I'm working on a 2009 GMC Sierra with an LY6 all stock. The engine will quit and throw a P0016 cam/crank correlation code. After all of my diagnosis so far, I still can't figure this issue out. When cool, the engine starts and runs normally. When it get hot, and the oil pressure drops to about 20psi, it will quit and set the P0016 code. It will NOT restart until usually the next morning. Here is what I did so far:

1. replaced the ECM
2. replaced the crank sensor
replaced the cam sensor
replaced the oil pump to a M295HV
replaced the cam phaser, timing chain crank sprocket and tensioner and cam bolt valve
replaced the VVT solenoid
replaced the TPS
checked all grounds to coils and injectors
Checked fuel pressure
Has spark and fuel
replaced cam sensor (GM)
replaced crank sensor (GM)

When it's running normally, the cam variance will display .500 degrees and is stable but will display maybe 1.9 degrees when revving. The cam variance will also display .500 during cranking followed by a normal start. However, when it quits, it will display 19.3 degrees while cranking and then quickly drop to .500 degrees, sometimes sputter, and then go back up to 19.3 degrees and won't start. Yesterday I ran it until it quit when the oil got to 203F and the oil pressure hit 20. I drained the hot oil and put in cool oil with some Lucas treatment and I got it start after a few times cranking. It ran longer but eventually quit and wouldn't restart until this morning. So it needs oil pressure higher than 20 psi to keep it in time.

When I put the new phaser in, I rotated the engine until the timing marks lined up on the old one. Thinking back, I remember seeing the cam gear on the old phaser turning slightly without moving the cam but I can't remember if I was turning it clockwise or counter clockwise during that. When I installed the new phaser, I'm a 100% sure the marks were lined up and have a photo to verify it.

But it seems that the timing is off when these no start situations happen as verified by the cam variance and it happens when oil pressure is low and oil is hot. From what I understand about the VVT phaser is that it locks at 0 when there is no oil pressure so the timing should not be off, but it apparently is. If the timing marks were lined up during install, then I should be golden. I'm wondering if it was off a tooth and the oil pressure was needed to bring it back in phase, that might explain why it only runs with oil pressure above 20. But on the other hand, how could it be off a tooth if the marks were lined up?

I am completely stumped but I hate giving up. If by any chance it is off and the VVT is adjusting the phaser to bring it back in to time during a cool start, if I disable the VVT in the PCM then it shouldn't start under any condition. In other words, the timing would be off under hot and cold conditions.

If you can follow my rambling, I'd like to hear your thoughts on my logic. Below are the timing marks as installed and the screenshot showing the timing variance between commanded and actual.

 

I’m getting a pico and will see the timing events and if it really is off

 

What thickness oil are you using? The factory spec is 5W-30. If you use the now very common 5W-20, it might just be too thin at hot temperatures for your engine. You might even try e.g. a 5W-40, which is still common for European cars.

 

I had 5w-30 in it and switched to straight 30w and it's the same thing. From my understanding, oil pressure should not have anything to do with the VVT system at idle when nothing is commanded. The minimum listed in the service manual is 6psi at idle. Ironically, a few years ago, it had oil pressure as low as 10psi at idle and never had any issues. An oil pump change was the fix.

I'm going to attempt to scope the cam and crank correlation to see if there is a difference in the timing from a good start and a no start. It should also let me see ow clean the signal is from both sensors. I even tried a second replacement cam sensor (AC Delco) with no change. It still also could be a grounding issue and I could replace the harness to rule that out. They seem cheap enough.