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Old 01-07-2014, 06:57 PM   #1
leforce
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Angry Stubborn knock

I've been getting this constant knock readings between 5000-6000rpm, boost is around 16psi, AFR @ 11. fuel 93oct. The symptoms: first, IAM would drop to 14 & in some cases to 12 & then I'd get FBKC -2.11, -4.22, & some times -6.33. I know that the readings are real knock because it was audible without det cans.
Naturally, I gradually reduced timing in knock areas, but knock didn't totally disappear until I reduced an average of 15 degrees of timing down from the original rom! Now the timing table looks ridiculous!
Such high, persistent knock wasn't normal to begin with on a stock rom & a moderate level of boost, so I wonder would be causing such knock, what should I look for?

The car is a 2002 JDM STi EJ207
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Old 01-07-2014, 07:12 PM   #2
ProfessWRX
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what should I look for?
False knock.
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Old 01-07-2014, 07:31 PM   #3
leforce
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False knock.
No, I mentioned it was audible, I could hear it, it's loud & clear

Last edited by leforce; 01-09-2014 at 05:16 PM.
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Old 01-07-2014, 08:56 PM   #4
rexworx
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Have you tried giving more fuel in these areas?
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Old 01-07-2014, 11:44 PM   #5
leforce
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yes I did! I managed to 99% eliminate the knock, but that's not the point! I shouldn't have such high knock with a stock rom, normal boost to begin with, the amount to timing reduced to eliminate the knock (-15) is simply too much!
I'm suspecting that something other than the rom/map is inducing such knock, perhaps an electrical issue.
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Old 01-09-2014, 01:13 PM   #6
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No, I mentioned it was audible, I could hear, it's loud & clear
The knock sensor hears false knock too. How interesting...
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Old 01-09-2014, 04:43 PM   #7
leforce
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The knock sensor hears false knock too. How interesting...


Knock sensor hears engine noises, misc noises, assumes it knock when it's not, that's false knock.
However, when a 'human' hears knock, it's real knock!

Have you ever heard engine knock before??
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Old 01-09-2014, 07:13 PM   #8
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Knock sensor hears engine noises, misc noises, assumes it knock when it's not, that's false knock.
However, when a 'human' hears knock, it's real knock!

Have you ever heard engine knock before??
Sure.

Last edited by ProfessWRX; 01-09-2014 at 07:23 PM.
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Old 01-09-2014, 10:58 PM   #9
nmlittlebigman
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Too little timing can cause knock too as does high EGT's.

Interesting thread here: http://www.romraider.com/forum/viewt...t=4670&start=0
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Old 01-11-2014, 01:36 PM   #10
cowboy_Rob
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What gas are you running? I was under the impression the Jdm 2 liters were high enough compression they couldn't run stock map stock boost on US spec fuel
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Old 01-12-2014, 07:21 AM   #11
quazimoto
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What gas are you running? I was under the impression the Jdm 2 liters were high enough compression they couldn't run stock map stock boost on US spec fuel
Yup. This could be an issue.
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Old 01-12-2014, 05:54 PM   #12
leforce
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Yup. This could be an issue.
I'm aware of this issue, I've been working on JDM roms for quite some time now, they are a bit aggressive but I rarely had an issue with knock when using 93 fuel. In some instances I had some mild knock that was easily eliminated by decreasing 1-2 degrees of timing.
But this time, it's a different story considering the amount of timing I had to remove to eliminate knock while using 93 fuel. Thus, I'm suspecting an electrical issue, I once had a similar problem with an Evo & the cause was a faulty ECU & got fixed by replacing the ECU.
So, my next step will be to swap the ECU, flash the same rom & see how it goes.
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Old 01-14-2014, 09:13 PM   #13
Paidfor
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You say its a 2002? Whats the mileage?

I may have missed it but i assume you've had it apart once or twice before. But lets say its never been into. My 04 with 46000 miles was FULL of carbon and soot when I tore into her for the first rebuild.Very suprising cuz I always ran 93 oct. I do know that years of carbon and coke on the valves will severely affect the amount timing the engine can take tho. Those old F150s with the 4.6 are horrible with valve clatter caused by carbon build up. One WOT pass and it sounds like the valves are gonna fly out. Easily fixed with a couple of fuel induction services (basically sucking some seafoam equivalent **** down the intake thru various ports on the manifold). Smokes like hell during the procedure too.


Idk ...maybe a issue for you...may not.
I feel like that guy on reading rainbow haha "The more you know"
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