I have a 1991 300zx na
it runs but has a serious miss. Checked all the coil packs and plugs, injectors are fine and went throug the fuel system and everything is fine. Only deos it when thereis a load on the motor just sittingin nuetral it deosent do it. No cel. Im lost any suggestions?

 

Did you run the ecu diagnostics? Just because there's no CEL, doesn't mean there aren't any codes...

 

same **** here. getting worse by day. didn't drive the car for 4 months but im working on it again. new injector seals, new gaskets for cam top. a local mechanic told me that its very common with nissan t have a defective water sensor which messes up the rest of the car. i personally don't see why it could be the cause but when im done with cleaning and replacing some gaskets and seals and have it back together after also checking all connections and cables again, i will chefk that next if its still not running well under load. keep me posted if you find anything first

in my case no error codes

 

You didn't say if it runs crappy when cold too - so hard to know if it's temp related. That's usually how a 'water sensor' (CHTS?) acts when it's bad. Idle cold is fine, engine warms to temp, runs crappy. My guess is a sensor is sending bad or no info to your ECU. Temp related?

 

in my case the idle jumps up and down all the time and is way too high in general and runs same shitty cold and hot. i cleaned the idle valve and nothing changed. im not sure if thats related to the problem with the engine running on throttle, i think its another issue because the idle problem was always there since i bought it but the engine started off ok but not as much power as it should have and then got worse and worse. it would run only in idle and slightly throttle. everything more then couple mm throttle and it would turn down and just run as if the battery can't spark the engine. black smoke all the way in the end. unburned fuel etc. but thats my case. we could have the same problem

 

OK, from a Z31 perspective, I gotta suggest Air Regulator. On a Z31 it can make the idle do that and also make for bad fuel burns - unless everything on it is connected right and working right. Do you have the equivalent on your Z32? Or, (thinking Z31) your ECU is getting bad info from a sensor - crank angle or throttle position - or no info at all... Sorry can't do more than guess or suggest...

 

i think you might be right. the cables are pretty old. some are just twisted together. some fool owned the car and raped it and I'm trying to fix everything they messed up. first thing i bought was the MAF but nothing at all changed. well lets see. still waiting on the injector seals. once i got it all replaced, i try to get that plenum back on, which will be most likely a nightmare. they must have monkeys working on that car with tiny little hands that fit beside the engine.