Pulled engine out because after the engine overheated it quit and there was zero compression. I discovered 3 pistons were damaged (holes in the top of the pistons in the rear of the pistons near the exhaust valves); so I replaced all 4 pistons with new ones. I replaced all valves (intake and exhaust) and installed a new timing chain and sprockets. I balanced the shaft chain and sprockets. Re-installed engine and hooked everything up. Now the engine tries to start, but doesn’t. Not sure what could be wrong. I haven’t checked the compression yet. It has 50lbs of fuel pressure, has spark, and the battery is good. It also showed two DTC’s (P0107 and P0340). This is my first time working on the Ecotec engine. I appreciate any suggestions as to where I should go from here. I will also appreciate any information as to how the hydraulic valve lash adjusters work. I noticed that the throttle plate looks like it is open more than it should be. Thanks in advance to anyone who can help.

 

How did you set the timing gears/chain?

 

I lined up the timing marks on the sprockets and the colored links on the chain.

 

There is a tool for the cam/crank alignment, and you have to get the timing right, then install the chain

 

I really appreciate you taking the time to respond. i bought and used the GM 4 cylinder cam tool set. i lined up the timing marks on the sprockets with the three colored links on the new chain kit. i rotated the engine a couple of times to be sure there wasn't a problem with the pistons. It turned over like it should, without hitting anything. i don't believe that's the problem. i have noticed the throttle plate in the throttle body looks like it is open more than i would expect when trying to start the engine. i work with fuel injected Harley--Davidson motorcycles all the time. This plate looks like its open 10-20 degrees. I can push it shut and it moves a lot before it closes completely. i know it is supposed to be open some, but this doesn't look right. Don't know what else to say. Thanks.