knock on gauge but not scanmaster


Active Member
Aug 8, 2018
thinking i have false knock but not sure yet. for example this morning caspers gauge was in the red and the scanmaster was at 0.8 deg KR. of course I let off. I think it may be shifting related. I have noticed I am getting erratic knock on the gauge. in the green on the gauge and nothing on the scanmaster. is this because the slow scanning speed of the ECM?

i will have to go thru what has changed since last season. new downpipe. ta49 turbo, MAF translator and MAF.
Trust the scanmaster before the caspers gauge. I believe the scanmaster updates every 1.3 to 1.5 seconds or something like that so it could be possible its missing it (if you have a fast update patch on your chip it will update about 3 times faster). Also could also depend on when knock is happening for example if your chip has a knock retard ignore feature under a certain mph.

If you added an aftermarket downpipe, they like to hit the frame or anything else nearby. Inspect closely to see if there are any marks indicating contact.
the DP has about 3/8" clearance but may be bad motor mount. I will check the easy things first. motor mounts, blue the frame and see if the DP is hitting. install the stock MAF and see what happens.
I have a Casper's audible alarm. It will chirp sometimes & the Scanmaster doesn't display anything.

Whichever warning you receive first.
Old MAF same knock. DP Is hitting the frame and driver side engine mount is bad.

Reading some old threads on here is the GM mount still better than the parts store one ? This one lasted 2 years. Not wanting poly