Knock on throttle let off

[robzz]

Hi all, long time reader, few times poster here.

I've search quite a bit but found almost no thread about knock on letting gas off. A lot on tip-in knock, but few on the other way.

I see IAM getting adjusted down because of knock (FLKC) reoccuring. However, from what I can see, it's mostly when I let off the throttle. I see some minor knock on hard pulls, but IAM is never adjusted down soon after.

It also appears when I give less throttle. Let say from 10% to 50% and back to 10%. And mostly at low to moderate RPM (2500 - 4000).

Mods are a Gruppe-S UEL catless header, mishimoto intake tube, Perrin panel filter, invidia q300 and an OFT.

I've seen the phenomenon on V2.76 tunes, V2 OFH optimized, and V4.

Here are 3 datalog I think represent the issue. The IAM is'nt changed on those exemples, but the phenomenon is represented.

Any input will be appreciated!


https://datazap.me/u/robzz/10-v2-26?...zoom=8320-8402

https://datazap.me/u/robzz/09-v2-25?...zoom=3605-3870

[steve99]

make sure you don't have ant exhaust components like over pipe hitting on chassis as this can cause false knock indications.

your ltft seem quite high at +10 % check for exhaust leaks


do you have stock intake ??

[robzz]

Thanks for the reply!

I'll have a look for bruises on over-pipe. From memory, it did'nt looked near anything but I'll check anyways.

For LTFT, I know they are high, particularly at idle. I "MAF scaled" it when it was a little cold outside (50°F) and those last log were taken near 75-80°F. Spring finally arrived!

I have a sorta stock intake. I have a Mishimoto Intake Tube with a Perrin panel filter. I'm pretty sure I have no leaks on the tube.