Positive knock

[Dosia]

After seeing positive knock on 91 gas here in AZ I decided to go the E85 route. Unfortunately my knock readings are still positive (typically around 1-2 degrees from 5k to 7k). Is this actually an issue now that I have better gas. I have checked my catback exhaust and it has zero clearance issues and it is nice and tight. I am really running out of things to look at here. If this is truly "false knock" am I at any risk of egine damage or just power loss?

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[dev1360]

What's your total timing at?

 

[Dosia]

Sorry I am a complete noob. What parameter do I look at to see that?

 

[mdnt]

spark advance
check what your measured AFR is also

 

[Dosia]

AFR is 0.85. Spark advance is at 32 when adding timing and drops to 22 when pulling when knock jumps up to 1.94.

 

[Dosia]

 

[mdnt]

timing curve too agressive, do you have a aftermarket CAI/mass air? if so your mass air looad curve might be off

 

[Dosia]

timing curve too agressive, do you have a aftermarket CAI/mass air? if so your mass air looad curve might be off

Nope just stock intake.

 

[mdnt]

try dropping the timing 2* see if it responds

 

[Dosia]

Thx. Shaun is tuning it so Im sure he will dial it in. Im just trying to understand this data a bit more so I can have a clue on whats going on.

 

[mdnt]

hptuners.com forums great place to read in spare time to learn the general stuff


https://www.motorcraftservice.com/FreeResources/OBD for Ford general EFI understanding

 

[Jeff_oddo]

I just did a datalog on 93 and I am seeing .223 - .670 positive knock from 5900-7200 rpm. Waiting to hear back from Lund on it.

 

[Screwdgie]

I just did a datalog on 93 and I am seeing .223 - .670 positive knock from 5900-7200 rpm. Waiting to hear back from Lund on it.

I see roughly the same and Lund says it is fine and that the knock sensors are doing their job. Obviously I'd prefer none lol

 

[mdnt]

ive seen stock tune do 1-1.5 positive, the adaptive has to learn its limits

 

[Choking_Victim]

Pretty common on 91 in az it pretty shitty...mine will go away on e85 or a blend there of.

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