My 1991 300zx TT Jap import is running at 1500rpm at idle and was thinking it might be a cam belt problem and since i have only purchased the car decided to change it anyway. The car was an Auto converted to manual. What would cause it to run at such high revs. Some lad messed with the the timing to try and sort it but made it worse. afraid to drive it now in case it wrecks my engine.

sounds like the tps has been moved.

you may need to set it back to 0.45v with a volt meter takes 5 minutes.

then you may have to adjust the idle by using the idle screw.

there is a sticky somewhere on this procedure.

 

 

if none of this works then id suspect an air leak or dodgy idle valve. or maybe a jammed air regulator but not sure if they are common for failing.

Has the neutral switch been connected ?

 

http://www.300zx.co.uk/forums/showthread.php?t=63335&referrerid=4456

Edited July 24, 200817 yr by Jeremy

if the neutral switch isn't connected it will idle at 25 degrees timing rather than 15 degrees causing high idle, you can just earth pin 44 at the ecu if you want but connecting the neutral switch is the proper way to do it

My 1991 300zx TT Jap import is running at 1500rpm at idle and was thinking it might be a cam belt problem and since i have only purchased the car decided to change it anyway. The car was an Auto converted to manual. What would cause it to run at such high revs. Some lad messed with the the timing to try and sort it but made it worse. afraid to drive it now in case it wrecks my engine.

 

Chewies old car?

 

Sounds like the neutral switch to me... mine does exactly the same :) Idles a bit high because of the timing is at 25* instead of 15.

messing with the idle valve should be the last resort after ALL other peramameters have been checked first;)

Edited July 24, 200817 yr by znut

messing with the idle valve should be the last resort after ALL other perimeters have been checked first;)

 

true.

ok timing belt should be finished tomorrow and then i will check the neutral switch. Thanks guys. Yep its chewies old car and is a credit to him as he has spent alot of time and effort on it so i am only tryin to iron out the finer details to get her runnin sweet like i had my old TT.

Not sure if i sound like a dope but where is the neutral switch. It said above that it is where the gear lever is and has to be held in the in position with a tie wrap. Does anyone have any pics of this as i am not big into wiring things and would more than likely make a balls of it. Thanks again guys.

http://www.300zx.co.uk/forums/attachment.php?attachmentid=34524&d=1181659320