need some help fixing my friend's car...tech guys help me out.
 

Car:

1993 Nissan Quest
180K Miles
3.0 V6

Problem:

After the engine warms up, it won't rev past around 2000-2500 rpm. The car will jerk and sputter at that point and will only return to normal after the car has been shut off and cooled down.

Help me out, guys. I'm hoping you guys in here will know since it's a Nissan of the same era as your guys' Maximas.

maf failure.

Maxima ECU uses MAF, TPS, Tachometer to ctrl the engine during six minute warmup. If one of those sensors fail, ECU drops to 2000rpm limit safe mode (not in your case).

After warmup period, O2 (&temp) sensor is added to the ctrl loop. If one fails, ECU drops to 2000rpm limit safe mode ... your case.

My guess would be O2 sensor or Temp sensor?

don't guess around, check ECU. if it's tripping safe mode every time and not intermittently the ECU prolly knows what's wrong.

ECU=lottery machine with 50 answerss to 5000 problems...

WTF, c'mon dude don't disrespect the forum "Nissan Quest"


Like Jeff said its most probably the MAFS.

maf is the only sensor that when it fails limits to 2500rpms

is there any way to know if the MAF on there currently is definitely bad? any way to test it? clean it? also, where exactly is it? i haven't seen my friend's car in a while so i just want to know exactly where to look. i'm guessing somewhere along the intake tube/throttle body area?

any other suggestions? thanks so much, guys.

I have collected the sensor tst -how to- list on my web page. Link has been available, will u read?:
http://www.cardomain.com/memberpage/748507/9
Use it with the crap online manual, available via autozone.com


subs1000w --->"maf is the only sensor that when it fails limits to 2500rpms"
Not so. And that is Easy to tst...

disconnect the maf and see if the symptoms change

car's max rpm varies between 2000-3000 ish. does that mean it's not the MAF? the MAF problem exists when the max RPM is 2200 rpm, correct?

so if it's not a MAF malfunction, what could it be?

When you disconnect the MAF, the engine will not rev higher than 2200 RPM.
So, if you cant rev the engine past 2200 RPM with the MAP connected, you probably have a bad MAF......I would also check the resistance of it also..
Click on internetautopar SAE logo for prices of a new or reman MAF

remember guys this a quest not a maxima, so it's limp home mode may be different than ours.
I stick by my suggestion to unplug the maf and see if the symptoms change.

Quite a lot variables there. U have to eliminate one by one via checking...

Fuel: pressure, ignition: transistor/capacitor (if cap, replace with wires, plugs), all air flow variables: from filter to loose TB flaps, sensors: all 'ten' from tacho to O2.

--->Go find FSmanual. Inspect those probabilities mentioned in this chain. Then come back and tell about u results....