90 na z miss randomly

[dsmjlo]

ok so i just got this car for a steal... lol um it has a random miss fire comes and goes i cant pin point if its at the same time or wat. before i go mental figuring this out is there any well know problem i can check for. other question is there a vin on the motor anywere. the dude i got it off of says the motor was replaced in 02 ........ i was told the 90 model had problem with the head ? id appricate any help or advice thanks ahead of time!

[Sileighty_85]

there were a few issues with the early 300zx, main one is probably the Injectors.
Nissan wired it to where the injectors had power 24/7 which ended up killing injectors over time.

forgot about the others though, Im if you google 300ZX common issues you will find out

[joesmith]

common misfire are caused by spark plugs...
check plugs and make sure it's gapped properly.

[sl0th]

could misfire also be caused by slightly off timing???

[Supergoji]

yes that could also be the case.

this website has a wealth of info that every Z32 owner should know.
http://www.ttxtz.com/tech.html


run your codes and do this.

the 6 P's: proper preparation prevents piss poor performance (http://www.twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=922678)

[mnmax]

i also have a 90 n/a z... when i first got it, it had the same issues. just like sileighty said, my problem was with the injectors. it would be intermittent at times then all of a sudden stop working. my suggestion would be to swap to the later style injectors and upgrade your ignition system if in your budget.

[Alexlua]

Did you ohm out the injectors? try doing that first,

On early Z's the harness isn't all that great. They decided not to put "gaskets" ( a tiny piece of rubber around the edge of the plugs inside) 94+ Z's ave them as wel as the new efi harnesses, anyway no gaskets in the connectors lets moisture in and corrodes the connectors causing a bad connection. I like to use pb blaster and spray all the connectors and sensors with it and using a pick I scrub off all the corrosion (normally turns green). then I use the same pick to close in the connectors and give better contact once I plug them all back up.

Try to ohm out the injectors first that way you make sure they're all good and if that's the case do what I mentioned above and let us know how that goes.