ECMlink Knock at consistent boost/rpm

[mitsumike0]

Good afternoon all. Recently I've developed a very strange knock problem with my car. I got recently got finished doing my power pulls in my car. We ended at around 26/27 psi. Car did not knock at all during these pulls. Fast forward a week past that, I decide to do another wot pull. I knock 4 degrees at 4k at around 23psi.
I thought maybe I got some gas the car didn't like. So I fill up and do another pull, still knock at the same rpm and boost level. I talked to the tuner, he sends me another map with less aggressive timing. I do another pull and I knock again. So maybe it's the knock sensor. I buy a brand new oem one, install it and I knock again. I then proceed to turn the boost down one complete rotation on my hallman, and still I'm knocking.
I did a BLT this morning and found that my coupler right before my gm maf was leaking pretty bad even at 10psi. I tighten that up and that stopped leaking. Next was my TB biss screw is leaking which I might just do a total tb rebuild. Tomorrow I will report back with a compression test but does anyone have any idea on what my knock can be? When I get home from work tonight I will upload some logs both with more/less timing. Thanks all

 

[mitsumike0]

So i uploaded my logs so you guys can take a look. The first one is another one i did tonight. Tightened up that leaky coupler. Anyone?

 

[boostdawd]

Not an expert tuner by any means so take my advice as such. I would try to richen up in the areas where u see knock and see if it is affected. If knock is consistent in that rpm and u get the same count then it's prbly real knock. Check your spark plugs and verify the gap. Does your car stumble when wot?

 

[mitsumike0]

Spark plugs are gapped at .024 and are bpr7es brand new for the most recent pull. No stumble, nice and smooth transition when build building boost during wot

 

[boostdawd]

I don't have access to my laptop at the moment. Where are your afr's at when knock occurs?

 

[mitsumike0]

On all the logs I posted, knock occurs when afrs are between 10.6-11.1

 

[miliman13]

i know very little, but i want to try to help since any thread with the [ecmlink] icon goes mostly ignored on this site..... its like they want you to figured out yourself.. Spartan mentality i suppose.

Any way, your A/F ratio looks good on WOT /100% Throttle. But it looks a little of at cruise, this may be just because of what i have logged and may not actually reflect what you see.

Look at this screen shot. Your knock seems to be partly due to your load and timing. Consider adjusting the load cells were it knocks, reduce timing and see if helps. If so you have a place to start.

This is assuming there are no other variables.

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[mitsumike0]

Gotcha, I'll give it a shot and see what happens. Thanks. I also thought my pcv system being a part of this problem, but that's a whole different discussion

 

[mitsumike0]

For anyone who is curious on the outcome this is what i concluded from my research: Bad gas. Tonight i ended up going to the auto parts store to get an octane booster to see if it really works. I put half the bottle in since i had half tank and i went off. With the more aggressive timing i knocked, not at 4k but more like 6k and 1 degree less then without the octane booster. Boost was a little to high for my liking (27psi) so i uploaded a map with less timing and lowered the boost so it peaked at 25 psi instead. All i had was a blimp of knock over 2 degrees at 6k then the CEL went away so i didnt let off. Everything else was under 2 degrees. Shifted to 4th and no knock. So for everyone that say octane booster do nothing, now there is proof that they do something. Since the tune is so sensitive i might have to put it in everytime i fill up, but i'd rather foul my plugs (if it does) then blow my motor from knock any day of the week.

 

[boostdawd]

Did u ever try to lower the afr a few down? say u have it at 11.1 drop it down to 10.8. You can also try to put high octane fuel like race gas or even a bit of e85

 

[DsmDanielson]

Yeah you should be able to drive your car without putting octane booster in it. In Az, the highest ive seen was 91 octane and its always hot here, and my car doesnt knock. You know your dsm better than me, but it seems your covering up a potential issue by using octane booster. Like my buddy Boostdawd said, Add fuel where you're knocking and see if that helps. If not, you may have an underlying issue that needs to be addressed.

 

[mitsumike0]

At wot where I saw that blimp of knock at 6k I was already at 10.9 afr. Any more rich and I would feel if I would get rich knock

 

[Kapok6]

At wot where I saw that blimp of knock at 6k I was already at 10.9 afr. Any more rich and I would feel if I would get rich knock

Only way to know is to find out. I have to run 9.5-10 on my car right now (e85) to keep knock away when all my previous motors like 11.5-12.

 

[mitsumike0]

Woah that's super rich with E85. I'll try to richen up the area and see what happens. I'll also see if I can get 5 gallons of race gas to see if this is really the problem. My brother had issues with pump when he was on his 50 trim as well. Not always but from time to time, the gas isn't always the same

 

[DsmDanielson]

It is a change in season so thats a possibility. However, i know people running afrs in the 9's without knock. In fact, i believe either the 1g or 2g dsm stock at wot is something like 9:5:1 so i doubt you will get rich knock by going in the low 10's

 

[miliman13]

sometimes there such a thing as bad gas, experienced it today on my daily.