Need help with Free reving at idle

[Dave King]

When I give the car throttle in park from an idle it revs good but it doesn't come down as quick as it should. Can anyone tell me what adjustments I need to play with? My guess is Idle Speed/Throttle Follower but I'm not sure.

 

[bruce]

Originally posted by Dave King
When I give the car throttle in park from an idle it revs good but it doesn't come down as quick as it should. Can anyone tell me what adjustments I need to play with?

My guess is Idle Speed/Throttle Follower but I'm not sure.

Yes, but too lean or too much timing down low can cause part of that.

 

[Dave King]

I played with the Throttle follower and it didnt help any. I'm going to try to reduce timing down low. Anyone have any other tips?

 

[RickWI]

Yes I think your on the right track. Make sure to look at your timing map while bliping the throttle and watch where the cursor gets hung up. Most likely in a higher timing value versus where it idles at. A few degrees less makes a good bit of difference. Also look at the VE screen and make sure you don't have any oddball values there as well.

 

[Craig Smith]

Try adjusting the values in the IAC P and D gain settings as well. These will impact how quickly your IAC motor will adjust to idle speed variations. Don't get them too high, though, or it will cause your idle speed to wander around almost as if it's too lean.

 

[Dave King]

OK, I spent a good amount of timing messing around with this and I still can't get it to work. If I blip the throttle its not a problem. The part I can't get to work right is when I'm going up high in throttle position and then completely back off. The car revs like it should and then sticks around 1800 or so for about 2 seconds and then drops down. I took out timing all around where it was hanging up but that didnt help. Timing is around 15-18 degrees on the cells its hanging at. I tried messing with the gain settings in the idle control mode but they didnt seem to make much of a difference. I also played with the throttle follower and that didn't do much.

What am I not doing right?

 

[RickWI]

Did you look at your fuel map after you did the timing? Look to see what the correction factors go to and then try and dial in as needed.

The P term on the IAC will tell it how far to move to correct the idle and the D term will tell it how fast to move. FYI.

 

[bobc455]

Is your car turbocharged?

I'm a little confused, if you are idling at high throttle position, aren't you gonna be revving kinda high? Or do you mean when you are driving/high TPS?

For whatever it's worth, I have set all of my throttle follower to zero.

-Bob Cunningham