normally when i start my car the idle comes up to about 1500rpms then slowly drops down to about 750 or so. i no this isnt normal , but i hadnt noticed any problems till today. This morning when i started my car it went up to 1500 then stayed there. i shut it off waited a few seconds then restarted it. then the idle came down and it was fine. then i was going to leave my house after work and it did it again, but this time no luck when restarting it. it will idle between 1500 and 2000 and i already checked my tps and iac which have already been replaced.


My car is my daily driver and i need it to go to work so help is urgent.

 

Is it just READING that it is that high, or can you actually tell by ear that the motor is turning faster than usual?

Reason for asking is because alot of the tachs in 3rd gens (including mine) take a dump after a certain period of time, and read a rediculously high RPM. My car reads 1750 at idle, but I know it's just the tach reading wrong. Apparently at WOT, my engine is spinning at 8000

 

no it is definetly idiling way too high, my tach is only a little off and i no thats not the problem.

 

sounds like the IAC could be sticking open...if it does it again pop the hood and listen around the TB and see if its a loud hissing sound... my IAC was stuck open and it would idle at 2000 rpm all the time and made a loud hissing sound from the throttle body.... you may have to take your intake tube off to hear it since the intake quiets it down alot...

 

I had the same issue I got a new TPS , that fixed it. You should check TPS voltage.

 

He said his TPS and IAC were checked over and are not the issue.

 

i have a scanner, and my tps voltage is about 4.4 at wot and .75 at idle (while idle is 1500-2000rpms) im not sure if thats good or bad.

 

try taking your intake off... start it up and if it does it again.. plug the hole in the middle of the throttle body and see if this lowers your idle.... your IAC may be sticking open it might not be bad enough for it to stay stuck open...but it could be sticking then freeing itself...

at idle the TPS should be about .075 - .54 volts so you are a little on the high side

 

i have a throttle body air foil so that is already blocking the middle of the throttle body. i think i meant to put .075 and not .75. i think i know the problem now.

- a few weeks ago i was washing the engine bay of my car and the hose blew the wire off of one of my temp. sensors(the one in the head on the drivers side.) this caused my car to do the same thing(idle at 1500-2000 rpms) we discoverd the that it was the temp sensor because the scanner said that it was not going into closed loop even at 215 degrees mening the computer is not reading the temperature. now the wire is connected so i am going to replace the sensor and hope it works.

- if its not that than i think my egr is cracked and is leaking vacuum because every once in a while my car will throw an egr code.

-thanks for the suggestions guys