rough idle, acceleration
 

Hey guys. So one day my 93 300zx NA was running fine, it sat for a few hours while I was at work. I started her up and once it started to warm up it began to idle a little rougher then usual with a weird sounding exhaust tone. By looking at forums and talking to a friend of mine I tried a fuel addative figuring maybe my injectors were dirty etc. So I did that, it started running normal again for the most part, shut it down again and it sat for about 2 hrs. I come back out and it is idling even harder then it was before, ABS light, battery light, and ebrake light were on and haven't gone anywhere since. When I accelerate past 4,000rpm the abs light turns off, then when I get between 5-6000rpm under a load(uphill) the battery and e brake light turns off then my engine temperature gauge drops instantly and goes back up. When the rpm's go back down the lights all come back on. Seems like it could be just about anything at this point with all the research I have been doing. If anyone has any insight or knowledge on this same problem any help would be greatly appreciated, Thanks!

Your injectors should not be the problem since you said it happens when it gets warm. This should be related to faulty sensors. Unplug both o2 sensors and start it up again. If the problem solved, you need new o2 sensors. It could also be your coolant temp sensor. Are you getting any codes from the ecu? The water temp gauge that you said fell down and raised back up again, could be a loose connection or corroded connection that wiggles around with the engine vibration. Both your coolant temp sensor (yellow plug) and water temp gauge sensor (single wire) are located on the hard coolant pipes in front of the engine. It is right behind the fan and should be fairly easy to see and accessible. Make sure you check for loose or corroded connections. If corroded, clean them with parts cleaner and a brush. If loose (specially water temp gauge connector), tighten them. Let me know what happens and if you got more questions :)

I have 1990 300zx N/A cold starts I have to hit the gas pedal to help it turn over, once running it's rough. Feels like one cylinder is misfiring. All I have done has done all new spark plugs, and fuel system cleaner.

The car drives pretty good, accelaeration is pretty good, throttle response is good, only at idle it's rough. When I blip the throttle at idle the misfire feeling goes away until it comes back to idle. Im hoping it's not an injector...

I would appreciate any information, advice and help with this matter thanks in advance.

Any recent work??
 

I had a weird problem like that, where my ABS, BRAKE, and HIGH Beam lights came on after i had some work done. Also a rough idle, shutting off and bad drive overall. This was all caused by an electrical short on the wiring under the dash. As another member mentioned, checking O2 sensors and temp sensors are a good starting point, but also check for burned/exposed wires around the dash or anywhere else for that matter. Good luck.