I just did a engine swap on my 03 350z track edition. Once we got it running it had a pretty tough idle and a slight back fire at idle which got worse as you drove. Can't figure out why, everything is hooked up right and air to fuel ratio is good as far as I know. Was wondering if anybody could help and curious if it came out of a touring model etc. if it would have different codes than one that is a track model maybe? Help?

 

Is it a misfire? Maybe you switched the plugs for two of the ignition coils. Unplug each coil pack and see if the car runs worse. If you unplug one and it doesn't seem to make a difference than you have an issue there.

 

^thats what i was thinking. The rear two coil packs on the drivers size are easily swapped because of the length. Look at the off color wire that is the signal wire and verify with the FSM for each coil.

 

I made that mistake when I put my motor back in. It is real easy to swap those two plugs.

 

yeah i had to double and triple check when i did my wire tuck. My car was down for 6 months and the wire tuck was performed at that time...started up like a champ.

 

I made the same mistake as well...made the car sound like a Wrx

 

That might help I put all new plugs in. I had to swap one side of the coil packs with the old ones because the valve cover was cracked during transportation and got oil on them so I might have mixed them up. The check engine light was on so I read the code, and it was a crank sensor. So I bought a new sensor which helped the idle some what but still back fired and it seemed to not be as torquey as it used to be. Thanks for the help btw way guys