stephenspann27
NAXJA Forum User
- Location
- College Station, Tx
My '87 XJ 4.0 AW4 has had an erratic idle since I got it.. it will basically idle down really low.. to the point where the motor is misfiring, then idle back up to 'normal' RPM. (I dont' have a tac) So far.. from my parts jeep, I've swaped, IAC, Air temp, MAP, and throttle body (with different TPS). The only thing that made a difference was the throttle body. When I cranked it up, it idled evenly, but too high.. I'm guessing about 1200 RPM. I looked at the # of threads showing on the throttle stop screw, and compared it to the old throttle body. The throttle body I had just installed had the stop cranked out quite a bit more. I slowing cranked the stop back in, and left the idle set a bit higher than it had been with the old throttle body.
Now that I have the idle set a bit higher.. I'd guess 800rpm.. you can't tell as much that the idle is erratic.. because when it idles down "low" it isn't low enough to cause it to misfire. I was wondering if.. the ECU is sensitive to the idle RPM and will try to adjust fuel and spark to achieve it? I'll try to buy an aftermarket tac and install it..
One other thing.. before I had started driving the jeep regularly, when the jeep would sit.. for a month or two, the first 20 miles or so it would misfire.. then the misfire would disappear.. That behavior is making me thinking that maybe I have a sticky injector? (I've tried cleaner). I have the whole fuel rail, from my parts jeep, with the injectors and regulator still on it..I was thinking of swapping it over to see if it would fix the problem....
thoughts?
Now that I have the idle set a bit higher.. I'd guess 800rpm.. you can't tell as much that the idle is erratic.. because when it idles down "low" it isn't low enough to cause it to misfire. I was wondering if.. the ECU is sensitive to the idle RPM and will try to adjust fuel and spark to achieve it? I'll try to buy an aftermarket tac and install it..
One other thing.. before I had started driving the jeep regularly, when the jeep would sit.. for a month or two, the first 20 miles or so it would misfire.. then the misfire would disappear.. That behavior is making me thinking that maybe I have a sticky injector? (I've tried cleaner). I have the whole fuel rail, from my parts jeep, with the injectors and regulator still on it..I was thinking of swapping it over to see if it would fix the problem....
thoughts?