ok long story short, I bought a 300zx from a friend who had tried to do a headjob on the car. When I got it it was half taken apart ( heads off)
and I pulled the old motor and installed a new one with low miles but i cant get it to run smooth, changed the plugs, made sure each coil is firing good,
Now I have never worked on these cars before and I didnt get to take it apart which is my problem...were do all the vacuum lines run specifically...?
I have no literature...no tear down expereince on this motor, I have all the plugs in right places (99% sure) and it just idles ruff and revs like it has a miss....Motor came out of running driving automatic car..and wasnt beat on!
Any advice, thanks in advance

 

I see the problem. You own a 300z. First Mistake. Anything that needs to be done on these cars 99% of the time the motors have to be pulled.

Good luck. Contact Z fever.

 

Check timing..

 

LOL, Thats what I though when I bough the car...WHAT A PAIN to work on, But its really not that bad mechanically, but there so many wires, and vacuum lines on the car that I think I have something in the wrong place...The motor was running fine in the parts car..so I know its not timing...

 

There are lots of possibilities which would take a long time to go into to, but here are a few all harness related cause the harnesses suck

-Bad or coroded injector connection
-bad or coroded coil pack connection
-bad or coroded ignitor harness conection (passenger side of the front engine cover)
-bad or coroded cam angle sensor connector(driver side of the front engine cover)

Try wiggling all these connections. Also pull off coil pack plugs one at a time to see if it is one(or two) specific cylinder that isnt firing

If you cant figure it out, feel free to give us a call and we can check it out

 

what year?

 

An ECU Check might help uncover a problem(s). Give that a try.

 

It could also be your wiring harness mess with the injector and coil connecters while its running and see if it changes anything.

 

Check all electrical connections Charles mentioned, alot of times the old harnesses have green and corroded terminals at the coil/injector/cas plugs. If you can't replace your harness, try a small eyeglass flathead screwdriver to scrap the terminals, it worked for all 4 of my dead cylinders when the injector connections were corroded after a TT swap.

 

Got it running and not bad actually, I just had to compare another 300zx car. It runs decent but stalls sometimes on hard deceleration, overall its not bad, does a killer burn out, Thanks for the help guys.