1991 ka24de s13 idle problems, help!

[boycelaforest707]

Ok here is the situation, my car idles at about 700 rpm typically (roughly), if you are slowing down in gear and press the clutch in, it drops to 400-500 almost stalls then comes back up to 700. Sitting there at 700, if I turn A/C on it goes up to 1000.I have replaced the fuel filter and fuel pump ($120) OUCH! And solved nothing. No codes from computer either. Already searched through forums, wondering if somebody had this exact problem and how it was fixed, from my search, I could replace the O2/TPS/MAF/IAC and tons of other stuff, is there a way to narrow this down?

[bruinbear714]

Ok here is the situation, my car idles at about 700 rpm typically (roughly), if you are slowing down in gear and press the clutch in, it drops to 400-500 almost stalls then comes back up to 700. Sitting there at 700, if I turn A/C on it goes up to 1000.I have replaced the fuel filter and fuel pump ($120) OUCH! And solved nothing. No codes from computer either. Already searched through forums, wondering if somebody had this exact problem and how it was fixed, from my search, I could replace the O2/TPS/MAF/IAC and tons of other stuff, is there a way to narrow this down?

It could be a lot of things....

1) Vacuum leak after your MAF - you can verify by getting a multimeter and probing your friend's working car, read out the voltage, and then probe your car.

2) Fuel problem - too rich, or lean?

3) Bad timing?

4) Clogged fuel filter?

5) Clogged injectors?

Start with the quick and easy checks first - 1 and 3. Then try replacing your fuel filter.

[tiger]

my friend had a supra that did that... it wouldn't idle unless he had the AC turned on... i told him to replace his belts... i dont remember why but after he did he said the problem went away

[TheOne]

could be the IAA, AAC, and all the idle control systems, could also be the AIV since you have an S13. here, 2 things to check for, also check your grounds.(mine was having that same problem, it was because the ground that goes after all the fuel injector harness finishes, it grounds to the head, it was loose a bit cause it was cut out of the harness long time ago so it was causing it to stall, got that fixed and it idles good now)

zerothread?id=26150

zerothread?id=26039

[boycelaforest707]

Ok replaced the spark plug wires, it idles better but still has a rough idle.

[petesleaf]

Try replacing the Oxygen sensor. It has a lot to do with everything and controls what the ECU decides on the the fuel mixture. It is recommended to be replaced every 30k. Also check the small hose on the bottom of the BPT valve next to the EGR valve at the rear of the engine for deterioration/leaking. They all melt because of the heat given off from the exhaust gas heat pipe leading from the exhaust mainfold to the EGR valve. Every 92 Ive checked had a melted hose on the bottom.

[sparkplugs.com]

denso #234-1013 or ngk#23044