Idle speed issues...

[AcIdBuRn02ZTS]

Hey guys...

I've been having an issue with the idle speed on this car since I got it running a few weeks back... it doesn't misfire and it isn't throwing codes...

Sometimes when you press in the clutch to stop at a light or something along those lines, it will idle down hard.. (its stalled a few times)... others it will idle down but catch and hover around 450-500... if sitting in a drive thru or something (at a stop for longer then a minute or so), it may start out idling around 450... but will gradually come up ro 750-800 and be fine until I take off again...

Now it doesn't do it every time... but most of the time.

Could the idle air control need cleaning? TPS out of adjustment maybe?(would that throw a code?)

Thanks guys
-Chris

 

[Nick M]

Now it doesn't do it every time... but most of the time.

Could the idle air control need cleaning? TPS out of adjustment maybe?(would that throw a code?)

Thanks guys
-Chris

There is a specific code that lets you know the TPS is out of adjustment. There are contacts inside that pull to ground to let the PCM know with certainty you are not on the accelerator. This answers your question about TPS.

It takes many miles to have carbon build up inside an idle control valve. If it is running low in your driveway, lightly tap on the solenoid and see if it straightens up. That is your cheat sheet answer.

 

[AcIdBuRn02ZTS]

It also takes extended cranking to start when cold... maybe 5 seconds instead of firing in a few rotations of the crank. This morning, when it started, it was idling around 1300... I'm leaning towards the idle control valve.

This car has ~135k on it... it wasn't maintained well and had been sitting for 6+ years when I pulled it home.... it looks like its had a head gasket job done but I can't swear to it... it runs really good now other then the return to idle issue.

Is it a pain to pull the idle air control valve?

 

[Nick M]

Hard start cold is almost always mechanical to include fuel pressure. No reason to pull the idle control valve until you have reason to believe it is sticking.

 

[AcIdBuRn02ZTS]

Ok... so if its not the TPS... and its not the idle air control... what would cause the car to idle at random speeds (no hunting or surging... smooth idle) sometimes at 450... sometimes at 600... sometimes at 750-800....

 

[hvyman]

Did you check for stored codes or just if the cel was on?

 

[AcIdBuRn02ZTS]

I pulled codes.... nothing but the "all clear" code... and no cell currently.

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[supraguy@aol]

When you turn off the car, do you hear a sound from the idle control valve a second later?
I describe the sound as....'Ducka-ducka-duck". That's the valve resetting.

 

[AcIdBuRn02ZTS]

Haven't paid attention to it but don't recall hearing a noise after shutdown . Right now, the egr cooler hose is blown so I'm not driving it. I'll listen for it after I get it back together hopefully tonight.

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[hvyman]

When you turn off the car, do you hear a sound from the idle control valve a second later?
I describe the sound as....'Ducka-ducka-duck". That's the valve resetting.

That is a excellant description sir.

 

[AcIdBuRn02ZTS]

Got it back together... 4 distinct knock sounds upon shutdown.. ducka ducka ducka duck... lol

Tried to pull codes again and had a 42 stored... speedo doesn't work either.. could this play a part?

Other then that, nothing.

 

[hvyman]

Can take the iac off and clean the one way valve and the motor and verify operation like the manual says.

Also check to make sure the dash pot is adjusted correctly.

 

[AcIdBuRn02ZTS]

Will do... it will probably be a couple days before I have time but I'll report back. Thanks for the info.

 

[suprasick]

My does the same and it started when the speedometer stopped working. $10 bucks and a reach around says you fix the speedometer, you fix your problem.

 

[kakanator]

I am having the same exact thing but only when the car is fully warmed up and like the op said lights just stopped things like that. All the way down to 400 or so then it will go back up to 750 ish. My das pot is good tps is good no codes they i can pull. I haven't checked the iacv yet and don't think I hear the ducka ducka ducka anymore.

 

[AcIdBuRn02ZTS]

Guess I'll look into the speedo... most likely just a cable. That's been pretty low on the priority list since dragging this car home.

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[MarkIII4Me]

My does the same and it started when the speedometer stopped working. $10 bucks and a reach around says you fix the speedometer, you fix your problem.

Mine is doing something similar and my speedometer is working just fine. You can keep the $10. :naughty: