Engine Noise
Thread Starter
Heel & Toe
Joined: Mar 2007
Posts: 21
Likes: 0
Engine Noise
I have an 07 C6 with about 11k miles. About 5k mile ago it started to have an engine noise that sounded to me like engine knock or pinging. Sounds to me like the noise you would have if you had to much advance. It only occurs under acceleration and only occurs for a few seconds. It happens as I accelerate moderately or hard and mostly going from second to third or third to fourth gear. I have had it in to the dealer and he could not reproduce it. Took time off work and went in and showed two people at the dealer how to make it happen. They told me that if it was engine knock that I would have a code and the computer said there was absolutely nothing wrong with the car. I have tried running all brands and grades of fuel and see little to no change. The dealer thinks I am smoking crack and has a hard time hearing what I hear. Has anyone else had this problem.
Le Mans Master
Joined: Oct 1999
Posts: 8,205
Likes: 40
From: Tucson AZ
Could be carbon build-up on the valves, etc. Try running some Chevron Techron (any auto supply store) with the next tank of gas. If this doesn't work, you may have to do a "decarbonization" procedure. This was a fairly common problem with the C5 cars and a search there (or here) should bring up some good ideas. Good luck. 
Thread Starter
Heel & Toe
Joined: Mar 2007
Posts: 21
Likes: 0
I did add a Techron additive but didn't see any improvement. Thinking about doing it again for good measures. I read the thread about the decarbonization. It talks about using a product called Sea Foam. I have never heard of this before. It also talks about using GM Top Engine Cleaner. Any experience with either of these. I read a can of Sea Foam at the AutoZone and it says to add 1/3 can. The thread you said to read said something about using the entire can. Help!!!
