My car has had a high idle for a while, and it has always bothered me. It's a 1995 manual and it idles around 1100. When I turn my lights on the idle drops down to around 900. What gives? I know the idle should raise a little bit when the lights are turned on. I am guessing if my AC worked it would do the same thing. I have tried adjusting my idle a bunch of times and it has never been able to go lower than 1100. I have cleaned my IACV, I also replaced my IACV with another used one (this is my only suspect at this point, but when I replaced it, the car acted the exact same way as it did before). What would cause this? I have also replaced my TPS, and I have it set to give me the lowest idle possible (cocked towards the passenger side). I have no error codes in the ecu. Has anyone had this problem? Thanks for any help.

 

have you cleaned your throttle bodies lately?

Also, when you apply an electrical load to your system (rear defroster, lights, ac,etc.) it will always drop your idle a little bit due to the added stress on the alternator making it harder to turn.

 

throttle body is clean. I have never had a car that the idle drops when you turn on the lights...it has always gone up a little bit to compensate for the extra load.

 

You need to adjust the base idle at the throttle plate.

Start the engine and allow it to get to operating temperature.
Turn off the engine and disconnect the TPS.
Start the engine and set the idle speed to 650 using the throttle body default stop screw.
Turn off the engine and reconnect the TPS.
Restart the engine and adjust the IACV if necessary to obtain the correct idle speed.

 

I am going to go look at my Haynes manual now, to see where it is, but like most other stuff with the Haynes manual it doubt its in there. If you have a picture or a good description of where it is I would appreciate it. Thanks.

 

nevermind, I found it. My biggest problem all along is that I always thought the plastic screw on the IACV was the idle screw. So when I was telling people I had already adjusted that I was refering to the wrong thing. Thanks for your help. My idle is now set ~700. When I turn the lights on I have no change in the idle...is this correct?

 

yes, 700rpm is fine for idle.