Thread: High idle

What the hell is wrong with my 98 SE-R SR20DE? Lately the engine has been idling really high, like 1500 rpm. Sometimes higher. This is when the car is already warm/been driven for 20 miles or so. When I unplug the tps it goes down to normal. I read somewhere that it could be my aac valve? I'm stumped, again. Help guys.

Just went out to start the car and it is idling normal at 800 rpms. Checked for codes and got nothing. Car isn't over heating either. This sounds like it's going to be a pain in the ass to diagnose.

I now have a code P0443 Evap Emission Control System Purge Control Valve Circuit. WTF is this and where is it located? Could a bad gas cap cause this code? I just checked my gas cap and it was loose and it didn't release any pressure when I removed it. I replaced this cap about 2 years ago, maybe 3 years. I also noticed just now that the engine was "hunting" a little. It would be awesome if it was just a bad gas cap. It is a Nissan gas cap, bought it at the dealer for like $18 bucks if I remember correctly.

Did you recently mess with or clean your throttle body?

You know what? About a month ago this happened for the first time, that time I did clean the throttle body. I also put some seafoam in the gas tank. Just 2 days ago I cleaned the throttle body again, I did this hoping that it would fix the problem. Like I said before my gas cap was loose, so maybe this has something to do with it? I also noticed the rubber gasket on the cap was wet with gas? Maybe it worked it's way loose because of that? Shit I don't know what's going on.

Not clear from your post whether the fast idle came before or after you cleaned the throttle body. If after, then consider this.

When you clean the TB you basically increase the amount of air entering the engine at idle. Most times you need to adjust the base idle to compensate for this physical change in the air flow. (As the crud in the TB slowly builds up over time, the ECU learns to compensate by lowering air flow through the idle adjust valve.) Now that you've removed the crud, the ECU is confused. As I said, you can help it out by setting the base idle. Search on the forums for detailed instructions -- don't just go cranking on idle or throttle adjust screws.

The other thing it might be is a vacuum leak from one of the many vacuum hoses.

This first happened last month when I cleaned the throttle body. It had a high idle, then it went back to normal. Fast forward to 3 days ago, it happened again. Only this time I didn't even clean the throttle body. Anyway the high idle went away for awhile yesterday. Then it came back again .

Yesterday I went to Best Buy. That was a 20 mile round trip. No idle problems, then when I get home to my driveway it started again with the high idle. Weird stuff man. Weird stuff.

My car is still doing this. It's an intermittent thing now. I checked for codes again and this time I got nothing.

Could be car is increasing RPM when fans come on? I'm having a similar mystery. Although it only does it for me when I have the headlights off. When headlights are on, RPM stays around 1k or less.

BTW, did you set your base idle?? What position is the idle adjuster screw at? Mine is all the way down(low).

-G

My VE used to do this. If you shut the car off then turn it back on before the motor dies out it would revv higher.. well mine would.

Took my IACV off and it was blacker than night inside. I used an entire can of TB cleaner to clean it out and ever since then I've been okay.