Surging after timing chain replaced
 

I have a 2008 HHR LT 2.2 and my dad just replaced timing chain and the fixed black guide, which was broke. The car runs great when you give it gas,but when you left off the gas or are at stop light or in park the engine surges and sounds like its going to quit, but does"nt. The engine starts with out any problems. He also gauged and replaced the spark plugs. Does anyone have any advice?
Thanks, han92:smile:

Perhaps the valve timing is off, chain could have slipped before or during replacement.

Welcome to the site

Timing could be a problem but in most cases if the timing chain is off a tooth or two it would set a trouble code for timing correlation.

I would be checking fuel psi and or throttle body issues before ripping it back apart.

X2 to both replies above, it can be all to easy to get a sprocket out of index, and another issue can mimic jumped timing.

The important thing is to remember that Ecotec engines are "Interference" engines, so you may wish to rent or borrow a borescope to ensure that the pistons and valves haven't conducted an impromptu "get together" already.

P.S. :welcome8: to the forum, and keep us posted as to what you find.

A. the plugs should NEVER need "gauging", they can be damaged they are not the old fashioned plugs. (they are properly gapped out of the box)

B. after a timing chain replacement the Crankshaft Position Sensor must be relearned. That must be done with a scantool that costs about $10,000, most shops have one.

I am surprised that you don't have a Check Engine Light.

I'm with Don, here put in new plugs AC Delco 41-103 iridium plugs only do not gauge gap them! Disconnect the battery for 30 minutes at the neg terminal of the battery in the spare tire well, this may reset everything back to normal but you may have to have the crank position sensor relearned. This could also be the timing chain tensioner is weak, search that there is a great how to!
Welcome to the site!