Higher idle than desired with supercharger install?

[Serfma]

Learning to tune myself and got a base tune thus far, but now my issue is that I am forced open loop with RPMs hanging at 1600-2000 at idle all the way until warmed up. I am wondering if dashpot / idle settings need to be tuned to reflect the additional (educated guesses) air at idle that the car is seeing with the blower on top. Sitting at ~1.4v for vmaf at idle.

CDAN4/LLX3, 96 Cobra w/ 2.1 Kenne Bell, long tubes, EGR deleted. Tune has EGR deleted, spark tables set, fuel tables set, maf curve in progress of being dialed in.

 

[01yellercobra]

The dashpot is for engine decel when driving. It won't affect idle while warming up.

How does the car idle once it's warmed up?

 

[Serfma]

The dashpot is for engine decel when driving. It won't affect idle while warming up.

How does the car idle once it's warmed up?

No matter what it sticks around 1600rpm - 2krpm. It does sometimes sit high idle at 2k then drops to 1600 ultimately.

 

[01yellercobra]

That sounds like you have a vacuum leak.

 

[Serfma]

I've smoke tested the intake, no leaks.

 

[01yellercobra]

You have air coming in from somewhere. Even a way out of whack idle setting shouldn't cause it to idle that high. Is the IAC good? Have you adjusted the throttlebody stop and/or TPS at all?

 

[Serfma]

You have air coming in from somewhere. Even a way out of whack idle setting shouldn't cause it to idle that high. Is the IAC good? Have you adjusted the throttlebody stop and/or TPS at all?

TPS is showing that TB is closed. Unplugging the IAC does nothing but I can try swapping it out to see. Unsure though about throttlebody stop or TPS. Same throttle body as last time.

 

[2003RedfireVert]

I’m trying to figure out why my car idles at 1000-1100 even though my idle setting is 750. Same as you, no vaccuum leaks, tb is closed. I’ve adjusted some IAC settings to no avail. Interested to see what you find out.

 

[01yellercobra]

I'd make sure the throttle body isn't stuck open somhow. Just because the TPS says it's closed doesn't mean it is.

 

[01yellercobra]

I’m trying to figure out why my car idles at 1000-1100 even though my idle setting is 750. Same as you, no vaccuum leaks, tb is closed. I’ve adjusted some IAC settings to no avail. Interested to see what you find out.

I don't remember if the stock set up has an idle timing curve. If it does it might be worth messing with that.

 

[2003RedfireVert]

I don't remember if the stock set up has an idle timing curve. If it does it might be worth messing with that.

Yeah, I've checked that as well and even messed with it with no avail. It's only at idle. The rev down, the 1000-1100 rpm while coasting, etc are all good. I've lowered the duty cycle for the IAC valve several times and it helped a little so maybe I just need to keep lowering it...I'm not driving it anymore until spring. I'll mess with it again when I load my E85 tune this spring.

 

[01yellercobra]

The only other thing I can think of is a VSS setting. I had mine set up to hold the higher idle until I was at a complete stop. After dealing with a stalling issue with my 01 I errored on the side of caution. So I had the idle sit at 1000-1100 rpm until the car was stopped. Then it dropped the rest of the way to 750.

 

[Blown38]

What is the IAC duty cycle at idle in the log? What is the timing in the log? If the IAC valve gets put on backwards it will have a high idle.