Idle Problems

[217gsr]

Recently, I've been noticing some idle problems. When I start my car cold, the idle hunts in a 500 rpm range between ~1500rpm and 2000rpm.

When the car warms up, the problem goes away.

Even more recently, I've noticed that when I come to a stop, the idle does not go down to the 750-900 rpm that it should. Instead, I've seen it idle somewhere around 1300-1400 rpm.

Can someone help me diagnose this problem.

Would bypassing the thermo valve on my throttle body solve this problem?

[cpa]

Weird, my car did this today too. Figured I had my first vacuum leak ever. I can see my vacuum fluctuate on my PMS unit. Hopefully it goes away when I drive home [img]tongue.gif[/img]

Maybe something strange in the air today...

[217gsr]

Definately weird. I did consider a vacuum leak. But I wanted to see what other possiblities were also.

[JRCivic]

A vaccuum leak is the first thing to look at... however, chances are good that the culprit in this case is either the IACV or Thermo valve. I say this because both of these devices are most active when the car is cold... and become far less invasive once the car reaches operating temperatures.

Joe, did you ever call me so I could walk you through the test procedure on this ??? If not, ring my phone babee.

[cpa]

Aaargh [img]mad.gif[/img] ! My idle problem didn't vanish on the way home. Mine won't seem to go below fast idle wither cold or warm. when cold, it idles fine at fast idle around 1,300 or so. Once it's warm, it will idle there, and then try to drop, but once it tries to drop it jumps back to about 1,700, then down to 1,300 and starts the process over.

Would this be consistent with a fast idle thermo valve problem?

[217gsr]

Wow! 2 Thumbs up on that one Jim! [img]graemlins/thumbs_up.gif[/img] [img]graemlins/thumbs_up.gif[/img]

I'll have a couple minutes tomorrow afternoon to do this. I'll definately let ya'll know then.

IF the thermo valve is the problem, the coolant bypass trick should fix the problem, right?

If it's the IACV, then I'm guessing I'll have to clean out (?) the screen, right?

I blame this ALL on Cali's 91 octane gas!!! jk.

[JRCivic]

Yes.
Here is a quick test (pay attention Joe, this will save you a phone call):

First, warm the car up to operating temp. Remove the intake tube at the throttle-body end. Now, look inside the lip of the throttle-body: you will see TWO holes about 1 1/2" back from the lip... the lower one is at the 8 O'clock position... the upper one at about the 10 O'clock position. With the car running, place your finger over the lower hole. If the idle drops to normal and stabilizes, then the THERMO valve is the culprit. If there is no change, you must test the IACV. This is a bit more tricky because if you simply cover the upper hole, the car will probably stall. Instead, slowly slide your finger across the hole so as to reduce the open area gradually. Once the hole is about 90-95% covered, the idle quality should be normal. If you can cover this hole completely, and the idle is still "hunting" (going up and down in a rythmic pattern), then the IACV is most likely the spoiler.

Good luck.

[cpa]

Hey, between this board and the Helms manual, every now and then I learn something or get something right [img]biggrin.gif[/img] . Thanks for the testing tip on the IACV as well.

[217gsr]

Well Jim, after doing your test, these are my results:

I drove the car for approximately 20 minutes, so I know that the car was fully warmed up.

I stopped the engine for about 5 minutes. I noted the engine rpm to be approximately 1200 rpm at idle. It wasn't as high as 1400 rpm like the other day, but 1200 still seems pretty high.

After plugging the thermo hole, I noticed that the engine rpm dropped back down to approximately 800 rpm. Unplugging it brought the engine rpm back up to about 1100 rpm.

What are my options now? Does this absolutely mean that it is the thermo valve or is a vacuum leak still a possibility?
1) bypass the thermo valve? This is only a temporary solution though, I think. I live in California, and will probably need to have my car re-smogged in about 1.5 yrs, so I can live with this solution for a while.

2) Is it possible to buy a new thermo valve?

Thanks again for the replies.

[cooldred1]

Here's a picture of the valve

http://members.aol.com/cooldred/FIT.jpg