Climbing idle, how to fix?

[elvis240sx]

Yes i searched around but didnt find anything on how to fix my problem. Its a soch hatchback 240. When i bought my car about a year ago, the idle was really high, about 2k rpms. a few months ago i turned the idle down to like 900-1000k rpms. its ran really well for a while with no problems. Now, it seems to be acting funny. When i first start the car it will idle at like 1500rpms, then drop down to where i set the idle. after driving for a minute, if i stop at a redlight or stop sign, it will occasionally rise up to an idle of like 2100rpms and stay there. if i tap the gas, it will go back down, but sometimes climb up again. Im not sure what i should do in order to fix this.

not sure if this also has anything to do with the problem, but ill ad dit anyway. a few months ago, the car would bog out really bad if i stepped on it at all. but, if i just barely, and i mean barely feathered the gas, it would go without shaking or jerking, but of course really slowly. it was like i had to give ti just enough gas to take off without stalling. so, i took it in to one of the mechanics my dad works with, and he really couldnt find anything wrong with it, except for the timing being a little bit off, so he fixed that. 2 weeks later, it started happening again. this time, it was the alternator, so i put a new one on and the car seemed fine. now, the car will kind of bog out and seem gutless if i dont give it about half gas. at full throttle it seems choked out or weak, and it also feels that way at anything less than half throttle.

i have gone through almost all of the wiring connections and cleaned them with a wire brush and reconnected. i just replaced the 02 sensor 2 months ago, and fuel pump about 6 months ago.

BTW, when i first turned down the idle, im pretty sure i did it correctly, but maybe i didnt. there was a flathead screw on the passenger side of the plenum, so i turned it until the idle went down to where i wanted it to be. did i do this incorrectly?

if anyone can help, it is very much appreciated

[elvis240sx]

ok, i searched around more and found a thread about the throttle position sensor. it said that if you unhook the tps, the idle should drop a little and if it doesnt, the sensor is broken. there are two sets of wires going to this. one of them hooks right onto the sensor itself and is held on by a little metal ring clip type thing. the other is like a bulky plastic wire harness that hangs off the top of the sensor, and clips to another harness. when i unhook the two harnesses, my idle climbs from 1000rpms to like 1700rpms for like 3 seconds, then goes back down. if i unhook the metal clip and pull off the other set of wires, nothing really happens. does this mean anything? lol

[Nismo_Freak]

Sounds like your car is an automatic, which would make the other connector the WOT (Wide Open Throttle) switch. At idle the switch won't do anything.

Before you go replacing your TPS you need to check it. I personally don't think it's your TPS, but it is a possibility.

If you want to check your TPS signal do the following:

- Start Motor (allow to warm up, and let it idle) - Disconnect the electrical harness from the TPS- Check for resistance between the pins on the sensor

Specifications:

96-98 Model Years Idle - ~0.5 kilohmPartial Throttle - 0.5 - 4.0 kilohmsWOT - ~4.0 kilohms

95 Model YearIdle - ~1.0 kilohm Partial Throttle - 1.0 - 10.0 kilohmsWOT - ~10.0 kilohms

93-94 Model YearsIdle - ~2.0 kilohmsPartial Throttle - 2.0 - 10.0 kilohmsWOT - ~10.0 kilohms

* Steadily open the throttle and watch for spikes or drops in resistance. It should be a steady linear rise in resistance. If you find any spikes or drops then you need a new TPS.

Granted the SOHC model's aren't on the list, you can go look them up in your service manual or try calling your local Nissan tech about it. Just go search for it, if you can't find it by Monday lemme know and I'll look it up at work.

[elvis240sx]

my car is 5speed, but i will try what you have mentioned and see if anything is wrong with it. i dont tihnk it is the problem either, but i saw it mentioned in a thread about idle problems or power loss, so i figured it was worth a shot