Engine Knock with Roush Supercharger?

[DrewT]

There hasn't been much nice weather since my local Ford garage installed a Ford Performance/Roush supercharger in my 2020 Mustang GT. This morning was the exception. I went out to eat breakfast and then headed home with the windows down. I heard what sounded like brief pinging when I applied sudden, moderate throttle at lower speeds. The sound was faint and very quickly went away as the car downshifted and the RPMs spiked. I never heard anything like this before the supercharger or before today but I haven't had the windows down much due to the cold weather we've been having. I filled the tank with 91 octane before supercharger installation and a couple tanks of 91 octane since installation.

I consulted the Ford service manager who helped with the supercharger installation and he suggested that I bring the car in. We went for a test drive and I reproduced the pinging sound. He thought that it sounded more like the cams resetting when you step on the gas, not engine knock. He hooked up the analyzer and measured the cam phasing while we reproduced the sound. While cruising the cams had a fair number of degrees of offset (if that's the right term). When I stabbed the pedal it immediately went to zero degrees which he said is normal. I'm not convinced but I'm not a mechanic.

He's going to contact Roush to see what they have to say. He is theorizing that the Roush tune modified the cam behavior which might cause the sound to be noticeable. In the meantime I'll try some 93 octane gas as I'm nearing empty anyway.

The car drives fine otherwise. I've been going easy on the car until I get 500 miles on the supercharger. I haven't gotten anywhere near redline yet.

Anyone with the Roush supercharger experience anything like this? Thanks for your input.

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[ice445]

Log KR (knock adder) and see if you get large positive corrections when you stab the throttle at lower rpm. If it's shooting up to 10 then it's real ping. If it's not, then it's something else. These motors can be very noisy at times, like the famous 2k rattle. Some cars also make more noise when making large phase adjustments for the camshafts.

It very likely could be tune related. My car makes more noise since flashing the FP tune, but after logging I made sure it wasn't ping. You'll only hear it if the car maxes out its correction factor.

 

[1SLwLS1]

I have occasional KR that I monitor with an OBD display from my truck. I don't know about Minnesota but in my regional experience, it is hard to find high quality 93 where I am at, and I am relatively close to the refineries.

I have been working with Roush to troubleshoot but you need to utilize their logging software, which is trash, and a J2534 pass through device if you want tackle this on your own. I tried with my local installer but didn't really want to leave it with them so it has been a long road.

I recently installed an updated calibration from Roush, which you probably have if you just recently installed the kit, but that did make it substantially less frequent. I have also never audibly heard pinging, only the alarms that I have set from my monitor. There are also some causes for false knock if you happen to experience that with a monitor, mainly low traction.

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