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Why knock at the top of 3rd with only 8 degrees of timing?
I turned down the boost and did a log. FP red dbb, all bolt ons and hks 272 cams. This is on 93 octane and boost isn't very high and the car is fairly rich it seems. Why am I still getting knock at the top of 3rd? Car just doesn't feel strong. There are no boost leaks. Sorry I don't know how to post the whole log so its a screenshot. 25 psi, timing drops from 8 to 7 when it sees 3 counts of knock.
You need to freeze the label row. But, I'll guess that J is knock sum, and K is knock voltage. It looks like it may be phantom. Does it do it in 4th?
You can post the whole log by attaching the file.
It did not do it in 4th and 4th also seems like it's a bit richer up top. You are right about "J" and "K" ... what can I do to make sure it's phantom knock / get rid of it?
You need to find the phantom knock or you'll just keep pulling timing. I don't suggest tuning out the knock either. Check your engine bay, exhaust hitting anything? Loose intercooler pipes....etc
It did not do it in 4th and 4th also seems like it's a bit richer up top. You are right about "J" and "K" ... what can I do to make sure it's phantom knock / get rid of it?
Is L your AFR? If it is it looks fine.
Easiest way to tell if the knock is phantom is leave the tune alone, and add about 5 gallons of 100 octane to whatever fuel is in the tank. If the knock stays with the extra octane, it's very likely phantom.
Also, you should be able to run more timing than that. I think my car runs 9* or 10* out the top with 25psi on ACN 91.
If physical timing is good and if the engine has good compression then why not go to a dyno?
I would spend an hour on a dyno jet and adjust the tune . You will be able to see and hear exactly whats going on instead of countless road pulls . The graph will show how well or poorly the engine is running.
A hundred bucks is cheap compared to hammering the bearings out of something or another problem.
If you have E85 available then you could also schedule some time and tune the pump and E85. Call me conservative but I never ran much boost on pump gas when ethanol is much safer.
Is your rpm limit set to 7200? I find that hitting the limiter sometimes give a false knock scenario due to the engine harmonics. Raise the limit to 7500 and do a pull to 7200 and see if it still happens. Also drop the boost down a little . See if it goes away then you would know you are on the limit of octane for your setup. Good luck!
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Jun 22, 2016, 09:53 AM
