False knock, now what?

[juyanith]

Okay, I think I have an issue with false knock. Here's the details: The car was tuned elsewhere and I noticed that the tuner rather aggressively turned down the various knock parameters. (Probably because of this.) However, it looked to me like it was too much so I figured I'd set things back to stock and see for myself. After I saw the consistent knock, I put the stock timing tables back in and pulled 2 to 6* to see if it would go away. Well, if you look at the attached graph, it didn't.

So, what are my options?

1) I know to check the exhaust, but I have already done this because it was making contact with the car constantly. It doesn't do that anymore but I will check it again.

2) Replace the knock sensor. Well, I suppose I can but do I really have an indication of failure or am I just replacing parts and hoping? Are there other mechanical issues to check? As far as I can tell the headers are not hitting anything.

3) Make the knock parameters less sensitive. What would be good choices without causing the car to ignore real knock, if any? I don't mind if it occasionally pulls a little timing, but right now it's way too much.

Thanks ahead of time.

[deano1712]

I was getting a similar amout of KR with my LS376/480, even with 100+ octain fuel. I have no obvious rattles but a header pipe running very close to one of the knock sensors. I increased the voltage thresholds on the knock sensors and this has stopped the KR. Dont have HPT with me but from memory there were two values - 50mV and 120mV and I increased to 100mV and 200mV respectively. I'm a novice tuner and dont know whether I have done the right thing so interested to hear comments from others on this...

[04colyZQ8]

interested also I have pretty much given up eliminating my 2-11 degrees of knock retard long tube headers and flow-master 40 series . I have retarded the tables at least 18 degrees or more in the trouble spots still get lots of KR??? Must be false??

[Mep_q8]

Looks to me your getting knock before you actually go WOT which would relate to burst knock.. have you disabled the burst knock and tried? try getting those fuel trims inline just before wot so the fueling transition won't take a hit...

I've never seen fuel trims change through a WOT run though? Look at the LTFTs. Get those done then disable burst knock and take another run..