2005 MCS died literally less than a mile from the house. It cranks, delivers fuel and sparks like crazy but will not start. Back fires, got to be timing. OBD2 says cam position sensor.
Took valve cover off and found the brown colored plastic portion of the timing chain tensioner off to the side and chewed up. Evidently it came off and got between the crank or cam sprocket and the chain. In the process of this I believe it allowed the chain to slip over one of the gears and nw the timing is off.
Can anyone recommend how to re-time the motor. The only reference I have is the mark on the cam gear and TDC.
thanks

 

You need to pull the lower timing cover and use the timing marks on the lower sprocket, and cam sprocket.
I've seen this happen before so I now keep the guides, and chain in stock. Glad you caught it early, the last car we put a motor in.