Another Rough Idle Problem [Archive] - GrandAmGT.com Forum

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dennistowell
02-27-2004, 12:23 PM
Well i did a search and found some info but all i found was for idles that were not that bad. Mine seems to be the worst i have found yet. When at idle my car jumps from 300 to 1200 RPM and back and forth. It seems like it wants to stall but i wont let it, i just sit with the brake on and hold in a little gas and it seems to run fine at like 1500 RPM. When drivng it runs like a champ, the only problem is when at idle, it even runs fine when i let off the gas and am just coasting. Just wondering if this is a problem i should try and tackle or if it is just a better idea to take it in to the dealer.

The problem just started today and i didnt notice anything untill now. If it matters i have a drop in K&N, exaust, and removed MAF screen. Any help????

Blackrider
02-27-2004, 01:53 PM
Possible Idle Air Controller problem, If you take it to the dealer and that ends up being the problem they will try and blaim it on your Air Filter

dennistowell
02-27-2004, 03:27 PM
well took it to the dealer, and just my luck it ran perfectly fine when i got it there. they charged me $72.00 to hook a scan tool up to it and put a fuel pressure gauge on. Then the guy told me since it was moving from 47-50 psi while idleing, that my fuel pump was going out and they needed to change it for about %515. I was not about to do that so i told them since it was running fine i would take it for the weekend and if it started doing it agian next week i would bring it back in.

Any thoughts on what it could be. is that guy right, just because it was moving 2 or 3 psi that my fuel pump is bad. anything that i could check myself that could be causing this?

Blackrider
02-27-2004, 03:35 PM
I HIGHLY Doubt its your Fuel Pump man. You said it was running fine when you brough it in right? and when he hooked up the FP Gauge to it its was fluctuating 2-3PSI? So I dont think this is a Fuel Pump problem, Maby a regulator. I'm Still thinking Idle air controller. If you have ever over oiled you filter this can cause problems with the IAC, You might want to try cleaning it.

The reason I'm leaning toward the IAC is because I had the same problem, it go to the point that it just Idled at 2500, I Cleaned it and it was good for about 200KM then it did the same thing, So I just replaced it with an extra IAC i had around.

balludc
02-27-2004, 03:37 PM
i was under the impression that fuel pumps either work or dont work. since we have electronic fuel pumps, why would it be "going bad".

my uncles lumina had a fuel pump problem... it idled bad then one day the pump just stopped working. i dont think that will completly solve the problem. i'm sure its something else. good luck though.

might check out your injectors if the mechanic says theres a fuel pressure problem. i dont know though...

-dc

Blackrider
02-27-2004, 03:41 PM
Ehh, Really clogged injectors might/if at all cause an increase in fuel pressure, a regulator would be more to blaim.

Gt00
02-27-2004, 05:00 PM
Probably a gummed up IAC , like Blackrider mentioned .:)

Irate
02-28-2004, 08:28 AM
moved to technical Q&A :thumbs:

GCarr99GT
02-28-2004, 12:59 PM
Sorry, you've probably got to buy a new MAF sensor. Removing the screen is a bad idea as it straightens the airflow so the sensor can get an accurate reading. Sometimes when it is removed it causes turbulence and will cause your car to idle just like you're describing. I should know; the exact same thing happened to me a few days after I removed the screen. I replaced the MAF sensor (about $90) and all was back to normal. By the way, removing this screen will not give you ANY performance gains, so don't worry about losing any performance when you replace it. Also, since you have to buy a new MAF sensor anyways (you can't just buy the screen), I would look at getting a Pro-M MAF sensor for some added performance with your aftermarket exaust :) . You can find threads about it all over this site.

Blackrider
02-28-2004, 01:09 PM
I dont think i have herd of anyone including myslef having idle problems due to a Removed maf screen.

dennistowell
02-28-2004, 01:16 PM
well i did what most of y ou were telling me to do and i took out the IAC and cleaned. The thing was so dirty and gummed up that i could not even tell it was metal untill i got all the nasty black stuff off of it. Since i could not get to the back screw on the IAC very well i ended up taking the whole throttle body off and cleaned it up as well. Now the car it back to idle perfect agian. i am just happy i dont have to spend like 500 buck to replace the fuel pump.

Blackrider
02-28-2004, 02:44 PM
Originally posted by dennistowell
well i did what most of y ou were telling me to do and i took out the IAC and cleaned. The thing was so dirty and gummed up that i could not even tell it was metal untill i got all the nasty black stuff off of it. Since i could not get to the back screw on the IAC very well i ended up taking the whole throttle body off and cleaned it up as well. Now the car it back to idle perfect agian. i am just happy i dont have to spend like 500 buck to replace the fuel pump.

Sweet man Glad to hear, You should go back to the dealer and rub it in that Techs face :p

Just go easy on the K&N Oil :)

Also the best way to get the IAC back into the TB is to take the o ring clean it up and put it in the IAC Port on the TB then slide the IAC itself in. :)

dennistowell
02-28-2004, 02:53 PM
oh well i am going to rub it in the techs face on tuesday when i go back and have my oil changed. The dealership here runs a speacial on tuesdays you get a oil change and 2 free movie passes for 20 bucks. i cant wait to see the techs face when i tell him it is running just fine now.

fast_ga
02-29-2004, 08:46 AM
Sorry to hear you have some dumb techs at your dealer man!lol
And that fuel pump story what a crock! Its possible for a fuel pump to slowly go bad and for fuel pressure to act very strange, but 2-3psi is not a big deal. Hey i do that stuff for a living and if i worked for that dealer id of had ya in and out and fixed in like 20 seconds lol Anyhow glad to hear ya got it figured out and it didnt cost you $600 or more!

dennistowell
02-29-2004, 02:24 PM
yeah the funny thing what it was only at idle, if we would rev it up using the throttle body the pressure would level off at about 50 every time and stay there. the only time it would move is when idling and even then it was not that bad