F150 EB

Hoping someone out there has good experience datalogging with SCT...

PID for knock sensor is labeled "knock sensor retard" and displays in degrees.

Common sense would say a negative value means knock was detected and the sensor wants to pull that much timing out, positive value means the sensor tells the truck 'hey, I can take more timing please and perform better'.

I actually called SCT and that's even what THEY told me. I, however can't accept that.

I think it's exactly reversed. A positive value shown when logging knock sensor activity indicates a knock event and that value is how much the sensor/computer want to retard the timing to avoid continued knock/detonation.

I validate this because every tune I log shows the knock sensor going to a positive value (let's say 3* to 4*) and the timing (spark advance) is simultaneously decreased. So it seems that when the knock sensor log is displaying a positive value it's actually telling the truck to pull timing.

Anyone confirm this or tell me I'm a retard? Either works!

geno51

I have logged and been with tuners while they were logging and making adjustments and you are 100% correct a positive value is the amount of timing being pulled! And completely ignore the negative value.

Hope that helps

F150 EB

Thanks, had a feeling you'd be chiming in pretty quick

What this does mean is I've got a f'n problem! I have not run a single person's 93 performance tune that doesn't knock like a ****.

I guess the only common denominator is where I always get gas. I'm gonna run the tank all the way down on stock tune, put in 10 gal of race gas and see if that sensor stays at zero or less.

geno51

A little knock is ok the question is how much are you seeing and when? I have had 2 tuners Datalog my truck and neither were worried about a little knock. 6* is the most I have ever seen under super high load like 4wd boost launch and 4gear lugging high boost up a hill. Torrie actually added boost even seeing 3-4* of knock. The problem is knock under load high rev and more then the truck can pull that's what will get you in trouble. Send me a snap shot of your log where it's knocking and I can tell you how it compares to my logs. I can say dealing with full races tuner he made some good points to pick up some over all power by pulling timing or boost under certain cases to pick up power. We did see improvements

engineermike

Great thread! I really wish my scan gauge would read knock retard. I've even tried programming in x gauges and no luck.

Will one of you so me a huge favor??? Settle the debate by putting 87 in the tank, drive around at part throttle, and tell me if its pulling timing during cruise and mild acceleration.

geno51

I was talking to miller on the phone hes got some bigger issues he sent me a video his truck is knocking like nothing I have ever seen

As for me I know for a fact mine is only knocking under the most extreme loads and cases and its only pulling a little timing nothing like Miller is seeing

Geoffs tunner has got me dialed in! Just so you guys know there is some real cool stuff coming with their tuning like no one else has done yet

F150 EB

Geno - Funny thing is, when I look at the log of that video the knock sensor PID only reads a max of 3.5*, and that noise is still being made.

Looking at logs of ALL the tunes I have, they ALL have positive knock sensor values during a 3rd gear WOT pull on the street, ranging from 3.5* all the way to 10*.

Last car I logged and tuned was a turbo mustang, and if knock sensors pulled anything over 1* I was concerned. So seeing this much on this truck concerns me.

CoreyMS

Send it to me, I wanna see

F150 EB

PM'd you

geno51

Miller I really think its the wastegates from our talks But regardless I know that they will get you dialed in

My official guess is a bad waistgate actuator causing what you showed me in that text its fine under normal boost but that tune is just to much for it causing it to flutter.. Thats my guess and I want a cookie if I am right