belairbrian

Been chasing a slightly high idle between 75 and 100.

When warm the ECM is showing a 625 desired idle while actual is between 700 and 725. This is coming from tuner pro monitoring.

The only thing I can find is that at some point in is life the coating from the butterflies was cleaned off. Thus there is some air passing them.

Could that account for the higher idle?

Also the IACV count is at 0 with 2 different IACVs.

I believe the back of the butterflies should look like this:

383vett

I've never seen coated butterflies before.

belairbrian

There is a warning about it in the FSM.

Tom400CFI

That is crazy (from the FSM and your photo). Like 383, I've never seen any such thing either. My '92 doesn't have that coating, my '89 doesn't have it, and an '85 F-bod I had didn't have it either. Never seen it, heard of it, and I don't believe it would matter.


Weird thing is, if you do a GOOGLE IMAGE SEARCH for "TPI throttle body", none of the pics have that coating, either.

WVZR-1

DAG is likely better understood after this reading:

http://www.zr1specialist.com/HAT%20W...tle%20body.htm

383vett

The stuff looks like it would decrease air flow. I would remove it. Just like porting a throttle body.

belairbrian

Interesting read. He describes the exact symptom i am having.

"Loss of the Dag coating can cause excess air leakage past the throttle plates and loss of idle speed control range for the engine control system"

The picture I posted is a un-used throttle body taken from a 94 crate motor.

belairbrian

I wonder if it was originally only applied to the edges then later applied to the back side to improve adhesion.

belairbrian

I've been lying in bed with a touch of flu or flu like crud, for a couple days. Feeling better now. I wasn't ignoring the posts.

Anyway, I new this was an issue with Hondas. (Yes, I own many Hondas) Causes the same problem.

Might buy that TB I pictured. It looks a lot like a 92 except for the IACV mounting and the extra cable connection on the throttle quadrant.

belairbrian

Well I ended up getting the throttle body. It was a 94 crate motor take off so I had to swap over my IACV housing. But other than that it fit correctly.

After I got it back together the idle dropped down to between 625 and 650. Hard to get an exact read in tuner pro since it reads in increments of 25. The IACV count is now 15 with the engine fully warmed (so the IACV is now controlling idle).