Idle problem...

[omgdudewtf]

I picked up a 93' SE fastback a while ago, and I'm just now getting around to it. KA24DE, auto trans. Starting the car takes about 5-10 trys before it finally turns over, this could be just from sitting so long. I then have to keep the rpms up because the car will not idle by itself... if I hold it to 2000 rpms and let off, it will slowly drop to 1000, then 500, then begin to die like its starving for air or fuel. I held the idle at 2000 rpms for about 10-15 minutes until the car warmed up, and it idled steady and smooth but remained 2000, responded well to a punch of the throttle... rpms came back down and idle went right back up to 2000 rpms.

Whats the first thing I should check? I thought maybey a TPS because if it didnt know what to idle at, holding it at 2000 rpms for that long possibly could have made a new map or somthing to follow, being the reason it idles smooth at 2000.

Possible problems I've come up with, but do not know how to go about fixing are: TPS (thought it would have thrown a CEL if it wasn't reading correctly), IACV (heard they need cleaned, previous owner claims they cleaned it.. I'm leaning on this one), vacum leak (looked for disconnect hose, but didn't really find any hoses easily visible). Previous owner claims it was way out of time, but it sure as hell doesn't act like it. Once it warms up the car idles normally and responds to throttle position just fine.

Any ideas??

[180fan]

I'd check the iacv. cleaning won't fix a bad iacv. but if it's limiting to 2k, you may want to look at the mafs with a suspicious eye.

[omgdudewtf]

Its not limiting to 2000rpms, it just idles there. I took it to 4000 with no problem, but I didn't take it higher than that because the car hasnt been started in a long while.

[roadrace240]

i have the same problem on my single cam motor exact same symptomstakes a while to start, then when it does it sputers a bit a round 500 bump the gas and and it will go to 2000 smoothly and stay there, runs fine any where above idle until it gets warm and then it idles fine

i called nissan and the guy said difenitly the o2 sensorso i got new one and it acted alitle different but still had some what the same problem

i changed the temp sensor (the small one for the gage which makes no since to me at all) and the problem seemed to have vanished

hope this helps!
Modified by roadrace240 at 6:52 PM 4/15/2006