway thing when you’re at high speeds… but I’ll have him check it out.

He said it sounded like an electrical issue… back over the summer my car was stalling due to a rusted air intake wire. It had similar but not identical symptoms then. I’m thinking maybe it’s related to the air intake? Like an idle air controller or the same wires or something?

Yes, its true what your mechanic says about the fuel pressure. But that’s not the point. Your car isn’t running quite right. For the car to run right it needs 4 basic things - air, fuel, compression, and spark. If it starts running funny and you don’t have any codes then you just start with the most basic and fundamental things. Spark plugs & wires; fuel filter; air filter; fuel pressure; vacuum issues. You can start guessing about this and that all over the map if you want, but that is haphazard and will quickly get expensive if you just like to change parts to try them out.

So you just do the basics first. A basic check of fuel pressure is a 10 minute job at most. There’s no reason not to do it & cross it off the list.

The next thing I’d so is put a vacuum gauge on it & look for evidence of a vacuum leak.

After I knew that the basics in terms of air/fuel/spark are in order, then I’d start asking about other things.

If it comes to that your mechanic should have a scantool that will let him/her take a good look at lots of those other things that may be a problem (sensors and stuff).

Thanks, I’ll be sure and report back once I have those things checked. Thank you!!

I had the same issue with my 2001 Grand am V6 it ended up being a corroded ignition coil, so i replaced it and it immediately corrected the issue