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phantom knock! or real knock?

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Old Jan 26, 2011, 06:16 PM   #16
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What do your sparks plugs look like?

I would think if the car has been driven like this for a while...Really knocking this much consistantly then the plugs should totally show it.


Black specks or silver specks?

If the plugs look fine...light grey, tan or any kind of off white without a bunch of black dots on them...I would say it's not real. Of course the problem still need to be diagnosed if it's keeping you from being able to tune the car.

Good luck man
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Old Jan 26, 2011, 06:37 PM   #17
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I had a similar problem since switching to Kelford 272's, and, ironically, I first noticed it while trying to get tuned at CBRD.

I checked all the culprits already listed and ended up just running my fuel tank almost empty and dumping in a 5 gallon can of 110 octane. The knock numbers didn't budge, so I felt confident it was phantom knock. I then adjusted my knock tables a little at a time, until I only got a 1 or 2 count here and there. Then I emptied it and put 93 back in to datalog and make sure I didn't get any knock again. Seemed to work for me.
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Old Jan 27, 2011, 02:42 PM   #18
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yeah its typical to see some light load noise with some of the cams, but pinning the knock sensor at 36... not normal!

I always recommend valve springs on anything other than something like an S1 cam!

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Old Jan 27, 2011, 04:14 PM   #19
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my guess is just that it is valve train noise i replaced the knock sensor still the same result. thanks for the help guys. spark plugs are new an the old one looked normal a little rich since its not tuned an it dumping fuel lol
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Old Feb 6, 2011, 02:51 PM   #20
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subscribing. I'm running stock cams, ams TBE with a dynomax VT muffler welded on the end. I self tune and have been getting knock occasionally during free rev and low loads/low RPM. When I do a full 3rd gear pull I'll get an occasional 1-2 count in areas but not consistent. I'm thinking I have phantom knock or mechanical noise causing the knock. Is the best way to check if it's phantom knock to dump some race fuel in and try to duplicate knock (i.e. free rev and low load/rpm)?
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Old Feb 6, 2011, 03:36 PM   #21
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Quote:
Originally Posted by MR White View Post
subscribing. I'm running stock cams, ams TBE with a dynomax VT muffler welded on the end. I self tune and have been getting knock occasionally during free rev and low loads/low RPM. When I do a full 3rd gear pull I'll get an occasional 1-2 count in areas but not consistent. I'm thinking I have phantom knock or mechanical noise causing the knock. Is the best way to check if it's phantom knock to dump some race fuel in and try to duplicate knock (i.e. free rev and low load/rpm)?
if its off and on 1-2 counts etc.. make sure its not occurring in areas on the map where the RPM axis skips a certain amount of RPMS and your jump in timing isnt to much to compensate inbetween those 2 RPM columns.

example: we have a car that wants 8* only at 6800rpm but on our rpm axis on the map we have 6750 and 7000 only..

you have 6750 set to 8* and 7000 set to 10*, because the car actually does want 10* at 7k .. but then you have an issue, because if youre trying to not hit past 8* at 6800 and targetting 7k for 10 the ecu is going to jump and increase timing to hit that 10* at 7k causing real knock because of the random 9* at 6800.. the car may give 1-2 counts of knock due to the fact its trying to hit 8* at 6750 then follow through to higher timing to get to the 7k target.. creating an occasional 1-2 count knock which would be real in this case.

so what im trying to say is pay attention to your RPM Axis and scale it smart.

thats one example where you can have real knock but only occur off and on.
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Old Feb 9, 2011, 02:12 PM   #22
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Tscompusa, I think that is my issue. Just pulled some logs and at 3500 my car is ok with 3* and at 4000 I have it set to 4*. At 3600 the car wants 3* but it's shooting for 4 and causing intermittent knock. How do I rescale the rpm axis?
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Old Feb 9, 2011, 02:21 PM   #23
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you may want to degree the cams in to make sure they are dead on. i have heard many stories about the BC cams being way off as far as timing goes.
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boost, cams, cosworth, evo, evolutionm, free, gasket, head, kelford, knock, leak, load, low, phantom, rev, symptoms

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