positive knock at WOT

[codemanstang]

Hi guys

Lund Tune, at wot i get about 2.65 positive knock. Dont think ive seen it over this. I will admit i have small leak from my h pipe clamps. But is this enough to worry about to not go drive it through the canyons? I sent them to Lund but wont be until monday when they get back to me. I have log file, no idea how to upload them here lol

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[BMill705]

An exhaust leak can definitely cause positive knock so that may be what's causing it. I would say your ok until they look over your logs, 2 degrees of knock really isn't that much. Before I fixed my false knock and bad gas issues I drove over a year with 3+ lol.

 

[codemanstang]

An exhaust leak can definitely cause positive knock so that may be what's causing it. I would say your ok until they look over your logs, 2 degrees of knock really isn't that much. Before I fixed my false knock and bad gas issues I drove over a year with 3+ lol.

Haha thanks man I appreciate the info that makes me feel a bit better :cheers:

 

[dubster99]

An exhaust leak can definitely cause positive knock so that may be what's causing it. I would say your ok until they look over your logs, 2 degrees of knock really isn't that much. Before I fixed my false knock and bad gas issues I drove over a year with 3+ lol.

How is an exhaust leak at the h pipe causing positive knock? Doesn't make sense to me. That means everybody running race exhaust off the header leads would be seeing positive knock right?

There's either something wrong with your tune, gas, or knock is false. If you want to know what it is, dump a can of torco/VP octanium in your tank and see if the knock goes away. How much timing is it seeing at WOT, and what fuel are you on?

 

[Tommy V]

How is an exhaust leak at the h pipe causing positive knock? Doesn't make sense to me. That means everybody running race exhaust off the header leads would be seeing positive knock right?

There's either something wrong with your tune, gas, or knock is false. If you want to know what it is, dump a can of torco/VP octanium in your tank and see if the knock goes away. How much timing is it seeing at WOT, and what fuel are you on?

Agreed a exhaust leak is not going to cause false knock,I also would not drive my car around for a year knowing at wot I'm getting 3 degrees of knock,geeze some of the comments on here

 

[dubster99]

Agreed a exhaust leak is not going to cause false knock,I also would not drive my car around for a year knowing at wot I'm getting 3 degrees of knock,geeze some of the comments on here

Agreed...not smart at all.

 

[3beeps]

Asking this question here is futile. Lund will help you figure it out.

 

[BMill705]

Ask any tuner and they will agree an exhaust leak can cause false knock readings. I know for a fact because I I had a leak and once fixed it corrected my knock readings on the same tank of gas.

 

[BMill705]

I trust my tuner enough to know that when my logs are looking perfect other than the suspected false knock readings I'm not too worried about it. Over time I did find the cause of the false knock. Do a little reading and you will see there are many people driving around with the same issue some even on stock tunes.

Agreed a exhaust leak is not going to cause false knock,I also would not drive my car around for a year knowing at wot I'm getting 3 degrees of knock,geeze some of the comments on here

 

[dubster99]

Ask any tuner and they will agree an exhaust leak can cause false knock readings. I know for a fact because I I had a leak and once fixed it corrected my knock readings on the same tank of gas.

You sure that wasn't just loose exhaust clanking together? Air simply leaving a leak in the exhaust won't cause knock. False knock sure, if the exhaust is loose and banging together.

 

[BMill705]

It was a small leak at the weld, was loud enough to hear on a cold start.

You sure that wasn't just loose exhaust clanking together? Air simply leaving a leak in the exhaust won't cause knock. False knock sure, if the exhaust is loose and banging together.

 

[BMill705]

Also comparing a small exhaust leak and an open race header are two entirely different things. If you ever heard an exhaust leak you would understand. Some can be mistaken for a loud ticking sound depending on the size of the leak.

 

[dubster99]

I stand by my statement that air simply escaping the system does not cause knock. Now if you have loose/damaged exhaust that is rattling/banging/etc, the knock sensors will pick that up. The knock sensors have no idea where air is going, doesn't matter if it's escaping through a leak or out the back of the exhaust.

 

[codemanstang]

This is my first aftermarket tune soon I'm total newb to all this. I do know negative and.positive knock. I filled up at another chevron 91 octane 30 miles from my normal gas stations and am.now seeing 3.62 knock. Might avoid that station in the future. I'll pull my.logs when I get home and upload the timing result at WOT. Sent logs to lund may snot hear back until some time Monday

 

[dubster99]

Throw some octane booster in it and see if the knock goes away. If it does, you have actual knock. If not, you have false knock.

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