tuckphyler wrote:Alright so I've had this issue for a while now and I've done tons of research and haven't found anything that solved my problem, which is why I am now posting about it here.
Most cars will idle a tad bit high when they start up, and idle normally once they warm up. But my car seems to idle high at all times. I will start by saying that this issue seems to be mostly/only present in the winter in cold temperatures. When I start my car it revs up to about 2.5-3k rpm, and then maybe drop a bit. Stays like that until the car is warmed up, and then when it is it idles between 1.5-2.5k rpm (varies on how cold it is outside) while driving. So anytime i'm driving and throw it in neutral it jump up to around that range until i start to let off the clutch to go into gear. Does anyone have any idea what this could be about? Also it seems to possibly have worsened my gas mileage obviously since it's burning more gas with it revving so high, but there's smell of gas fumes around my car often? I came seeking advice from the experts here before I take it to Nissan to drop a high bill to have them diagnose it. Yes i have adjusted my iacv, and yes I've tested for a vacuum leak and there didn't appear to be an unusual amount of psi (though just for reference if someone could tell me the stock psi it is supposed to be at just for double checking). I'm at a brick wall here guys so any advice would be appreciated.
There's a whole bunch of things it could be honestly, but most likely it's either a vacuum leak, bad/stuck IACV, uncalibrated throttle position sensor, or the throttle bodies themselves are not adjusted right.
The only good way to test for vacuum leaks is to use (or make) one of these:
Boost leak tester
Your pressurize with an air compressor to like ~10psi and listen for leaks.
Here's the writeup on how to check the IACV:
iacv-aac-cleaning-and-testing-tutorial-t251133.html
And the TPS sensor:
http://www.twinturbo.net/nissan/300zx/f ... ensor.html
I doubt your throttle bodies are out of adjustment, but it is possible. There are little screws that you can turn to adjust how open/closed the TB's are:
http://www.twinturbo.net/nissan/300zx/f ... izing.html
I've had high idle problems before too, but not nearly as high as you guys. When warm and in gear mine would sit at ~1000 or so rpms. When I put my IACV back together after doing a plenum pull I must have not put it back together right and it was causing problems. The fuel you are smelling is probably because the air/fuel ratio is all jacked up and you're running really rich leading to unburnt gas in the exhaust. If it's cold out where you live, you should really check all of your fuel line clamps to make sure they are tight. They are notorious for leaking when it gets cold out.
