ok. i already posted this but i have more details with my problem. i have a 1989 240sx with a ka24e. 118 000km on it. when i start it up everything is running perfectly fine. idle is a bit high, around 1600rpm. once the car is about at running temperature my idle starts to go crazy. revs up to about 2000rpm then drops back down to 1600rpm. creeps back up and drops. it does this about every 2 seconds. i checked my vacuum lines and replaced one that had a crack at the end. i pulled off my idle air control valve and it wasnt all that gunked up with carbon. bit i still cleaned it with some intake cleaner. still have the problem. seen if it was a coolant bubble like others said in the other post. nope not it. so any ideas. i asked my auto teacher and he said theres a possibility its an o2 sensor. so could it be an o2 sensor?
i havnt done any real driving because its not insured. but i have taken it around my shop that i work at a couple of times and it doesnt seem to be doing it when driving. and when it is just sitting there if i give it some gas it will drop down and it wont start fluctuating for a couple seconds.
Don’t listen to the above until you bleed your coolant system. It sounds like you have a bubble. To burp it, jack it up to approx 30 degrees in the air from the front, pop off the rad cap, and leave it running till you see all of the air bubbles escape. If you need more indepth info, please feel free to PM.
Coop LE, you are wrong. A fluctuating idle CAN be caused by a coolant bubble - the IACV wont recieve the proper amount of coolant. There are two small coolant lines runnign right do it, underneath the intake manifolt - they T off of the large coolant line going alongside the block. Try it man, what do you have to lose? Use a process of elimination instead of going and blowing a tonne of cash on all the sensors that are likely fine.
well wen i pulled off my iacv there was no coolant. my shop even said that it doesnt run off coolant. now today i unplugged my tps and bam idles at 750rmp and not fluctuating. i plug it back in and its still at 750rpm and not fluctuating so i think i found it. and that was at 3 befor i went to work. now after work i checked it again but this time its a high idle but not fluctuating. so is it a tps?
