Ok, I'm getting a little stumped on this one. Reset the PFC, started learning process with car completely cold. Started it up, it idled around 1100, dropped to 780ish on the commander and didn't move again. Started turning on the load/doing that portion and it'd jump up then smooth out. Eventually it was smooth and fine during all of the transitions to electrical/etc. No issues at all until I went to go for a ride. Put the car in reverse and the idle jumped to 1400 and stayed there. It didn't hunt or fluctuate it just stayed there. Put it in neutral revved few times and it would drop down to about 850 then instantly jump up to 1400 and stay there. I ignored it and went for a drive just to see how it was and everything was fine. Cruise/etc was perfect. Every time i'd come to a light/stop he car would drop to 850 immediately on decel, then it would jump straight to 1400 and stay there. When I came back I discovered that after it jumps to 1400 if I wait a minute or two it'll drop down to 780 and idle ok (a little on the rough side), when the fans kick in at 780 the idle will jump slightly to around 880 and it's fairly rough. Then I could rev it up and down and it'd come back down to the 780-880 range depending on EL. Go for a drive and immediately it does the 1400 thing again. I've gone over everything looking for vac leaks/etc. All sensors look good and I can't see any difference between the sensor check when it's at 1400 or 780. Pretty much completely stock as far as vac lines/accessories on the block. I've got some plates I'll be installing later to block everything off but I wanted to get everything all set and happy before then. Had a high idle of about 900-950 with the stock ECU but it was always consistent.

 

Do you have a lightweight flywheel?

 

Have you adjusted the air screw on the drivers side under the uim. Sounds like it just needs closing down a tad. Hope it is something this easy.

 

Stock flywheel that I know of, but I've ran into a LOT of surprises as far as stuff that was upgraded on the car! I've got that air screw about 1/2 turn out as per the FAQ. I can verify that adjusting the RPM in the fields changes the values when it's idling right, changing those up a few ticks made a huge difference in the smoothness when it does idle normally. I'll try dialing the screw in and seeing if it has any effect, it's just a pain to diagnose because it goes back down to normal after only about a minute of being high like that, there's no hunting at all though so i'm kinda stumped! Thanks for the suggestions though.

 

Make sure the clutch switch is good - the one that's way up in there. The computer uses that and the neutral switch to determine if the car is in gear or not. Long time back I unplugged mine for whatever reason and the car did some REALLY weird stuff at idle.

May not be it, but it's worth checking. Actually, just go to the Etc-Monitor screen where it shows all the inputs/outputs and see if the dot for the clutch pedal goes on and off when you work the clutch, same for the neutral switch.

Dale

 

I dont have my neutral safety switch hooked up and no problems here.

 

How clean or dirty is your throttlebody?Have you checked the dash pot?lastly have you checked the thermowax?

 

Checked the dashpot, thermowax seems fine. If the throttle were hanging up at all, wouldn't the TPS reading be higher during the 1400 period? Because it's exactly the same as when it's idling normally.

I've already checked all of the switches on the Sensor Check screen, clutch/brake/neutral are all working good. I'm starting to wonder if I have a vac leak that I just can't find.