High idle when motor cold
 

every morning when the motor is cold and i start my car up i get the normal 3k rev then it goes down for a second and after that goes back up to 2000-2500 rpms and stay there for a good 30 minuets even after driving around for a while. the only time the motor idles at 750 rpms is when the motor is really warmed up...is this normal?

Accelerated Warm Up system present in FC's will do that. Try starting your car in gear with the clutch pedal depressed. That should cure your high idle.

The AWS will do that, but not for 15 minites. Furthermore, depressing the clutch and placing the car in gear is the way to disable the AWS.

is there a fix to cure the high idle? i know the 3k rev at start up is normal but even after driving around for 5 minutes it still idles at 2000-2500rpm's. thats what im concerned about.

When it's warm where does it idle?

Mine idles at around 800 - 900 when it's been driven for awhile. After I installed my Cold Air Intake it was idling at 1100 after warm-up but I tightened everything down and double-checked the AFM or MAF or whatever that giant brick is (the door-hinge kind for s4's) and now it idles like normal AND it feels great after 4k. (Thanks to the intake.)

EDIT: Meh, maybe I should read the first post, eh? I have no idea what to suggest to you, man.

Cheers,
iSP33D-for-J3SUS :bigthumb:

when my motor is fully warmed up, it idles at 750-900 but ONLY when its fully warmed up. car is stock too.

Thermowax most likely has issue with the high idle. On the back of the throttle body, you would need to set the fast idle cam according to FSM or haynes or etc.
*if im not mistaken*
After the AWS/BAC finishes their 3000rpm start up, the fast idle cam/thermowax takes over, slowly dropping idle from around 1500-1700 to the normal 750 give or take.

That seems weird that it would stay around 2-2.5k for the length of time you said before going to normal. I would say vac. leak, but with that it should never drop back to normal.

Turbo or non? ...Year?

yea that my problem too. but it starts up to 2500 then drops to 2000 then after about 10mis of driving it will drop to 750 give or take. weird.

Nothing to worry about
 

When an engine is cold the combustion within the engine is very poor(Not all the fuel gets burnt) . Infact without the ECU Adjusting the Air / Fuel ratio the engine wouldn't run when cold.

The ECU adds more fuel to counter act this, Therefore the engine runs very rich when cold, this raises the RPM. As the engine warms the ECU gradually adjusts the Air Fuel ratio until it finally settles at the standard running Air/Fuel ratio, when this happens the engine should idle around 750rpm.

Deppending on your driving this time is around 10min. Driving rapidly obviously decreases the time

This happens in all internal combustion engines, but rotaries are very susceptible to poor combustion due to the large combustion surface.

no jus normal shift under 3k, i just drove it at first and relized this time my idle was at 1000-1200. i smell a vac leak...

88 non turbo...yea i thought it was a vac leak too but if it was, it wouldnt drop to 750 rpm once its warmed up....

well if thats the case then i shouldnt be really worried about it but it seems that not all 7's do this....just a few.

I think it is just the thermowax... Believe it or not, when I had an engine fire (pd failure) in my old GXL, the thermowax solidified causing me to have your same issue... When I removed it, it was ok... That is probably your issue.

wheres the thermowax located at? and how do i take if off?

the thermowax, and AWS solenoid are retarded IMHO

Get rid of that stuff... i live in firdgid ND and and love it with out that headache, i jsut have to play with the idle on ice cold start up for a sec and then it is fine

so there just used for keeping the motor running while the motor has poor combustion when cold?

yeah