cleaned throttle body, now CEL appears when idle

**harimon21** · August 11th, 2009 10:58 AM

I had the throttle body of my mitsubishi 4G15 cleaned. i was able to remove too much black and sticky substance from the TB and the throttle flap. In the process I had all electricals (sensors) disconnected including the throttle position sensor, and the ones behind the throttle cable, but not the Idle Air Control Valve though. When I run the car afterwards, idle goes upto 1500 on start-up for 5 seconds, then settles at 1000 to 1200 with AC off. When AC is on it is about 900 rpm. Seems a little high from previous setting of 800 rpm. I tried to adjust the idle screw to lower the base idle, but that doesn't seem to work. I have almost completely loosen the screw but the idle is still up. Also the check engine light (CEL) appears when at idle and AC off. But when AC compressor is on or when i step on the gas, the CEL disappears. What have I messed up? the throttle sensor? Other than the CEL appearing and the somewhat higher base idle, engine seems more stable,with less shudders at stop and go after cleaning.
Any ideas tsikoteers? TIA

**bambino** · August 11th, 2009 11:05 AM

things to do here ;

get the engine scanned and go from there .that might be from the sensors disconnected previously or a vacuum leak from the area you worked on causing it .

**afrasay** · August 11th, 2009 11:08 AM

naku if i were you i wouldn't turn a screw in an efi engine. i would rather re check all the sensors that you have taken out and if all checks out i would drive the car a few block and see if the CEL disappear.

**oj88** · August 11th, 2009 12:58 PM

DId the battery get disconnected? If so, I guess the TPS needs to be re-calibrated. Most likely; a) Disconnecting the battery cleared the adaptive idle parameters and/or b) cleaning the TB altered the intake air characteristics. In most cases, it will only require some time for the ECM to adapt to the clean TB. This can take from a few minutes to a few days.

Though to be safe, have it scanned for possible DTCs. Also, they may be able to accelerate the learning process of the ECM using their tool (assuming that's the only trouble).

**niky** · August 11th, 2009 01:13 PM

Originally Posted by afrasay

naku if i were you i wouldn't turn a screw in an efi engine. i would rather re check all the sensors that you have taken out and if all checks out i would drive the car a few block and see if the CEL disappear.

+1... turning the screw does nothing that the car won't return to (ab)normal after a few hours. Check everything, return the idle screw to its previous position, disconnect the battery, drive and see if it goes back to normal.

**speed unlimited** · August 18th, 2009 10:07 AM

It is also better if you clean your IACV and MAF spray with maf cleaner.

**v6dreamer** · August 22nd, 2009 01:53 PM

Check all vacuum lines and make sure one is not dry rotted, cracked, loosed if so that will cause the car to idle to high as well, and also check your pcv valve.

Or......

Maybe your car has a "fly by wire" throttle system, which means it uses an electronically controlled throttle. When you manually force open the throttle body plate it messes up the calibration of the electronic throttle control actuator. You need to take it to your casa and have them do a idle/air learn procedure on it and hopefully that will fix it. If not you will have to replace the throttle body. It will cost you big bucks unless you can convince the dealership to cover if it still under warranty. If you do take it to your dealer do not tell them what you did to your car or they will not even attempt to get it covered.