300zx help

[nissanz300]

alright i have a 91 nissan 300zx. its been giving me some trouble. one the idle is off. it pulses low. real low like it wants to die. and sometimes it idles a little high at like 1100 or maybe even 1200. not only that it seems very hesitant when i shift gears. it seems like i lost power and its not as fast, it feels like it msses sometimes on acceleration. also it bucks. bad at times. like im hitting the gas on and off real fast. i just replaced the coolant temp sensor so thats good. im thinking it might be the maf sensor. someone please help. would be appreciated.

[Hijacker]

It sounds like a bad TPS to me.

[nissanz300]

how do i tell if its bad or not?

[Hijacker]

Unplug it and take it on a test drive. The ECU should have a default mapping for running without it, so you should lose the stuttering. The car still won't run right, but it should run better than it is now. Also, the idle should stabilize.

If the car seems to idle better with the TPS unplugged, either the unit needs to be replaced, or you need to test it to make sure the voltage readings are accurate.

Here's a good guide on how to test the TPS for correct voltage.http://www.primera-egt.com/pri...t.htm

It's for a Primera, but the methodology is the same for all Nissans of the era.

[driftingmy240sx]

sounds like all the signs of a bad maf. i have rarely seen a bad tps on nissans, normally when they go bad its from someone messing wth them. however i would not completely rule out a tps, but beleive the maf is ore likely the cause.is the check engine light on?

[NISTECH]

since your were messing with the harness on the front of the engine I would suspect you disturbed the connections at the trig unit or the cam sensor. Those connectors tend to corrode real bad inside and cause all kinds of run problems.

[nissanz300]

no there is no check engine light. also i ran the self test and nothing. also i replaced the coolant temp sensor after it started doing this. i checked the mas and it would sit at a steady reading and as i reved it up it would slowly rise. i was told that means its good. well it did something new today. i left work and as i started to drive out of the parking lot it started to cut in and out and wouldnt go past 2500revs. if i press the gas slowly it would cut in and out faster and as i press the pedal in further it would cut in and out harder but slower. then i decided to try to get it home and on the way home i decided to try and go past 2500 and see what happened. well it started to work normal. i wonder if its something during warm up. no clue. ill check the tps and update you. unlss there are more ideas

[nissanz300]

alright just checked the tps. i had zero volts at idle. and no matter if i barely touched the throttle, snap it, slowly increase, or wot it would read 12.38(battery voltage). im pretty sure this means its bad right? also i noticed some corrosion on the connectors. cleaned it just enough for the test though.

[nissanz300]

well i put a new tps on it. and still. but i definetly noticed a pattern. when i first start driving for a couple minutes the car is fine. then all of a sudden it starts. i have to push the gas in real slow or it will start to buck. cant go past 2000-2500 rpms not matter what. i even down shifted so the revs were at like 3500 and i tried to give it gas. nothing.....the revs kept going down like i didnt even try to press the pedal. then like before after a few minutes of taking it easy and slow it will start to work normal again. and pretty much stay like that for the rest of the night. wierd.

[Hijacker]

When the car won't go past 2500 rpms, the maf is the culprit. The ECU enters what's known as limp mode and won't let the car rev past 2500. Also, the car will tend to buck as well during limp mode. given that your symptoms seem to come and go, I would suggest removing the MAF, check the plug for corrosion and then clean the heating element in the MAF with a cleaner. You can pick up cleaners designed for MAFs at a local auto store.