I get crazy KR on cylinder 4 when datalogging. No other cylinder sees knock, makes me feel like its false. Anyways check this out: http://www.hptuners.com/forum/showthread.php?t=30115

 

bump...

 

Interesting info. I've noticed that I get tip-in knock, but once I'm at WOT, it goes back to 0.

 

the lnf does that. it has knock from factory on light acceleration, it goes away at wot or even harder throttle. I had a bit at wot in this warmer weather so i started using 94 octane and it went away.

 

heres a picture that Stamina took of his motor, when his piston gave up. look at the knock sensor to the right (cyl. 3 and 4), its pointing at about 5 oclock. So far it seems that 9oclock is the best position for the pigtail to point. GM states 90* from vertical, but the gm tech on hpt forums is saying 9oclock. This could be the culprit.

 

Are these sensors directionals anyway? From what I know, they only transform vibrations into a voltage and are made from cylindrical parts, so the clocking shouldn't matters. Since the ecm knows which cylinder is in the compression then combustion stroke, it can determine which cylinder is knocking.

Here is a quick read about bosch knock sensors. I don't know if our cars are using bosch sensors, but since it use a bosch engine management I think it's a good guess.
http://www.bosch.com.au/content/lang...sors_knock.pdf

 

check the link in the first post. The gm tech also said that they should be uni-directional, but that the procedure says to position them 90* from vertical, so either 3 or 9oclock. However so far he is having the most luck putting that at 9oclock.

 

One way to rule out false knock is to get your hands on some high-octane fuel. If it reduces the knock, then it probably isn't false.

 

I have checked the link, but all the ''sensor clocking'' he did is pretty much aleatory. It's hard to correlate any changes to a result with these kinds of tests. And with how these sensors are made, it's not logical for them to behave like that, but who knows. It's the bolt that is holding them that transfers any vibrations to the sensors, but maybe the wire is causing some kind of resistance or binding of the internal mechanism in some positions? Other than that I don't know. It's still possible though...

 

Well if the sensor isn't actual uni-directional or more sensitive depending on the degree the pigtail is pointed would/could cause false KR to be picked up. Right now this is just a theory but showing good results.....

 

interesting, guy may be onto something

 

isnt 9oclock 90 degree from vertical? so gm and the tech are saying the same thing.

 

ummmmm, you musta missed it. Look at the picture above. No one ever argued that the tech and GM said different things. the "argument" is that the knock sensor for cylinders 3 and 4 is not 90* from vertical, which means 3oclock or 9 oclock. The GM tech says 9 oclock has been more promising vs. 3 oclock.

 

ahhh i see now. im gonna check mine

 

Question. Can you actually hear the pinging/knock or just from what your gauge/datalog tells you? I can hear it pings at tip-in as well and I don't have no factory digital pillar gauge or datalog. All in the ears.

 

Nope, no audible ping at all. I would be seriously scared if I could hear audible ping on a modern engine. Like would not drive it anymore, until I found the root cause.

 

X2... no bueno