Rep Power: 0

I have a 1996 EX auto w/ 159k miles I just bought from a police auction. Has what seems to be the floating idle after warming up. Did the usual Google search and learned it could be something with the IACV. I removed it, cleaned it and the TB real good. Put everything back together and I have the same issue. No issues driving, no misses or anything. I have no vehicle history since it was a seized vehicle.

Could the sensor be shot? Another place I should check? I have looked over everything for a vacuum leaks and have found nothing obvious.

Thanks for any input!

 
Rep Power: 0

Ok, tried something else I read...I started the car and let it run until it started doing the idle flux. Unplugged the IACV and it stopped, but of course it threw a code. Plug it back in and would go right back to fluxing again.

So I am guessing the IACV sensor is bad. Will update if that takes care of the issue.

 
Rep Power: 519

With the engine warm and surging:
Pull the intake snorkel off the throttle body and plug off the open holes with your fingers. Does the RPM drop to correct normal idle or drop to very low idle RPM?

That IAC has coolant hoses going to it.....Does it get hot as the engine warms up, or are the hoses clogged?

Unplug the IAC connector. What does the idle speed do? (You just said it stopped fluctuating, but did the RPM go up or down?)


Try an idle relearn yet?

 
Rep Power: 0

It evened out when I unplugged it...still a little high though. Hoses are not clogged, checked them when I pulled the TB out. The IACV was actually fairly clean, just carbon build up. I was thinking it would be nasty after some of the reading I did.

I will try pulling the snorkel off and see what that does.

How do you get it to re-learn the idle?

Thanks!

 
Rep Power: 519

The idle learn procedure must be done so the ECM/PCM can learn the engine idle characteristics.
Do the idle learn procedure whenever you do any of these actions:

• Replace the ECM/PCM
• Reset the ECM/PCM
• Update the ECM/PCM
• Replace or clean the throttle body
• Disassemble the engine or the transmission

Disconnect the battery to reset the PCM. (hope that radio is not an anti-theft type)
I open the doors or turn the headlight switch on to discharge any capacitors and dump memory from the PCM.
Leave battery unhooked for like 10 minutes.
Reconnect.
Start engine, get it warmed up.
Turn off all electrical items. Trans in park.
Let engine idle for about 10 minutes.


(It's actually supposed to be 5 minutes, but every time the radiator fan runs you have to add more time.)
I might go eat lunch or get coffee while I wait, or go fix a different car.

 
Rep Power: 0

Great, thank you!

Now if it starts doing the idle surge do I just let it keep going for the 5-10 minutes and see if it stops?

 
Rep Power: 519

Did you cork the holes with your fingers yet? What did the idle do?
(This was supposed to make sure the problem is IAC related, and not an external vacuum leak or something.)

 
Rep Power: 0

No, have not had a chance yet...it was 10p last night and kids were in bed. I am going to try that this afternoon.

Thanks!

 
Rep Power: 0

With the tube off it continues with the fluxing idle. If I unplug either the MAF sensor or the IACV it stops and idles at 1100 rpm.

 
Rep Power: 519

Inside the open end of the throttle body you should see an open hole at the bottom. Cork that with your fingers and see what the idle rpm does.

 
Rep Power: 0

Ok...now this is weird.

Started it up, let it warm up, no flux just idling at 1600 rpm. Put my finger over the hole you said and RPMs drop to what sounds like normal (I'm by myself right now so can actually see gauge.) I'm leaving it running right now to see what happens.

 
Rep Power: 0

10 minutes of running, no flux only holding at 1600 rpm unless I put my finger over the hole.

 
Rep Power: 519

Ok so the issue is at least isolated to the IAC valve area.....I"m thinking it may be partially stuck and can't close its passage off completely.

Try tapping on the IAC valve from underneath with something small and solid? (Like a small hammer, but not hard enough to bend the aluminum) If the idle speed drops at all when you do that, it's sticking.





http://www.odyclub.com/forums/9-problems-concerns/27649-diy-cleaning-iac-valve-idle-surge-no-more.html



The small blade between the two air chambers must be completely free to pivot from fully open to fully closed. It only takes a little bit of crap to keep it from closing all the way.


I've had a little success just filling the passage with carb and throttle cleaner and letting it soak a while, but it's not reliable enough to actually call it a guaranteeable fix at work.

 
Rep Power: 0

Great, thank you! I will try that later tonight and see if it fixes it.

I really appreciate you helping and walking me through this!

 
Rep Power: 0

Hammer trick worked! Idles fine now with no flux.

Thanks again for all your help!!!

 
Rep Power: 519

SO that proves it was stuck.

Now at least you know what the issue is/was, and you probably ought to do something about it........because it's likely to get stuck again sooner or later.

 
Rep Power: 0

Going to pull it and see if I can clean it any better. I also ordered a new one for $35 so worse case I will just replace it.