Will my engine ever run right?
 

Engine made a tapping sound on cold start. Dealer says it was broken exhaust manifold. 1 week later, I pick up the truck and they changed a cylinder head and ordered me a new cam shaft actuator. No mention on the ticket that they even worked on the exhaust manifold. Engine runs much, much worse, very rough. Is the engine toast? Can it be repaired?

Give the truck back to the dealer and tell them to fix it right or you're not going to pay for it. There's a lemon law you know.

A cam shaft actuator....sometimes called a variable valve cam timing actuator is an intregal part of the Atlas motor running correctly. To make a long story short, your PCM can control valve timing based upon rpm and load, using oil pressure sent through a control valve to the cam timing actuator to change and adjust the valve timing constantly.

In other words, your motor is gonna run like crap (but it will run) if you you have a bad cam timing actuator since it is limited to the default/normal position.

When they replace the actuator, and it still runs bad, that is the time to make a stink.

thanks doc I will let you know how it turns out. I love this truck and just want it to work!

Hey Doc, I hadn't been back here in a while, but wanted to thank you again and let you know that the engine has been running like a top since the repairs! Despite that, I still say the the Hummer dealership here in New Orleans has got to be the worst group of mechanics I have ever encountered!

So was it the cam shaft actuator like he said?