I've this car for about weak, and it idles hard, hard enough to be shaking the shifter around and the car a little bit. It idles about 750-850 rpm and will jump to like 1050 every now and then, I think just to turn the AC back on (you know how nissans will auto shut off AC to cool down for like 20 seconds at idle then kick it back on?)....Could this be due to dirty injectors? Or too advanced/retarded timing? I picked up a bottle of STP fuel system cleaner today, just waiting to fill it up to add it, should I maybe jsut do that and go through the tank and see what happens?
P.S. It's an 89 240sx hatchback with the original KAE, 200k miles on it. I'm sure you could have gathered from the sig but better safe then flamed.
HARD idle
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Nismo_Freak
- Posts: 10314
- Joined: Wed Jul 24, 2002 10:42 pm
- Car: 89 Nissan 240SX
I think what you are feeling is the typical old big 4 cyl. shake. Large 4 cyl. motors always have shaken at idle, and when paired with old engine mounts you can get some feedback in the car. The QR25DE motor doesn't have this shake because of it's balancing system that Nissan installed somewhat for the purpose of eliminating the shake.
only thing that comes to mind by discription is it is hunting. which could be caused by vaccum leak, injector lossing ground(wich isnt uncommon on the 24e) or unmetered air after the air flow meter. if its the injector ground try moving the harness around by the valve cover near the rear. see if it affects the condition
ok, so i added some fuel system cleaner, and it seems a little better, but it sounds like it may be what you are talking about, it moves around like it is hunting at idle, and i kept it steady at 2k rpms, did the same thing there. Also at idle, with the AC on, it will stay at 1000rpm for about a minute, then die down to 750rpm and seem like it's going to stall out, although it never has, so i just rev it and it repeats the process. Any ideas?