Hello, new here and I have one that I cannot figure out. I work for an independent shop. 2009 Enclave with 3.6 came in. Was diagnosed and we replaced the timing chains. After that was done the car will not start. It cranks and will fire for about a second then shut off. We have no codes. We have spark and fuel. We did a compression test, the dry test was rather low across the board but the wet test the PSI would skyrocket past 200. I have checked the timing and am 99% it is correct. I've unplugged the MAF and tried that way to no avail. I read online about holding the accelerator pedal halfway and that seems to help more than not holding it at all. I have smoke tested it and no leaks. No blown fuses that I can find. If anyone has any idea that would be greatly appreciated.

What'* the theft light doing?

Security light goes off after a couple seconds like normal.

The way you explain this sounds like you are not very experienced. You should know without a doubt if it'* in time. I'm going to say it'* not.

I was concerned about the "99%" also.

Were all four cams mechanically held in place during the swap?

Did all of the marks line up correctly just before the chain cover went back on?

Were guides replaced?

After that, check fuel pressure and check for spark. I'm curious to know if it has enough of either when it quits. Curious about fuel pressure in all conditions while we're here.

What was the original diagnosis that showed that cam chain replacements were necessary?

How many miles on the car?

I’m rather experienced. I’ve done these before. All marks were lined up before front cover went on. The reason I say 99% because you can’t verify all the marks once the engine is back in the car so if something happened after I put it back in and it jumped for whatever reason I would have no way to verify that without pulling the cover. I did not diagnose it. Customer was told timing chain’* because of low oil pressure issue. I was just doing as I was told and replacing parts. I have spark and fuel but seems to me like something is lacking or disappearing after it fired up.

Timing chain for low oil pressure? What kind of shop is this?

I have to agree. I don't see the correlation where timing chain issues of any sort would cause low oil pressure.

I could see low oil pressure potentially causing issues that might lead to replacing the timing chains as part of a fix, but that'* even a stretch.

The reason I suspect something out of time is that (besides the fact that that is what was changed most recently) It starts with the phasers at zero (or very low) oil pressure, then immediately commands they go wherever they are supposed to go in the next moments. If something is out of time and that command is active, it could time itself into a stall.

Were all four cams mechanically held in place during the swap?

Were guides replaced?

What is the fuel pressure key on engine off, engine running, and during the stall?

How many miles on the car?