High idle with Stage 4 SNS chip

[jgcable 0]

My 90 Corrado is fully stage 4. It has an SNS Stage 4 chip in it.

All of this work was done by the previous owner. This included the correct cam, pulley, Stage 4 compressor by KompressorKanada, ISV Reroute, charcoal canister delete, 3.5 bar FPR, Eurosport intake etc...

Car has no vacuum leaks that I could find and it runs like a monster.

Since I bought it, the idle sits at a consistant 1100 rpms. Whether hot or cold. Its always at 1100 rpms.

When I blip the throttle the rpms increase immediately but when I let off they drop to 800 rpms and then immediately jump back up to 1100rpms. This happens every time.

I read a thread here that mentioned that the SNS Stage 5 chip sets the idle at 1100 rpms. I was wondering if the SNS Stage 4 chip does the same thing. It doesn't appear to be a vacuum leak or a dirty ISV ( I cleaned it anyway). It seems more like a computer command coming from the SNS chip.

[jackvine 0]

When you first got it did it run fine?

 

Mine did this and I removed the throttle body and totally cleaned it and adjusted the throttle cable, now idles fine.

Also try pulling the throttle pedal back see if the butterfly is getting stuck open slightly.

[jgcable 0]

Car has always run great. I bought it a few months ago.

I will check to see if anything is stuck but even if it was.. what would cause the idle to drop to 800 and jump back up to 1100 everytime I rev the motor.

Let me explain better.

Idle is at a consistant 1100rpms whether the motor is cold or warm.

When the engine gets rev'd, instead of returning to 1100 rpms, it goes to 800rpms and immediately jumps back up to 1100.

[jgcable 0]

Update because I still haven't solved this problem!

I did that idle adjust procedure and I adjusted it down to 950rpms. The same thing is happening. When I blip the throttle the RPM's don't return to 950. Instead of returning to 950rpms they dip for a second down to 800 and immediately jump back up to 950. Idle is smooth and consistant whether hot or cold. Motor has no running issues at all.

I replaced the blue coolant sensor and I checked for vacuum leaks and I couldn't find any. I also cleaned the ISV. It wasn't dirty.

My car has a Stage 4 KK compressor, RSR charger outlet, 268 cam, 68mm pulley, SNS Stage 4 chip, ISV reroute, charcoal canister removed, 3.5 FPR, Borla exhaust, Eurosport intake.

The guys at SNS think its a vacuum leak but my car really doesn't have many hoses and all the ones I checked looked fine.

Idle switch is working properly. ISV is working properly too. Idle is not sticking.

Are there any common vacuum lines that could be leaking that I didn't find? I don't have many because my charcoal canister has been removed.

All the ones I could find are in fine shape.