having probs with 84 300zx cant figure out

[anensen]

ive replaced my o2, mass airflow, plugs, rotor, wires, cap, air filter, injectors, injector plugs, ecu, pcv valve, distributer(used). My car is running irradic, rough idle, sluggish, and sometimes it will not idle at all or start to backfire and not rev at all. if i get the rpm's up it will stay alive but as soon as i let the rpm's below 2800 it doesn't want to rev back up at all. when its cold it doesn't want to run at all i have to start it about 30 times. once its warmed up it runs iffy for 10 to 15 min then it starts acting up

[evildky]

vac leak, clogged, non functioning AIV?

I'm sure AZ_ZBum can offer more

[Pharaohabq]

Have you tried a reset on the computer after replacing all those items, incl MAF? Mine was running like crap when the MAF died, and kept running badly until I reset the computer. this got it out of "limp" mode and back to running normally. The comp should normally figure things out after idling a while though.

[AZ-ZBum]

Have you tried a reset on the computer after replacing all those items, incl MAF? Mine was running like crap when the MAF died, and kept running badly until I reset the computer. this got it out of "limp" mode and back to running normally. The comp should normally figure things out after idling a while though.

And what is resetting the ECU going to do? Oh yeah. NOTHING! It will delete the error codes, but it will not affect the running condition. The Z31's ECU is NOT a learning ECU. It gets it's signals from the various sensors and adjusts accordingly.

anensen: Have you done a compression test? Have you done a fuel pressure test? Have you read the codes from the ECU? I would suspect a faulty fuel pressure regulator, bad ECU, or bad coil or power transistor. Bad FPR would be first.

[XJared]

check fuel pressure, if that's ok, clean the injectors and replace the headtemp sensor and sub harness.

[BadQ45t]

Does it get any better when it is warm? The cylinder head temp sensors in these cars only last 100k at most, my 84' is on its 3rd one (I have 160k original miles). You might also have a BAD ECU, but I agree unplugging or resetting it will probably not do a whole lot.

Find youself a good Nissan aftermarket mechanic, these older Z31s are not that complicated, I know my mechanic that has worked on my Z for 15 years can fix anything on it...your car sounds like your freshened nearly everything so your just missing something.