Please educate me on knock.

[BoyofBeef]

Hey all,

Finally getting around to do some logs and getting a basic understanding of how engine management works.
Just wondering about knocking. What would/do you expect to see.

I'm running a Toyota crown, 1JZ VVTi with a Holset HX32, Link G4+ Fury, Tial External gate, Walbro 255, FMIC, blah blah blah...

Car has been running over a year with no issues, pulling hard, dream to drive, and I've been too scared to even plug a laptop into the ECU before now.

I finally went for a blast today, doing some varied driving, and at WOT I noticed a huge increase in knock. Now this is close to the threshold that my previous tuner mapped the car to, but do you guys have any additional input? - From my inexperienced eyes, it looks like I'm getting considerable knock when target boost is being reached, but I'm wondering if it's a false-positive from the external gate, OR am I just being paranoid - Knock just increases when you give it a bootfull.


Thanks in advance.
KR
Beefy.

 

Log 2021-04-29 7;04;41 pm.llg

[Adamw]

"Knk Level Cyl*" is just the level of noise coming from that cylinder, it will increase with RPM, boost, ign timing and many other variables that effect the mechanical noise inside the engine.  The level of noise above which you consider it to be knock is determined by the knock threshold table.  The knock threshold would generally be determined by the tuner by ploting the typical noise levels when the engine isnt knocking, then purposely making it knock and ensure the knock level exceeds the threshold reliably when it knocks.   

In my opinion your threshold doesnt look well set especially around 4-5000RPM where knock would most commonly occur - you have a knock level on the noisiest cylinders only around 160 but the threshold is set at 615.  A threshold around 300 would have a better chance of catching knock if the typical level is only 160.

You should generally have knock threshold ploted on the same graph as your "Knk Level Cyl*" channels so you can see if any are getting close to or exceeding the threshold.  Example below.   Note the newer layouts supplied in PC Link - either 1920 x 1080.llf or Default_1366_x_768.llf have a knock page set up.