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Discussion Starter #1
I am performing a Lund tune on my MK4 Coyote build. I have a 2017 Gen2 Coyote crate motor, FFR headers/side pipes, and TKO 600 transmission. My tuner never mentioned any issue with knock on my data logs until my R3 WOT data log session.

For my R2 (second revision) I performed a WOT from 2500 - 7200 rpm and my data log shows only negative values for knock, ranging from -0.5 to -1.859 throughout the RPM range.

For my R3 (third revision), WOT shows a positive knock range of 0.094 to 6.799 throughout the RPM range.

At the tuners suggestion, I added some VP Octanium and logged another WOT. This time it recorded positive knock range of 0.063 to 1.355 throughout the RPM range - significantly less than the previous run but still present. The tuner then told me since it was still there he believes it is false knock and I should see if I can find the source.

I trust the tuner but thought I would ask for advice here as well. I know for a fact that my drivers side header is hitting the footbox, it's just so tight with the Coyote I think this is probably common for others. Since I didn't see any knock before the R3 tune I wonder if something could have come loose. Any ideas where else to look? Also, the tuner says he didn't change anything between R2 (no knock present) and R3 that would affect the knock. I have only used 93 octane from the start, but did fill up from a different gas station between R2 and R3. My thought are that since it did improve after adding Octanium, perhaps it is bad fuel? Or maybe something came loose between R2 and R3. I'm not really sure where to start looking. Advice?
 

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I think what you are calling knock is ignition knock retard. I have not dealt with this in a while, but I think + ignition knock numbers are reducing timing, and - add timing. You might want to verify this.
My tune was a Lund, run on a local dyno. I also had timing retard due to knock. My advisor told me it was probably gasoline related.
I checked the hood prop rod, the cold air tube, exhaust pipes and etc for something that might give a false knock reading.
I added about 1/4 of a can of Torco to the tank for my second visit, no knock, seems like it might have added marginal timing.
Lund commented on my data log, that the knock had disappeared.
The gas we buy at the pumps is junk. I have run some VP and Sunoco canned gas and the difference is unreal.
Ignition knock retard is not harmful to the engine. It is the computer adjusting the timing for the quality of gasoline you are running, or anything else that will cause combustion chamber knock.
Your computer is adaptive and will adj with in the range for it.
Tune it on pump gas and if you want to run some good stuff, it will reward you.
 

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Well... It could be either. Actual pre-ignition knock or mechanical or "false" knock. The knock sensors are so sensitive in these engines that it can detect either. What you don't want is the PCM reacting to "false" knock. That's the point of the Octanium (or other octane boosting additives) to see how that affects the reading, and to determine if false knock or not. I went through this exact scenario with Lund while helping to tune a buddies non-FFR Coyote powered Roadster. They know and understand this. We were able to determine it was false knock and we didn't do anything further which Lund agreed with. In that case, it was a very mild reading. I don't know about yours, but if Lund says it needs to be addressed, I'd try to find what it is. If you have a header hitting the footbox, pretty good chance that's what it is. A WOT run could certainly uncover it. From what I understand, doesn't take much.
 

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Discussion Starter #4
I'll get the car up on the jacks and look it over. I just find it very odd that if it is the header hitting the footbox, why it only appeared between R2 and R3. The engine position on the mounts has not changed.
 

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Not sure what Lund uses but can't you print out a graph of the log. That would clearly show a timing or fuel pull. This is one on my old ones on a different car when I was beta testing some Burger Motor Sports tunes for the JB4 system on BMW's. Ran the 100 octane map on 94 octane in this one.

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