Hello my names josh, this is my first car im not rich in anyway so i do all the work myself but i need help! please and thank you to anyone that can help!!!! , my 1985 Nissan 300zx has 324xxx miles on it and iv run into a problem , just recently i replaced my MAS, fuel filter, fuel pressure regulator, rotor, dizzy wires and my spark plugs. trying to make it run better which it did for the last couple weeks , but yesterday after driving home from California to Reno i stopped somewhere shut it off for about 20 minutes and when i came back out and tried to start it, it started really rough the idle was low and rough and i heard it misfire , and it died two or three times before it finally ran just good enough to get out of the parking lot, but here is the kicker , as soon as i went about 100 yards or so it smoothed out and ran like nothing happened and at every red light the idle was smooth and perfect, i have no clue what might be causing this rough start when warm and the fact that it smooths out confuses me... ANY help would be greatly appreciated!

 

Step #1, check ecu codes.

 

ok ill check tomorrow morning, thank you, ill post if it helps, your the best

 

codes unlikely to be any help. unless they say the chts is shot which is a likely culprit for what you describe. you say you replaced all that stuff BUT what is the fuel pressure? what is the vacuum? 324K on a z31 is getting up there. they are pretty tough but?

Here is my general advice to at least eliminate the simpler things.
Get your battery load tested (better yet buy an Interstate battery and be done with battery woes for better than 5 years). Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone. If you have the electro adjustable shocks they are DEFINITELY GONE.

 

Hi Mate,
I had the same problem which randomly turned out to be the spark plugs that I had used and the gap that I set them at. Take them out and soke them in thinners wipe them dry and re-gap.

Gav

 

lol ill give that a try Gav , thank you

 

haha so i figured it out, didn't check ecu codes . but the problem was my power transistor, and my ignition coil. so i upgraded my ignition coil by getting a ignition coil off of an old ford at my local pick n pull and it runs better then ever haha, thanks for all the help