Hello all,

I have a 2003 G35 M6. I decided to change the gaskets on the valve covers and the spark plug tubes. Everything came apart fine, and I put it back together, no extra bolts. That's the good news. The bad news is the car cranks but doesn't start.
Does anyone have a common set of things to check that would cause this? I presume I have either left something unplugged or reversed some connector.
What would be the main plug that could be forgotten when doing this job that would cause a non-start but only cranks?
It's not my first car to work on, but it is my first G35. I'm trying to think where the main connectors are for spark or fuel.

Thanks for any thoughts on common mistakes when doing this job.

Most common thing is swapping coil pack harness wires.

Every coil pack has 3 wires, one is black, one is white/blue stripe. The 3rd wire determines which cylinder it is.

1-yellow/red stripe

3-blue/red stripe

5-purple/white stripe

2-green/red stripe

4-grey

6-grey/red stripe

Well, I found the problem. I guess because my flashlights were getting dim, but there was a ground wire from the ECM that I missed and forgot to tighten back onto the block on the drivers side. Started right up afterwrds. Thanks for the suggestions above, it's what made me look more carefully.

Glad you got it all fixed.

Thank you for posting this. I had just put back together everything after replacing my valve covers and the car was running rough. I was about ready to hand it over to a mechanic and see if he could figure out what it was. Turns out I just swapped 2 of the coil pack wiring things. This post saved me a lot of frustration thank you😁

That ground wire problem (I think) is also a very common one. When I did my valve covers, I tore free one of the ground wires in the front of the car going to the engine. Took me a little wire before I saw that was the issue. Same thing, crank but no start.