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Discussion Starter #1
Recently truck (95 D90 NAS stock) has had an intermittent idle issue whereby it starts normally then idle drops, never dies, and then back to normal. Truck runs perfectly after that.

Yesterday I replaced the three hoses and restrictor T section. Now it idles high. No vacuum leaks that I can discern. Could this have caused any issues?

I'm going to clean air idle control valve but wouldn't mind a few step by step instructions. I've searched but all solutions simply state; "Clean air idle control valve with carb cleaner and toothbrush".

I'm going to need something a bit more specific starting with its location:grin

Thanks Board!!

KCD
 

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its on the left hand side of the plenum at the back. you can't miss it!

Idle should be solved by AICV ... if it doesn't then next thing to check is throttle cable being too tight or timing
 

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IMO, best to go through the troubleshooting guide than to just attack random bits. Maybe the valve sticking is the problem. Maybe the base idle is set to high. Maybe one of a few sensors is not working problem.

RRC workshop manual has a great step by step guide to check each item.
 

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Now it idles high.
How high?

...and if I recall correctly, UD pointed out something in recent months about the possibility that "running rich" is or can be a symptom of an exhaust leak. Not that I'm really qualified to equate "running rich" & "idles high".

So, just to really hang myself out there, maybe the leaky hoses that you replaced were compensating for some other problem such as an exhaust leak? Anyone?
 

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Mine idled high because the timing was set incorrectly. There are a number of causes and so a methodical approach is best to ensure you don't miss anything.
 

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Discussion Starter #6
How high?

...and if I recall correctly, UD pointed out something in recent months about the possibility that "running rich" is or can be a symptom of an exhaust leak. Not that I'm really qualified to equate "running rich" & "idles high".

So, just to really hang myself out there, maybe the leaky hoses that you replaced were compensating for some other problem such as an exhaust leak? Anyone?
About 1100 give or take...

And they weren't leaking, I was just spiffing up engine bay with new stuff....:hide:
 

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Discussion Starter #9
Yes, that is it on the right with the wires you can see coming out of it.
Wish me luck boys....I'm going in as drink is chilling and charcoal is heating....:thumb:
 

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Discussion Starter #10
OK quick question..

Wish me luck boys....I'm going in as drink is chilling and charcoal is heating....:thumb:

Got the valve out and cleaned up, looked pretty clean actually...

my question is, should I be able to push the valve part in or pull it out when it is off the truck?

In other words, the valve will absolutely not move, in or out.

Is it controlled by the inner workings or should I just grab another one?

Thanks Board!

KCD
 

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It won't go manually without a lot of force and I don't like to force mine. Just plug it into the harness and have some one turn the ignition on and off and you should see it extend and retract.
 

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Discussion Starter #12
Thanks!!

to Jason and Chris and the others!!

Turned out super easy to do with a bit of guidance.

Pulled the idle air control valve, cleaned it with carb cleaner and wife's toothbrush and after a restart,truck is back to running perfectly.

If anyone is having trouble with idle, I highly recommend this 5 minute effort. My only issue was it was on there REALLY tight so it took some oomph to remove it.

Thanks again guys!!

KCD
 

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to Jason and Chris and the others!!

Turned out super easy to do with a bit of guidance.

Pulled the idle air control valve, cleaned it with carb cleaner and wife's toothbrush and after a restart,truck is back to running perfectly.

If anyone is having trouble with idle, I highly recommend this 5 minute effort. My only issue was it was on there REALLY tight so it took some oomph to remove it.

Thanks again guys!!

KCD
Kevin mine sticks just as high on idle more often than not so thanks for posting this issue. Question I haven't looked at mine yet but how does it come off? Is it threaded on or just pull off/outward?

Thanks!
Will
 

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Discussion Starter #14 (Edited)
Will- It just unscrews. Not sure of the size. Lefty loosey, righty tighty... I had to PM Jason because I was putting a LOT into trying to loosen it with no luck. He assured me probably it was just a bit of corrosion and to keep at it. Which I did and it finally broke loose. Might try a little PB or something first. Anyway like I said, kitchen table, carb cleaner, toothbrush and all better.

KCD

Also, to pull off the electrical connection which is in there pretty tightly and which you do first, make sure you release the underside of the clip first. It then just wiggles out. (that's what she said)

KCD
 

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This is a stepper motor. Never force it to move or it will break. I've also seen these fail when overzealous use of cleaner is applied causing the spindle to seize. I use an IAC found on any mid 90's Chevy Vortec V6 for replacement. Cheap, plentiful and it works fine. Grab a couple of clean ones at the junkyard for quick spares.
 
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