1991 300zx cuts out at 2500 rpm

[dctobin]

I have a 1991 300zx N/A. 69K miles. When I start it up, it runs fine. then, after running for 10 minutes or so, it starts cutting out completely at 2500 rpm. starts bucking, etc. Sometimes it will get back above 2500 rpm if I rev it out of gear. It also seemed worse when low on fuel, so I installed a new fuel filter, but the bucking/cutting out, while better, still exists.

Any ideas?

Thanks!

[JosefTTZ]

That sounds like a bad MAF (Mass Air Flow Sensor). Check your ECU codes and see if the MAF code comes up. I have also seen no codes even though a MAF was bad. You can also borrow a MAF from someone and swap it, see if that fixes it.

[evildky]

the "bucking" thing kinda sounds liek a failing fuel pump, that and you said it gets worse when low on fuel, the fuel helps to keep the pump body cool, when low on fuel there isn't enough fuel to keep the pump cool, kinda a pita but you might want to get a length of fuel hose an a fuel pressure gauge, and rount it under a wiper arm where you can see it when driving, and see if it drops when the problem occours, I've seen this on S130's but not on Z32's

[300freekzx]

the "bucking" thing kinda sounds liek a failing fuel pump, that and you said it gets worse when low on fuel, the fuel helps to keep the pump body cool, when low on fuel there isn't enough fuel to keep the pump cool, kinda a pita but you might want to get a length of fuel hose an a fuel pressure gauge, and rount it under a wiper arm where you can see it when driving, and see if it drops when the problem occours, I've seen this on S130's but not on Z32's

I will be money it is the coolant temp sensor. I would find some one with a conzult to diagnoss the problem first.

[evildky]

CHTS ususally just floods out and won't restart

[dctobin]

Hey guys --

First, let me say that this forum is fantastic. I had no idea what "check the codes" meant, and went to the how-to section and got instructions to check it.

So, my codes are 12 and 53. I guess I should check the MAF, as originally suggested? Perhaps check the contacts and/or replace.

How about the 53 code? what do I do with a problem with the exhaust gas sensor.

Thanks again -- I really appreciate it.

[evildky]

code 53 is right side O2 sensor

[JosefTTZ]

You probably just need to get a new o2 sensor for the code 53 to go away. You may have also noticed a decrease in gas mileage since the o2 sensor may be malfunctioning.

As for the MAF, that is why you cant go above 2.5K RPMS. The o2 sensor wont cause this.

[dctobin]

Today I pulled the harness on the MAF, then pulled out the MAF. Everything looked fine. I voltage tested connector B on the MAF, and it came back at .03 volts. I understand this is supposed to be at .8-1.5 at idle. I guess I should go ahead an order a new (reman) MAF?

Thanks again for everyone's help.

[dctobin]

Guys --

thank you! after reading your advice, checking codes and voltage, i ordered a replacement MAF. I installed it today, and the car now runs like a top! It sounds great, too. THe MAF code "12" has disappeared as well, leaving only the code 53 for the right side sensor.

So i am going to order a replacement sensor. Now, for a silly question -- i assume the right side sensor is the passenger side? And i understand that one is easier to replace.

Anyway, thank you for all your help. Knowing next to nothing about cars, it is great that I was able to fix this issue with your help.

[jdmshiz]

its how i feel when i have a problem and don't know how to fix it.

[dewdog]

my cousin had the same problem with his vr6. he didnt want to spend the money to fix it so he sold it. the kid that bought it put a new battery in and it worked fine.

[JosefTTZ]

Awesome, usually when Z's dont want to go over 2500RPMs than it is more than likely the MAF.

Glad you fixed it.

[300ZXing]

Does anyone know what would be the best code reader? I have the same problem with my zx.
on my 3rd maf, 2nd tps, and still can not fix.

[nissanfreak12]

Does anyone know what would be the best code reader? I have the same problem with my zx.
on my 3rd maf, 2nd tps, and still can not fix.

The best code reader is already in the ECU or Datascan, but the ECU does well enough. See below.

https://www.google.com/url?sa=t&rct=j&q ... 6858,d.aWM

[z32loverboy]

Nice write up! great info right there!