ECMlink Need help with knock after HKS cam install

[jjw205]

Just finished my AWD swap, put in HKS 264/272's, now getting tons of knock for some reason. Car was tuned perfectly before. I can't tell if it is going lean, causing it to knock, or the timing is causing it to knock (only 3-5°...) and then go lean for some reason. I have a few clips posted up. Any ideas, let me know. I know the MAFComp isn't perfectly dialed in, but I was trying things to see if anything helped and it still goes lean before/during knock, depending on how delayed the wideband signal is.

 

[gofer]

It's your timing, a cam install means a completely new tune or else you'll get knock especially running 91. I recommend shooting for a rich AFR, like 10.8:1, to cool the CC and combat knock so you can run better timing advance. If you still get detonation running 10.8's richen it up even more, like 10.3~10.5:1. Running the 22psi you want and having better timing advance will give you better results than lean AFR's and no timing at all, in my experience.

The attached tune is for a 10.8:1 AFR target and still a conservative timing curve. See how she does WOT, keep the pulls from 3k to 7k (assuming it isn't knocking) and in 3rd gear. I didn't have any MAFComp data to tune AFR's below 700Hz so your MAFComp table may look a bit strange, I just smoothed it to the 700Hz point I could tune and I'll get the data <700Hz on your next pull from 3k.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[jjw205]

It's your timing, a cam install means a completely new tune or else you'll get knock especially running 91. I recommend shooting for a rich AFR, like 10.8:1, to cool the CC and combat knock so you can run better timing advance. If you still get detonation running 10.8's richen it up even more, like 10.3~10.5:1. Running the 22psi you want and having better timing advance will give you better results than lean AFR's and no timing at all, in my experience.

The attached tune is for a 10.8:1 AFR target and still a conservative timing curve. See how she does WOT, keep the pulls from 3k to 7k (assuming it isn't knocking) and in 3rd gear. I didn't have any MAFComp data to tune AFR's below 700Hz so your MAFComp table may look a bit strange, I just smoothed it to the 700Hz point I could tune and I'll get the data <700Hz on your next pull from 3k.

OK great, I will try that in the morning, thanks a ton.

I'm running 93 octane. I am also on 9:1 compression, so timing is a little more touchy. I have meth injection also, but trying to get the tune correct without it first obviously. That's why my secondary timing map was more aggressive.

I have it tuned pretty well <700Hz. Fuel trims are usually within 1% either way, so idle/cruise are not too bad.

I didn't realize you could sacrafice a little on the AFR (richer) to get a little more timing. That's good to know.

Will post up another log hopefully tomorrow, thanks again!!



Ran another quick log this morning. Knock seems to be under control for the most part. I may need to tweak the MAFComp a little more, but it seems like a good start. So is it safe to just advance timing from here? I plan on running a little more boost, I found a split hose to my wastegate, that's why I was running about 24 before. This log should be around 20 but I do plan on running 23-24. As long as airflow seems like it lines up well, I should be ok to up the boost a little probably.