Hey everyone My 300zx is starting to rev pretty high. It was around the 1.5 mark but now its gone up to 2. it usually stays there for a while. It doesnt do this everytime but its becoming more frequent. Does anyone know why this might be happening? Any help is much appreciated. Its a 91 300zx manual non-turbo, 175000kms. Thanks
I think its the warm up tune. Idle should be ~1200 RPM in cold idle temps under 25 degrees. This droips to the recommended ~700 rpm when operating temp ius reached. What is your idle RPM at operating temp? IE after a 15 minute drive? If its higher than 700 RPM, then your ECU idle control has probably bumped it up
Sometimes when my engine is running at the normal temp it still stays at 2. It doesnt do it all the time though and other times it does drop in revs once its reached operating temp. but yea, not every time.
Check the coolant temp sensor (front of engine, left plug) clean contacts. If the ECU can't read the temp it will assume its cold and thus raise the idle. Is the AUX fan running? If so the temp sensor isn't functioning. After that check the IACV connections. Back of engine drivers side. After that check the Idle control valve, back of engine in the middle. Flick the Air con off and on and see if the revs rise when off. Other than that it might be a small boost leak and the IACV is copensating and rasing the Idle. Beavis
