10th May 2011, 20:00

I had the same problem. I followed the instructions and cleaned the Mass Air Flow Sensor with the CRC cleaner. This resolved the problem. I was able to haul my boat with no knocking for once.

11th Jun 2011, 21:32

Ditto. I had the same problem, and resolved the engine knocking by cleaning the MAF sensor. It was easy enough and resolved the problem. I can now tow my boat without hearing the knocking sound. Excellent suggestion..!!