Idle is very high please help

[Laser_Run209]

hey i have a 1990 plymouth laser rs turbo. i have a idleing problem. when i start the car the idle stays a 3000 rpm to 3500 rpm when its on neutral or when im holding the clutch down. someone please help me.

 

[jwahl425]

is your check engine light on? if so you could check the signal pulses, other wise is your ISC motor (idle speed control) installed correctly/poss. broke? do you have the correct ECU? what all have you eliminated from the possible causes?

 

[Laser_Run209]

no engine light comes on. its not the throttle cable cuz i already tried it. i took that screw out which even it more higher in rpm so i put it back. could i just change throttle bodies and would it eliminate the problem of high as rpm. and i think its making my clutch wear alot because i leave it in gear when its a red light and i let go of the clutch alittle bit and stepping on the brakes so the rpm would at least stay at 2000 rpm.

 

[jwahl425]

not sure about swapping TB, it's normally better if you diagnos the problem before you buy the parts,like I said, it could isc motor is bad, they normally are, but then wouldn't it run lower rpm's instead of higher? huh, ECu is a poss. but I'm not 100%, you can start the car and try to rotate the thing that the TB wire goes to (can't remember what it's calle) try to rotate it clockwise if you are facing it from front. if the rpm's go down then you need to adjust TB, if they stay you may have a bad ISC or ECU. That's y 2 cents, I'm no DSM Wiseman