dudemanguy222

i had this problem and had a new idler valve installed. worked for me. lol

Cosmo Kramer

I tested mine on the bench and it was opening and closing no problem.

Does anyone know if these valves can leak air in the fully closed position?

WallyP

Have you checked the idle speed with a known-good tachometer, rather than the dash tach?

Have you checked and double-checked to ensure that the throttle plate isn't hanging open slightly? Don't depend upon the idle switch to tell you this!

aggravation

On the S4 the idle valve doesn't have a "fully closed" position. It has a default slightly open position when not powered. this may not apply to the older cars though.

Also, on my S4 I was able to reduce my high idle by retarding the ignition maps for idle and warm up. To get it smooth and all the way down to 750 rpm I also restricted the opening in the air cowl that feeds air to the idle valve by approximately 65%....both of those steps were required to get it right. I still don't know why it was high.

Cosmo Kramer

Hey Wally

Throttle is not hanging up and I have slack in the cables, so no issue there.

Took the car on a 250 mile trip yesterday with the family and now the MAF is in spec it ran AWESOME other than the high idle.

I am going to borrow an infrared tach and check it against the one in the dash.

Since the rest of the car runs well other then the high idle, I am starting to wonder if it could be the TPS adjusted too tight and holding the plate open slightly as per this thread.

Craig: So are you saying the TPS adjustment didn't resolve your issue?

Imo000

Ted,

I’m glad you are making progress. The throttle linkage (after the cables) is what you need to also check. You can have loose cables and a tight linkage (keeping the throttle valve slightly open). I would pop the linkage off and see if the idle drops. Just make sure to remove the safety retaining clip/spring that’s at the bottom of the linkage ball, then you can easily pop off the ball socket. Also, if you are up to it, you can try and swap out the idle air controller with my spare one to see if it makes a difference.

Cosmo Kramer

Hey Imre

Checked the linkage, popped off the ball no hangups.

I may try your IAC, I have pulled it out once before (gotta love the position you have to be in to get it out)! When I pulled it out the last time my wife asked if I wanted to be left alone with the car LOL!

Imo000

LOL…. BTDT!

I’ll try to squeeze in a couple hours of 928 work tonight so if you want, come by and we’ll get the IAC off the spare engine.

aggravation

Yes, sort of...
I believe it did add to the problem slightly but it was still too high after getting it set up correctly.
I'm not sure what all the factors were that created my high idle because once I found a way to make it stay at around 750 I quit searching and started just enjoying it.
I had tried so many things that I finally gave up and did what I knew "worked" even though I may have simply compensated for the problem rather than solve it.

I still plan to do some final SharkTuning for the cruise and WOT maps and once that is done I'll see if my compensation method is an issue...if not I'll leave well enough alone.

What I did was I took a 90 degree 3/8 OD copper "street fitting" (one that is female on one end and straight tubing on the other end)...cut a 1/2 long inch piece of rubber fuel hose and slipped it over the female end of the copper fitting (the ID of the hose is tight on the OD of the copper female end)....with a pair of long nosed 45 degree pliers grab the straight end of the fitting and work it, female end w/hose first, into the 'Y' fitting from inside the air cowl outlet and into the leg of the 'Y' that feeds the hose to the ISV. That way the other leg of the 'Y' isn't restricted, only the ISV leg is.

By just removing the MAF I can put it in or take it out. That restriction combined with the retarding of the ignition timing in the warm up and idle maps it makes my idle sweet at 750rpm's. In theory it should have no affect on the cruise and WOT fueling.

Cosmo Kramer

OK, I am borrowing a timing light and infrared tach from a friend today and gonna check some things out.

When I started this high idle project, I disabled the ISV and the RPM's went up which was kind of confusing (Mike Frye had the same thing on his 85). Now that the MAF has been set to spec, I disabled the ISV again and the idle dropped 100 rpm and the idle became more lumpy, almost like it was too low (even though the dash tach still shows 1000 rpm).

It will be interesting to see what the external tach reading indicates. I will report back what I find out.

Cosmo Kramer

Borrowed a timing light with an external tach, the pics speak for themselves!

Anyone with a high idle needs to do this just to be sure. The exercise of diagnosing it led me to the out of spec MAF, so that was a good thing.

At least I am not chasing this anymore, now how do I make the dash tach more accurate, it is out by over 30% at idle!

PorKen

Too funny.

Where does the needle rest when the engine is off? You can move all of the needles on their axles, they are just friction fit. (Rotate the needle to it's stop, then gently push a bit farther.)

IIRC, there is a mark on the outside of the dial face where it should point at rest.

Cosmo Kramer

Rests just below the first mark. The speedo is out by 6 km/h too so maybe I need to do both.

I have to pull the pod anyway to do an odo gear and fix an intermittent speedo (it quits and I tap the pod, starts up again) so I will adjust the tach WIAIT.

The tach bounces when the car shift gears at WOT, like on the 1 - 2 shift it comes down to 3 and bounces back to 4 and climbs. Is that normal?

Imo000

The speedo is probalby calibrated at the factory to be out a little. All car read more than the actuall speed. 6km at 100km/h is normal.