Does anyone here experience any kind of engine knock, under any conditions? I get it
sometimes, but have not debugged the exact conditions that cause it. I have an A6 btw.

 

yep I HAD it. A6 too. Happened when cold or hot out. Usually when hitting the gas hard(but not hard enough to down shift) from cruising at around 30 mph. Pissed me off so much I had it tuned. No problem now.

 

Yeah, I have it too on my MN6 '07, even with 93 octane and trying all kinds of brands. How many miles on the car. could actually be carbon if you drive the car very easily. Trusted mechanic told me that these LS2's don't need alot of carbon to get them to knock, so don't be afraid to "burn" out the carbon. Mine has been running better since I started beating on it.

 

Get a tune

 

And void the warranty on a brand new motor that shouldn't be knocking anyway?

 

Put a can of Chevron w/Techron top engine cleaner, or GM brand top engine cleaner in the fuel tank. Take it on a highway blast holding it wide open a few times, that will clean out the carbon and stop the knocks. That one advice was very correct. LS motors, Northstars ... motors like that have tiny combustion chambers and quench areas. The slightest build up can cause knock. On a Northstar the piston to head clearance is so tight, a little carbon can actually cause the piston to hit the head on a cold start. Now that's a real knocker. Those really need a thorough top engine cleaning. The LS motors generally just need a good highway blast with cleaner in the tank.

 

try what michrider suggested. It cant hurt but it did nothing for me. Or get a tune. Warranty didnt mean much to me if i had to drive a car that knocked. I rather enjoy the car. The tune did that. If you take it to the dealer they will try the top end clean as mentioned but they will not adj anything so..................

 

I just had it out at the track - Buttonwillow - about 40 days ago. Did about 50 laps. Breaks in between, of course. But i was really on it for each lap, about three miles, about 12 laps at a time. But, no cleaner in it.

I don't remember it doing this in the the beginning. 14k miles, and 2 track days.And, i drive it pretty hard. I guess the cleaner wouldn't hurt, however.

It only seems to knock in paddle mode if I get on it, and am not at the lowest gear possible for my speed. If I am a gear higher, it knocks a little. Guess I need to keep the RPM's higher at all times.

 

Don't the valves open a half inch or so? How is a little carbon on chamber come into contact with the piston? That doesn't make sense to me.

 

Mine pinged/knocked from day 1. Had it tune, no more problems.

 

there can be many reasons why knocks occur in an ingine and can be frustrating in dermining what the issue is. it can be an internal mechanical issue in the rotating assembly which is highly doubtfull. Most of the are caused because of ignition and fuel issues where the air full mixture isn't being ignited as efficiently as it needs to be. Hence the reason others have gotten rid of the knock by getting a tune. I like you don't wish to void a warranty so that's probably not an option. Since the car is still under warranty I'd take it in. I'll work on mine myself when I don't have a warranty. You paid a lot for your car and should enjoy driving it not wondering about the knock. Also, It would be very rare that a valve would be hitting the top of the piston creating the knock. The engines are built with valve/piston clearance regardless of timing. Even at the top of the piston travel enough room is available for clearance of the valves regardless of timing. (as long as you haven't installed a high lift cam and increased the rocker arm length you shouldn't have to worry about that).

I once built an engine with a bunch of buddies and a keg of beer and forgot to torque a rod . uh oh click click..knock knock so I learned a lot about knocks!

just a ramble but take it in for warranty

terry