rev hang help

[lancermat]

Just bought a 240sx with the ka24 in it. I know its supposed to idle high when its cold. However after its warm it idles at 750-800 until i gently blip the gas then it will hang at 1500rpm and take a few seconds to come down? What is wrong with it? I suspect that the oil from the K&n drop in filter could have messed with the maf??? Any ideas thanks.

[Jmoore124]

Very unlikely that your MAF has anything to do with it. You can take it out and clean it with some MAF cleaner if you want. Check and make sure your throttle body is closing all the way with someone else working the gas pedal. Make sure the pedal itself does not stick in this condition. If its not that, it may be related to your IACV or a vacuum issue.

[mechanicalmoron]

Mine does that, to a degree.

If you come off the gas in neutral, it drops and slows as it gets to 1500, but won't hang. If you blip it to 1500, it hangs for a second.

I assumed it was just the time it took for the vaccum in the manifold to raise again.

TPS and IACV setting do affect it a bit, IME.

But if it's running well, I wouldn't worry about it, it's not like you're going to be shifting from 1500 to 700 RPM, and need a fast drop there.

You could check your codes, maybe something like a leaky injector could make it worse.

[JGT Customs]

I had a similar issue on my vehicle, but you could feel the throttle sticking closed at times too. You'd have to hit the gas harder than you should in order to get it to actually release or open the throttle. I cleaned the idle air valve and also lubed up the spring area on my throttle body. The throttle is now very smooth and the idle drops like it's supposed to. Not sure which fixed it, but I think it was a combo of the two