What are the signs of a bad IAC Valve?

Tom95gt · Dec 29, 2008

My car is stuttering going down the road and the guy at Auto Zone said it sounds like the IAC valve but I don't see how that would be

inphiniti · Dec 29, 2008

sign of a bad iac valve would be stuttering. or at idle it could be idling like ****... i just swapped an IAC on my girls expedition. the truck would idle as if it was cammed out, and soon as you go to drive, it would stall.

it COULD also be that your MAF is clogged.. my maf was clogged with a bunch of debris, i sprayed some of the MAF cleaner in there and it fixed my bucking... the guy @ Autozone could be right. but its also another thing to look into... either way you should be ok and i believe the iac is rather inexpensive.

Tom95gt · Dec 29, 2008

I never thought about cleaning the MAF i'll try that asap

HISSIN50 · Dec 30, 2008

If the issue occurs while you have the gas pedal depressed any decent amount, the IAC is not the issue. And if it idles well, hot and cold, the IAC is not the issue.

saleener94 · Dec 30, 2008

I say spray the MAF with MAF cleaner first. helps alot

Tom95gt · Dec 30, 2008

Well I cleaned my MAF and no difference... to give you guys more details it doesn't do it as much when the engine's nice and toasty actually not at all if I've been driving around for a while and whenever it does it feels like I'm hitting snow banks... it's definitely noticable so if anyone can give me anymore ideas asap it will be appreciated, i'm waiting for it to just poop out on me

p.s. I have a nice exhaust leak by the head but i doubt that has anything to do with it
p.s.s. I replaced my 02 sensors maybe 2 months ago so they shouldn't be bad already

inphiniti · Dec 30, 2008

hmmmm... my only suggestion would be to swap out the IAC valve... it could be getting stuck open/closed every now and again and then refixing itself.. the IACs arent that expensive..

Tom95gt · Dec 31, 2008

Today it got much worse the car would just be a constant misfire so I'm goin to check the cap and rotor I might get another set of o2 sensors

HISSIN50 · Dec 31, 2008

Did you pull codes and fix that exhaust leak? The leak can affect O2 readings.

Pull the cap and check inside the bowl for signs of damage to your PIP.

Tom95gt · Dec 31, 2008

Another update took car out after 2 hours and run's fine its so confusing it has to be a sensor
I pulled codes but I'm too dumb to count the beeps lol I think one came up saying o2 sensor running lean... do you think thats because the exhaust leak? I think it was doing it before I developed the leak. I haven't gotten around to fixing that. I pulled the cap looked at the rotor it looked fine, maybe a little corrosion. I don't know what to look for concerning the PIP

revhead347 · Dec 31, 2008

HISSIN50 said:
If the issue occurs while you have the gas pedal depressed any decent amount, the IAC is not the issue. And if it idles well, hot and cold, the IAC is not the issue.

Not true, I've had a bad IAC cause my car to jerk and studder while cruising at highway speeds.

Kurt

final5-0 · Jan 1, 2009

About cleaning the meter

Just to be sure there is no misunderstanding

The idea is NOT to clean the inside of the meter

The idea IS to clean the tiny wires inside the electronics box

You have to take the box apart
to get maximum benefit from cleaning those wires

IMPORTANT ... You DO NOT wanna break those wires
and
They are quite fragile ... so ... Be Careful

I know ... I know ... This is so obvious to a lot here
but
We got less experienced folk joining us here daily

Grady

legalize420 · Jan 1, 2009

have you checked the plug wires? pull them off one at a time and make sure there are no burns or cuts.

Tom95gt · Jan 1, 2009

I have read the How-To Clean you MAF thanks Grady and another update drove it around all day today and no problems I'm stumped

Tom95gt · Jan 12, 2009

Well while I was replacing my clutch cable, out of a hunch i decided to see if my dizzy was tight and it turns out it was fairly loose. So i tightened it down and so far so good no stuttering or pinging yet. I guess that could have been the problem?

HISSIN50 · Jan 12, 2009

Tom95gt said:
Well while I was replacing my clutch cable, out of a hunch i decided to see if my dizzy was tight and it turns out it was fairly loose. So i tightened it down and so far so good no stuttering or pinging yet. I guess that could have been the problem?

Where was the timing at when you got a timing light on it? For studdering, it was probably very retarded.

Tom95gt · Jan 12, 2009

That i am not sure about... i think it was retarded but i didn't use a timing light because their wasn't one available so i spun it counter-clockwise and it sounded bad so i spun it clockwise and once i went down the road it was pingin so i turned it back some and now it's perfect from what i know

spock2001us · Jan 13, 2009

when my IAC last went bad it would not hold an idle whatsoever....it was a constant stall. After the stall, it would start right up, but unless I held the throttle open slightly, it was an immediate stall. I replaced the MAF cause it is so cheap, but it was still a stall, would not hold an idle whatsoever. I replaced the IAC and that was exactly what the problem was.

Any idle issues I have ever had have been corrected by replacing either the IAC, MAF, or the TPS or all three because they are so cheap to replace.

Oh, and I also had a problem before when my dizzy came loose. Can't correct it properly without a timing light...in my opinion anyway. Stall and tough start was a result of a bad stater on the dizzy too.

Chris 03 GT · Sep 20, 2015

I'm having the same problem too. Just bought a 2003 GT. It was sitting for a year untouched. I was thinking bad gas? But I've added stabilizers to the gas. Cleaned MAF Sensor and changed Fuel rail sensor bc my codes were P0190, P1150, P1151,P1152,P1131,P1132. Any solutions??

revhead347 · Sep 20, 2015

Clean the ac out and see if it helps. It's not long term fix but it will at least let you know it's the isc.

Kurt

What are the signs of a bad IAC Valve?

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