I did a head/cam swap about 3 years ago. for the past 1.5 years the car will periodically not start. its gotten worse. about 50% of the time if I go to start it, it will fire right up. If it doesn't, I have to leave the key on for about 10 minutes before it will decide to start. I have good fuel pressure when it acts up, but no spark or injector pulse. So obviously it isn't seeing RPM signal... I have all security disabled, new crank sensor, and I checked over all the wiring/grounds everything seems good. I have a new PCM also. Any ideas????? Im gonna put a cam sensor in it when I do my LS6 intake swap in the next week or so. Just curious if someone has had this problem before... Thanks!

 

Sounds like you're going about things the right way. Hopefully the cam sensor solves it. Just curious, have all of the "new" parts listed been installed since it started showing symptoms...or were they installed before the trouble started? Just trying to clarify here...

 

All parts were installed after. And I also have done a Cam/Crank re-learn.

 

Crank relearn is just for misfire detection....but good thing that you're covering all your bases. Seems like it's down to either cam sensor, or the wiring to the cam sensor or crank sensor. Hope ya get it sorted out soon

 

All of your security might not be disabled. Mine did this and needed a new ignition switch and new keys made with a new code. Leaving the key on for 10 minutes is a bypass for the security from what I found on here.

 

AFIK, leaving the key on is not a bypass for the security system. From what I can remember, you have to cycle the key on in 3 ten-minute intervals before the car will start with a security system problem.....total of 30 minutes before the car will start. Again, this is just going from my memory.....which ain't what it used to be. Lol

 

I would replace the ignition relay under the hood. Seen a ton of them go bad and do the same thing you are having a problem with.

 

thanks for the tips!! ill throw an ignition relay in tomorrow!