I got the knocks: Please Comment

**ojmcneill** · 05-04-2012, 08:33 AM

What's up everyone. I;'ve gotten my trinity and I've becoem somewhat proficient with it other than wot fuel and timing. How do you know which way to go. I've data logged and am seeing a max of stkr of 6 and sometimes ltkr of 1-2. I've added 3/5/5 for the rpm ranges and I added 5/8/8 on the rpm ranges. Didn't seem to make a dent. I'm running a catch can, bp gas and everything else I can think of. Innitially it was worse bc I was running shell friggin slosh gas. Anyway, so I should be going to the left to the rich side, correct? What am I missing here.
OJM

**aim4squirrels** · 05-04-2012, 09:28 AM

Can't help you but i am definitely interested in the possible solution as well.

I've gone up to as much as 10%, 15%, 15% with no reduction in knock past about a 3% fuel addition.

I've often wondered if part of the magic of a custom tune is really addition by subtraction. I can't believe that every station I've tried has bad gas.

Additional power added by subtracting timing in critical areas of the rpm range to get rid of the knock retard.

**ojmcneill** · 05-04-2012, 10:49 AM

See I thought I was supposed to add fuel for knock, but when I did, the knock just went down maybe a little bit and I felt like my power went down noticeably. Would adding fuel reduce your power? Thats kinda counterintuitive isn't it?

**bipto** · 05-04-2012, 10:54 AM

Interested in this discussion as well. Maybe some of the folks here who went to high school with Jesus will weigh in...

**Gdragich** · 05-04-2012, 11:40 AM

Can be other things like mechanical causing the knk. You can add some fuel to try and quiet the knk from too lean af, but if not working you probably need to dial back timing a degree or two (retard timing or negative on predator). The CMR tuner can look at all the parameters from the logs to adjust air fuel tables much more precisely which is the better alternative to just making some fuel adjustments at rpm bands in pred. I've used to to just try and the af back when too lean to get in the ballpark on the log and send tune back for revision.

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**aim4squirrels** · 05-04-2012, 12:32 PM

I do know that going too rich will cost you power as well. That is why I dialed it back as much as possible after I went that extremely rich. If it wasn't reducing knock, it's wasted fuel and lost power. Gotta have enough air in the mix to oxidize the fuel. I believe extra fuel can be used for a cooling effect up to a point, but you also have to worry about working the cats over as well with too much fuel.

Anybody know how much timing difference there is between the 91 and 93 octane tunes?

**whitehemi** · 05-04-2012, 12:39 PM

I have tried the 93 tune multiple times only to see power and et's drop from using the 91 CAI tune.

**Gdragich** · 05-04-2012, 03:42 PM

(3 is same as 91, but with a little more timing at points. Reason some actually have slower times is the KNK and the pcm pulling timing that nets lower than just running the 91 with no KNK.

**ojmcneill** · 05-04-2012, 03:54 PM

Bipto, did you cheat off jesus in math class?

**TanT** · 05-04-2012, 04:35 PM

First you have to identify why and where (RPM range) you are getting knock. Knock retard can come from a lot of different variable. It can be broke down into 3 basic categories, actual knock, and false or ghost knock, or a combo of the two.

Actual knock (pre ignition) aka detonation, can come from a lean AFR condition at a given RPM range, incorrect octane rating for given amount of timing at a RPM range, timing advance to high at a given RPM range, or a combination thereof. "Bad" fuel or excessive oil in the combustion chamber will also cause actual knock.
You shouldn't be running peak timing advance higher than about 23-25 degrees, and should be lower, lower in the RPM range. All the while watching AFR and seeing 12.0-12.5 (N/A) throughout the pull. If your tune is meeting those parameters, you could be getting false knock.

False knock can be caused by a great assortment of things, be it a part of the exhaust system chattering on the undercarriage, knock sensor bolt out of torque spec. (to tight or to loose), "loud" valve train noise for whatever reason, tranny inspection plate loose or missing foam cushion, bad motor mounts causing noise or the engine being able to torque to much and cause header contact or something else, etc, etc...List is damn near endless, real PITA to hunt it down, and can be 1 thing or a combo of all of them, like I said, a real PITA.

Certain combinations of stokers can experience false knock from sensor sensitivity being set to high in the tune, and all other parameters in the tune being spot on. In this case, a qualified CMR tuner will have to do the adjustments.

First identify if you do have real knock or false, identify the cause of it, and repair the situation, or adjust tune. I would start by making sure your AFR is in check, then remove timing and log. If it reduces by the same amount, or their about, you at least know you have some real knock.

Good luck with tracking it down.

**Big Boy** · 05-04-2012, 05:24 PM

Maybe you should back off on the timing. I don't spend as much time with fuel as I do with timing.

But if this is something brand new you might have some other problems.