Knock Sensor Activity

[gtmiller1001]

Let's call this a hypothetical question for now....

2011 GT w/forced induction, that's it.

Dyno pull in 5th

Knock sensor kicks in and pulls EXACTLY 1.5* at 4,640 RPM

Chokes back to only pulling EXACTLY 1.25* at 5,370 RPM

Chokes back to only pulling EXACTLY 1.00* at 6,050 RPM

Chokes back to only pulling EXACTLY .75* at 6,620 RPM

Timing pulled is in exactly the same increment every time and it's a round number.

IF that's all the info you had, could you make any possible educated inference as to what the tune is doing? I'm not a rocket scientist when it comes to this, is it normal for a knock sensor to pull timing in a round increment (.25*) like that and step back equally?

Seems to me that it could be the sensitivity being messed with, but I don't know...

 

[gtmiller1001]

Anybody?

 

[Swarzkopf]

Looks like you had a knock event at 4640 RPM- the ECM pulled 1.5* of timing to compensate for it.

At higher RPM, I'd think that maybe the knock sensor(s) was just picking up too much engine noise (pretty common for force inducted stuff), but at 4600 RPM, I'm thinking it's real.

There's a "decay" value to knock spark activity, where the spark isn't all put back in after the knock event occurs- it's gradually re-introduced, as bringing full spark back immediately would likely cause another knock event. In your case, the PCM looks like it's bringing .25* of spark back in at specific intervals following the detected knock.

 

[gtmiller1001]

Makes sense, I was curious if they worked that way or if maybe the sensor sensitivity was manipulated. Thanks for the response.

By the way, don't know if anyone has ever logged their stock tune, but I did once upon a time. That thing had timing being pulled all over the place for knock

 

[dysan]

What type of power adder is on the car??? If it's a roots/TVS/twin screw type of blower that mounts to the engine then you will have additional noise which will set off the knock sensors. Mine occurs right around 5000 rpms so Lito set them to not pull timing above 5000 rpms but they are still functional below that.

 

[gtmiller1001]

What type of power adder is on the car??? If it's a roots/TVS/twin screw type of blower that mounts to the engine then you will have additional noise which will set off the knock sensors. Mine occurs right around 5000 rpms so Lito set them to not pull timing above 5000 rpms but they are still functional below that.

Turbo, tuning is still in the works.

As for lowering the sensitivity of the sensors at higher RPM's, what happens when you get some bad gas and the knock they would have picked up above 5K isn't due to excessive noise but true knock??

 

[dysan]

Unfortunately there's not much that can be done about that. I had bad gas on tank and fortunately my engine survived. It scared the shit out of me when I could hear the detonation at the track.

 

[Swarzkopf]

If you want to see if it's "real" or "false" knock, back timing out 2* and re-scan it. If the knock retard is gone, guess what? You fixed it. If it's still there, it's just engine noise being picked up by the knock sensor.

 

[Steedagus]

If you want to see if it's "real" or "false" knock, back timing out 2* and re-scan it. If the knock retard is gone, guess what? You fixed it. If it's still there, it's just engine noise being picked up by the knock sensor.

Thats not necessarily true, to be sure you need to take out more than 2 degrees, I would take out 2 more after the first two. Do it in 2 steps, with 2 degrees at each step, that should tell you for sure.

 

[Seer]

You also have a knock recovery setting as well. How fast you recover from your knock event.

 

[CPRsm]

Looks like you had a knock event at 4640 RPM- the ECM pulled 1.5* of timing to compensate for it.

I agree. Most engines are going to have peak cyl pressure in this area and most likely area to ping.

Run the tank down, throw in a bit of race gas. Check again.

 

[Swarzkopf]

Thats not necessarily true, to be sure you need to take out more than 2 degrees, I would take out 2 more after the first two. Do it in 2 steps, with 2 degrees at each step, that should tell you for sure.

Eh...if the ECM is retarding timing 1.5* due to knock, removing 2* would most likely get rid of it- in my experience, the ECM usually over-compensates a bit, and if you like running a ragged edge tune you'd probably be able to eliminate that 1.5* of ks_spark with 1* of removed timing in your tune. That said, point taken- or putting race gas in like CPRsm may be a better test still.

 

[Nastystang06]

Does anyone know how the sensors work on the 93 lund cammed tune for a 5.0

I popped #8... broken ringland
I don't want to repeat this but I would like to figure out what made it do this
And I want to monitor the cannedI 91 tune on the screen to see if that one is safer

Jlt and exhaust is all I have

I wonder if the knock sensors were even on in the cammed tune

And if the sct tune adjusts them

 

[Seer]

Lund states he leaves the sensitivity of the knock sensor to stock value.

 

[RazorbackMustang]

I agree. Most engines are going to have peak cyl pressure in this area and most likely area to ping.

Run the tank down, throw in a bit of race gas. Check again.

I think this is a good idea. Change one variable at a time. This will definitely tell you if it's real of just noise.

 

[Nastystang06]

Lund states he leaves the sensitivity of the knock sensor to stock value.

If that's the case I should be able to run the same tune

Its a "LUND" tune It but I bought it from evolution...

 

[Seer]

If that's the case I should be able to run the same tune

Its a "LUND" tune It but I bought it from evolution...

I heard somewhere that not all Evo tunes are Lunds anymore.

 

[Nastystang06]

I heard somewhere that not all Evo tunes are Lunds anymore.

Before I purchased it I called and it was guaranteed safe
And also it was supposed to be a lund tune...

I wonder what actually got it...