IAC 00 - redux

[krazy86t]

I've read a few posts on possible causes when IAC = 00 in P,N. Could be vacuum leak, TPS >0.46, bad IAC sensor, throttle blade adjustment. My car has TPS @ 0.44 and new IAC sensor/actuator. When engine is cold and trans in P,N the IAC counts are 30-40 upon start-up, and the IAC counts gradually drop to = 00 as engine comes up to 160 deg operating temp. my car has a standard TT chip

Checked for intake/hose leaks by pressurizing the turbo-intake with compressed air. I found several small leaks (small bubbles from soapy water at 10 psi) on hoses, connections and most I was able to fix with new hose or zip ties. My billet vacuum block did not have the metal fittings sealed with locktite, so i took it apart and improved the fitting seal. No change in IAC values after all of these fixes. tried 1/4 turn CCW throttle blade adjustment and TPS adjustment, but that did not help and i the car idle seemed worse.

Checked for more leaks and found one on the EGR valve acuator rod - it faintly hisses under 10 psi pressure. this EGR valve was replaced last year. Could not find any leaks around upper intake/doghouse seal, throttle body seals, throttle shaft seals. (I pulled the EGR valve off to look at it and was surprised to find dirty/oily residue in the upper hole and a little bit on the valve plunger. usually this area just looks like dry, black exhaust residue. could be a separate issue?)

 

[krazy86t]

Update - With engine warm i was able to get IAC counts 15-25 by adjusting throttle blade screw farther CCW (~1/2 turn). Had to reset TPS to 0.44 closed throttle and 4.50V WOT. Reset the ECM because low TPS signal between adjustments produced MAL code 22. Re-programed TT chip to previous settings (slightly added fuel for WOT).

WOT O2 readings used to be 750-800 mV prior to throttle blade and TPS adjustment. Now O2's are 650-710 mV at 3rd/OD gear WOT, and the chip is pulling 2-6 deg of timing. Did this slight tweak of the throttle blade increase air flow into the intake, so now i need more fuel?

 

[TurboDave]

I really rather doubt that little bit of an adjustment would have made that much of a difference. Something else has caused the leaner readings. But be that as it may, you IAC and TPS is perfect now, so just keep life simple and go into the chip and add more WOT fuel.