Maybe one injector aint spraying and that cyl is knocking. The afr will still seem rich for the whole exhaust but one cyl could be at 14.8 afr.

 

Update:

Last night I flashed back to my previous ROM, and went for a couple of hard pulls... No bad knock (1-2 counts sometimes)

Today I analysed the 2 ROM's, the ONLY differences where a slight lean out in the 36KS area by 0.2 AFR.

Now I re-calibrated the WB yesterday - so here is my pull from this morning (back on the previous ROM):


Now obviously that 11.9 spike is worrying, and by leaning out another 0.2 would have put it just short of 12.5AFR... Could that really cause massive knock?

 

Back in the day when I was first using EvoScan and logging my original Vishnu mail-in flash, I found knock to be very unpredictable. On some runs, there would be no knock and on others I would get spikes of 15 or more.

 

I remember now what my conclusions were on the cause of the knock. It seemed to be due to three combined factors: restrictive exhaust (stock) + high boost (22-23 psi when it would happen) + a slightly too lean AFR. The high knock counts would typically occur at around 5000 rpm. I didn't have a wideband at the time to measure AFR, but I found that richening up the AFR value in the fuel map by about 0.2 along with lowering boost slightly eliminated the knock.

I know you have a 3" exhaust, but don't you still have a cat?

 

Well I have _never_ had knocksum greater than 10 on my car..

I have modded the maps a little so hopefully I can fix that 11.9 spike and lean out the rest a tad more..

edit - Got a mil.spec cat

 

There is no way that much knock would be caused by mixtures that are still that rich. Did you flow test the new injectors before putting them in? Maybe one injector is a little down compared with the rest. I have had brand new injectors we have bought for customers that flow unequally. You should never just test them at full flow (100% duty), we test them at various duties to be certain they are all equal.

It has already been mentioned, but dont you find it strange that so much timing was pulled and it still kept the high knock level? Maybe fuel pressure is something to check.

 

Yeh its very strange... They are FIC injectors and FIC flow test/match their injectors before they send them out.

The only thing I can think of is phantom knock - but I have never seen PK that high... Its a shame I had the radio on coz otherwise I probably would have heard it..

 

You would definitely hear real knock of that magnitude! It might be worthwhile having them checked, but also first check the fuel pressure. Good for peace of mind.

 

Would it be consistant thou? or random?

 

I am pretty sure real knock of that magnitude at WOT would result in a rod through the block.

 

Splash of some race gas would take care of that...

 

think I'd take that bump out of your timing map, and maybe even lower it around 3375, its being held down by the knock isn't it? Otherwise your timing would climb up without the dip?
See how around 4k its dropped down, I'd smooth it so once it starts up it continues up without backtracking. In your case that may mean starting lower.

the big episode of knock might have been a combination of issues, sort of a perfect storm. One thing I think most people will agree on it isn't from your afr- If your afr is correct.

 

3500 11.9

I think that lean spike is what it set off and your tune being aggressive for the mods/boost/octane is what let it get out of control. If you're having that much problem with a single pull try a track day.

 

3500/11.9 yeah :P hehe

For the track I run 19psi flat...

The problem with timing is because the load is going up and down it hits different timing cells, my map is pretty smooth, I guess I could reduce timing in the lower loads so that its more "block" timing, hrmm yuck

 

the reason I suggested your tune is aggressive is because normally if you get some low rpm knock it will diminish yet yours sky rocketed. just because you run low boost that doesn't mean you're any safer.