Idle problem

[InsanityInc]

Well, my 1991 240SX SE idles oddly.

You'll pull up to a stop, and if you're only there a few seconds, it'll be fine. However, if you stay any longer, you'll start to notice that the engine bogs a little, you can feel the whole car shake a little and hear the engine slow down. This is also accompanied by a drop in the idle, then the idle comes back up.

The longer you stay stopped, the more frequent, and more noticable it gets, until you can pretty visibly see the entire car jerk every few seconds.

I've replaced just about everything on the car. However, it might have something to do with the TPS. My FSM says to test the resistance across terminals 1 and 2, and when I do, my readings are completely backwards of what the FSM says they should be. But if I hook it up to terminals 2 and 3, I can set the TPS to the resistance it's supposed to be at idle according to the FSM (if I was measuring across 1 and 2), but the car still has the same idle problems.

The car also has a problem starting, and the RPMs drop under electrical load, so it could be related to one of those things.

If anyone has any ideas, and can tell me a better way to adjust the TPS correctly, I'm all ears.

[InsanityInc]

one thing i have to wonder... I have an exhaust leak coming from where my PAIR valve connects to my header, could the escaping exhaust be recirculating into the intake and be causing the rough idle? I have a cone filter, so it's sucking in the under hood air.
Modified by InsanityInc at 5:00 AM 9/18/2004

[navysnail]

how much exhaust are we talking about, it would have to be alot

[InsanityInc]

well, it's not a whole lot, but the idle problem also isn't that severe, it's just obviously noticable.