rough idle

[SomethingRandom]

I searched the forums, saw some similar problems, but all were coupled with other issues I do not have.

I have the 98 AV6, and fairly regularly when I start it (cold, hot, does not seem to make a difference) it sputters and drops to 250-300rpms, flutters around there til I give it quarter pedal for about 10-15 seconds then it settles right down and pegs at 630-650.

From some of what I read, sounds like the IACV or TB could be the source, neither of which I have touched yet, wanted a chance to ask a few questions first. Oh, and I doubt its fuel related problems, I run injector cleaner through the system every so often, also just seafoamed the engine about a month ago.

Thanks for any input guys, hopefully will keep me from postwhoring

 

[Valet]

Yeah if I were you I would start by cleaning the throttle body. Couldn't hurt.

 

[001Stunna]

Before you clean the TB try this...

-Get in the car and press the gas pedal a few times with the car off. Does it feel like it was lodged or hard to press the first time?
-Start the car...does it still do the rpm shudder?
-If Yes...then follow by taking off the intake and cleaning the TB with a rag and some TB cleaner. use your fingers and go as deep as you can (in the TB that is) with the rag. Clean the flap by opening and closing the TB with ur hand. Let the car sit for a bit and try starting it. The car might be a bit hard to start after so if it doesnt start first time, try starting it with the gas pedal all the way down.
-retry for the rpm shudder
-if it still persists clean the IACV as well.

 

[Frisky Arab]

Let my uncle drive it. My car was doing this exact same thing about a week ago. Got to a point where it would sputter and die if my A/C wasn't on to keep the idle just that tad bit higher. My uncle drove it to work and back and it got home good as new. Has been fine ever since.

 

[419superman]

fuel injector cleaner should help, check electrical connections, mine sputtered because the negative battery line was lose;

 

[Brimstone Brown]

I had a similar problem recently. I cleaned tb,iacv and the egr runner using info I found in the diy section. Took care of my problems.is your check engine light on.if so what codes is it throwing?

 

[SomethingRandom]

It never threw any CEL's, took me two weeks but I finally got around to pulling the entire TB assembly off. A previous owner had cleaned it without changing the gasket, f**king thing took an hour to scrape off with a knife. Idle seems a little smoother, only time will tell.

I tried taking the IACV off as well, screw heads were nearly stripped, but it looked ok after I blasted it with TB cleaner and hit it with the toothbrush.

Thanks for the help guys, IM will be coming off sometime this summer when I have time for a good cleaning, so I'll prob do the EGR as a precaution at the same time.