I'm sure this is not your problem, but it was a problem on my IX. I was getting phantom knock that eventually lead to a Knock Sensor Failure code. I purchased a new one and when replacing the old with the new, I found the old sensor was lose, I could remove it with just my fingers. Nothing was ever touched back there, this was from the factory. I replaced it with the new one anyways and never had a problem since. I've re-tuned twice since then on a dynojet, on 91oct and now E85, with no more phantom knock. Since this a real pain in the *** to get to, I'm not sure how many have checked there KS.

 

oh yeah.. sorry I run about 11.0 AFR as well, rather than 11.7.

Still I am still a bit shocked that 12.0 AFR is "right on the edge".

 

boost/afr/timing all hinge on one another so yes, 12.0 afr can be acceptable if the boost/timing is reasonable. You really cant talk about one without the others.

 

ill tell you i had something like this occur to me the other night, it was rather cold, i was adjusting my tune for my cams, at 25psi on a 4th gear pull i audibly herd knock, i had been watching my laptop and saw the graph shoot up so i lifted, ended up at 26 counts!, i checked my fuel and timing...added maybe .2-.3 in fuel and pulled 1* where the knock started...it then went to 2 counts...couldnt explain it, havnt seen that kinda knock since, it was pretty random since a previous 4th gear pull had 6 counts idk how it got so high.....

crazy stuff

 

I did a few pulls when i first started tuning at 12+ AFRs. I never had knock but EGTs were a bit spicy. Timing wasnt ultra conservative either even with 22psi.

 

But had you ever run the AFR that lean?

What I was trying to point out was that there there appear to be some combinations of timing/AFR/boost that lead to unpredictable response (sometimes 0 knock, other times massive knock), at least in my experience. But of course it could be one of the other possibilities that people mentioned.

 

mmmm I just guess i expected the KS to be linear...

 

12.5 - 13.0 AFR WOT (30psi peak, 7 - 15 degrees spark, intake cam retarded 2 degrees) works fine for me, but with methanol inj. 1-2 counts on occassion, richer causes knock.

 

just a little update on this.

I am leaning towards a problem with 1 injector (or connection).

Sometimes I can do a 3rd/4th gear pull without any knock and then othertimes I will get 8/14/36. I have audibly heard a "ping or tink/tink" so it must be real knock.

Now I figured the LC1 wouldn't show a lean condition if a single injector was faulty, ie: if the cylinders are 13/11.5/11.5/11.5 the avg is 11.9... I have contacted Jens(FIC) for some advice - but I am tempted to re-seat them just incase...

Either way I have pulled 3* in my WOT areas and will resume logging tomorrow. I also want to get under the car to dbl check the frontpipe (down pipe) isn't clunking on anything

EDIT: Surely if one of the injectors had a problem then it would show up all the time, not just intermittently - UNLESS it was a faulty connector???

 

im having a similar prob , il get a clean 3rd gear pull a few mins later up to 14 counts, also leaning towards injectors /leaking as i get similar to a backfire more like a pop in inlet maniflod on cold start .

 

I've only got UEGO experience but when my sensor failed it failed reading lean. Didn't matter what I changed A/F wise when I went WOT it showed around 12.8 -13 :1. Might be that yours is failing and just returning a bogus A/F

 

you could always physically check whats happening in the cylinders!
take out the spark plugs and inspect them, its possible the cylinder that is playing up will show on the plug or if its all cylinders the spark plugs will tell the story.

 

yeah we pulled the plugs on Friday - not much going on there...

edit - I also see a lot of black smoke when doing a pull - So I think the LC1 is ok

I am tempted to swap back to stock injectors just to see if that fixes it... But then I will have a set of injectors that "could" be faulty..

 

i changed injectors still same prob .

 

tephra it might be wise to ship them off to be cleaned and flow tested...it can be a real eye opener sometimes.