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Old 08-09-2007, 03:18 AM   #1
majunche66
Scooby Newbie
 
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:
2004 sti
Blue

Exclamation knock question!!!

i am on the process of tuning my car, i got the hydra and the car ran good on the base map that was set up on the computer according to the specs(started and could drive a little), obviously i had to do a little twisting to get the car running cleaner!! when i started working my way up and i felt confident boosting the car, i noticed that everytime that i let off the gas pedal, the car game a check engine light, checked for the knock threshold and i saw the problem it was a little spike, i talked to Phil @ element tuning and i told him that i was runing just 10 lbs of boost, he told me go ahead and put some race gas to check for real knock!! during bosting the car behaves good but when i let off it i see the sipike on the KT map!!(no knock or high voltage values on boost, all under .44) WHAT COULD BE CAUSING THIS???? i had a little backfire but i managed to clean it up and got the car decelrating clean!! i would really appreciate any input!!

mods are:
GT35r turbo kit
FMIC
External W/G
Exedy twin plate
850cc inyectors
magnus intake
ported heads (stock valvetrain)


Thanks in advance!!
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Old 08-09-2007, 10:16 AM   #2
Element Tuning
Former Vendor
 
Member#: 54918
Join Date: Feb 2004
Chapter/Region: MAIC
Location: Gaithersburg, MD
Vehicle:
673 WHP Element
Tuning Pro Comp Engine

Default

It's likely clutch noise. Ease off the gas or push the clutch in and note the noise on the Knock Threshold map or a data log. If this problem goes away you just have massive clutch chatter. If you are confident this is your problem then increase the "Knock Buffer Voltage" which is what sends the Hydra into the "backup spark" map.

Situations like this are when a knock listening device is really helpful. I have heard what sounds exactly like detonation from the BOV snapping shut. Even though I heard this with the knock headset it doesn't register on the Hydra as the frequency is off enough from knock that it doesn't effect it. This doesn't mean in all cases the frequency from the BOV piston hitting the stop won't set off the knock sensor. The same applies to clutch noise.

Welcome to the world of tuning. Sometimes it's just not black and white!

Thanks,
Phil
www.elementtuning.com
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Old 11-10-2007, 07:01 PM   #3
extrememedia
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Member#: 160756
Join Date: Oct 2007
Default

I have the same problem, when I let off the gas after WOT it thinks there is knock, and retards the timing. I am pretty sure it doesn't matter, right?

MODS ARE:

GT35r custom turbo kit
FMIC
External W/G
850cc injectors
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Old 11-13-2007, 12:05 PM   #4
Element Tuning
Former Vendor
 
Member#: 54918
Join Date: Feb 2004
Chapter/Region: MAIC
Location: Gaithersburg, MD
Vehicle:
673 WHP Element
Tuning Pro Comp Engine

Default

Quote:
Originally Posted by extrememedia View Post
I have the same problem, when I let off the gas after WOT it thinks there is knock, and retards the timing. I am pretty sure it doesn't matter, right?

MODS ARE:

GT35r custom turbo kit
FMIC
External W/G
850cc injectors
My base maps typically have low timing in the high rpm deceleration areas of the timing map to prevent "lift knock." I also leave fuel in there to prevent the lift knock you get with the OEM ECM due to high timing and fuel cut so it's highly unlikely you have knock unless you've modified these values.

Just follow my instructions above and if it's not going into the backup spark map and turning on the CEL you really don't need to do anything. When the Hydra senses noise above the knock threshold value it just reduces ignition timing and adds fuel which will not hurt anything while shifting or on throttle lift.

Thanks,
Phil
www.elementtuning.com
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Old 01-05-2008, 06:47 PM   #5
Chino1
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Member#: 128985
Join Date: Oct 2006
Chapter/Region: MAIC
Location: Alexandria, VA
Vehicle:
2002 bugeye STi-ish
MBP

Default

Quote:
Originally Posted by Element Tuning View Post
It's likely clutch noise. Ease off the gas or push the clutch in and note the noise on the Knock Threshold map or a data log. If this problem goes away you just have massive clutch chatter. If you are confident this is your problem then increase the "Knock Buffer Voltage" which is what sends the Hydra into the "backup spark" map.

Welcome to the world of tuning. Sometimes it's just not black and white!

Thanks,
Phil
www.elementtuning.com

phil can you explain how exactly the "knock buffer voltage" works and how it should be adjusted if need be?

im also having a decel issue knock issue...FWIW my clutch is a noisy bioch and this prob seemed to arise after i got my clutch and LW flywheel installed.
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