Corvette C7 Z06 Knock Retard

[maxwell]

Hello everbody,

my Corvette 2016 C7 Z06 shows knock retard whenever the vehicle is not in steady state.
Even at slight tip in. First I thought it's all false knock.
Now I saw knock retard also at high RPM during a WOT pull which looked real, cause it was shown which cylinders were affected.
I also have the feeling the car ist running a litte too lean because the exhaust tips dont get that black anymore
and coolant seems to get a little hotter.
Vehicle is running RON 100.
Does the engine might have a problem?
How could I investigate it?

best regards
Max

[djyankees31]

To me it looks like you are running to rich when the knocking started. Before knocking, 0.86 lamba, during knocking, 0.74 lamba. At least that is what the tune is commanding. I don't see that you are logging a wideband to get the actually EQ.

[maxwell]

ah ok, did not recognize that.
Unfortunately, I have no wideband installed yet.

[TriPinTaZ]

I've seen this happen when the intercooler isn't properly bled and leaves large air pockets in the blower exchanger bricks eventually causing the pump to shut off. I don't really see your MAT getting up there though so not sure that would be the issue.
Needs mods and tune file to see if something is out of the ordinary or if you have a mechanical issue.

[sevinn]

Looks like it's showing the knock once cat overtemp kicks in. I'd suspect it's overly rich.

[maxwell]

The only change is a high flow air filter.
I bleeded the intercooler system last year with a vacuum pump. Worked very well. I will try torco and experiment with fueling.

[TriPinTaZ]

The only change is a high flow air filter.
I bleeded the intercooler system last year with a vacuum pump. Worked very well. I will try torco and experiment with fueling.

Stock filter housing with a "high flow" filter such as the BMS? Or an entirely different aftermarket intake? What brand?

I did some testing when the BMS came out and found that on the stock tune the BMS drop in greatly increased the knock retard on the scanner. I don't think it was real knock but it essentially lowers the airmass calculation. Your log shows boost pressure is above stock level but airmass is below it. You're probably lean down low causing knock. Additionally the lower airmass across the board, especially up top added more timing than you should be running. This is also contributing to the knock.

Do you plan to tune the car? The "drop in" no tune filters are not really no tune in my opinion. They greatly change the MAF's airmass reading just like an aftermarket intake would.

[maxwell]

Yes, it's the oem housing with dry attak blue air filter

[maxwell]

You're right, I bought an OEM air filter and the knock detection changed!
Also got a wideband now and will check the fueling with attack blue filter installed.
Factory tune is super rich at high rpm.