Need help! Engine runs rough

[MDR300zx]

I have a 1994 Z 2+2 with 164k. It has started to run rough. If you give it fuel slowly it revs up fine but as soon as you give it to much throttle it falls on it face. I changed the fuel filter and its not throwing any codes. When the car has sat over night it runs fine for a few minutes and then starts doing the same thing as soon as it warms. I checked all the coils to see if they were firing and they were. Any ideas?
Thanks in advance.

[DeeZX]

Have you checked the injectors? Are there any vacuum leaks? What about your alternator, is the charging voltage correct 13.6V + 0r - 0.3V?

[evildky]

check th eecu fo codes, most likely an afm or tps issue, search this has cme up a few times now

[dantesdoom]

my car had the same problem...ohm fuel injectors...replace if necessary...i also cleaned the TBs. My problem cleared right up after this.

[MDR300zx]

Ok i cleaned the TB and ohmed the injectors, all read 12 except #4 read 15 to 16 is that the bad one?

[evildky]

clean the contacts ont he high reading injectors and retest, standard should be 12-14 ohms

[MDR300zx]

There clean. Im getting ready to pull the plenum, any tips or things i should know?
Thanks

[evildky]

1-2 ohms high is generally not enought o worry about, you said your idle si fine, if your idle is fine then the injectors are fine, if the idle is bad ont those 2 cylinders then have at

[MDR300zx]

well i replaced the injector and it runs worse lol. It idles fine but will not rev up or when it does its slow in doing it. This is driving me crazy! What do i need to do next?

[jas_mathews]

Have you checked your timing? I have found conflicting info on this but from the Nissan repair manual it says for N/A engines it should be 10 degrees +/-2 and for tt models it should be 15 degrees +/-2. I just adjusted mine from 15 to 10 and it seemed to work for the constant engine lope i was experiencing at idle when the engine was warm but now I feel like the engine is lagging until it reaches 3000 + rpm. If I am at a complete stop and hit it hard it takes off powerfully, but if I am already moving it just bogs. Has Any body else experienced this?

[MDR300zx]

Im sure its not the timing because it was running fine and started to hesitate and now it will hardly even rev up. Im still at a loss with this thing. Glad its not my DD.

[DeeZX]

Don't know if you found your problem yet. but I think it might be your Crank Angle Sensor (CAS). The dowel that keeps it in position could be worn down or miss shaped and its shaky.
Another possibility could be a corroded fuse, in particular, the 10 amp fuse labeled ECU in your under hood fuse box. This recently happen to me. Before I found this, my Z displayed similar symptoms.

[MDR300zx]

No i have not figured it out yet. I will check the fuse first.

[es.biggs]

If you live around anyone with a Z32, you could try swapping your CAS with a known good one. Also make sure your TPS is adjusted properly. Specs are in the service manual - there is one online here: http://www.300zx-twinturbo.com/cgi-bin/manual.cgi