Pre-ignition/Engine knock

[Craig-o]

I have recently noticed under hard acceleration that I occasionally hear an engine knock. My 2001 is stock, with some performance tuning modifications (software only) and 61,000 miles. I always run 91 octane or better.

The tuning was done only about 3,000 miles ago, and the knock sensors checked out OK, so I don't think it's that. Any ideas?

 

[Mr. Lucky]

I have recently noticed under hard acceleration that I occasionally hear an engine knock.

[. . .]

The tuning was done only about 3,000 miles ago, and the knock sensors checked out OK, so I don't think it's that. Any ideas?

Are you sure it was the knock sensors that were checked? It seems unlikely, since they are located beneath the intake manifold. I think it was probably the O2 sensors that were checked (which would be essential to proper tuning).

See if a new tank of gas helps. Also, what is your oil consumption like? GM used a different type of rings in 2001, and many LS1s burn oil as a result. If yours have deteriorated to the point where oil is slipping past them into the combustion chamber, then it might very well cause a full-throttle problem.

 

[c4c5specialist]

HI there,
I would suggest adding one 20 oz bottle of Techron fuel system additive and see if it goes away before considering more expensive problems.
The TUNING is something I would get rid of, unless you are heavily engine modified.
Allthebest, c4c5

 

[DanHammer]

You can also try Fuel Injection cleaner ... or octane booster additives, just make sure you get one for unleaded gas. I always use injection cleaner on a regular basis, every 5th tankfull of gas and do not have ping or knock problem on my 2001 modified engine. That techron fuel system additive as suggested by c4c5 is a good choice of brand. Hope this helps you.