I recently purchased a 2008 G35 Sedan (automatic) that needed a new engine. I removed the original engine and harness and replaced with an identical engine. The car started up one time but now it cranks...there is a spark but won't start.

I am not getting any codes. I replaced the ecu and vcm with the ones that were pulled from the same car as the new engine. I also replaced the crank shaft sensors, battery, and had my key fob programmed to the new ecu. I have checked all fuses and they are fine. Checked my ground and voltages are fine. Fuel pressure is fine and there is plenty of gas in the tank.

I had the car towed to my mechanic’s shop because I was out of ideas and he has checked all the harness wiring, all connections, and had the key fob reprogrammed again to the ecm just to ensure it was done properly, but he is stuck as well. PLEASE HELP!



 

Why did you replace the engine harness? Why did you replace the ECM and BCM?

Put the existing ECM/BCM back in the car and try it again.

Is it throwing any codes while you are cranking? Is there a large KEY ICON in the dash while cranking?

Normally when the engine kabooms you replace just the engine. Need more details on why you needed to replace EVERYTHING including all those computers?

 

Basically you added 8x as many components that might have been bad when you replaced the ECM/BCM and wiring harness.

Did you verify the ECM was working before you pulled it?

Did you verify the BCM was working before you pulled it?

Did you verify the wiring harness was working before you pulled it?

Did you verify the 4 cam sensors and 1 crank sensor were working before you pulled them?

You created a LOT of potential problems by using components that were not proven to actually be functioning.

Put it all back the way it was with components you KNEW WERE WORKING. Original ECM, BCM, wiring harness, 4 cam sensors, 1 crank sensors. Any one of those items fails and the engine will not run. You know they were all perfectly functional before the original engine kaboomed.