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Knock Retard when accelerating

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xxmattfxx

New member
I've been trying to trace down the cause for a while now, and it wouldn't be that big of a deal if I weren't getting at least 1.9* of KR whenever accelerating. At Idle, if I give it gas I will get a vibration in the 1100-1200 RPM range and the scanner will occasionally show some misfires mostly in cylinder 4. I've changed the plugs, wires, fuel injectors, and sprayed for vacuum leaks without any success. I am running a stock pulley, and have no engine codes.
 


Coil Packs...I bet there or the ICM...

Hope you find it...as for the KR. Could be false too. Check your motor mounts...I've seen some that have collapsed and caused things to make contact (I.E. DP & Sway Bar) and cause false knock.
 
Need to post up a scan or something more. I wouldn't be too worried about 2*Kr on stock engine/pulley though...
 
1.9* of KR is during normal driving/acceleration, it can get up to 5.6* at WOT. I scanned with EFI Live which uses it's own propriatary format. But here is s snippet, one at idle...one at a brief WOT run.

IDLE
RPM:734
o2 #1: .807v
o2 #2: .009v
SPARK Deg: 27
KR: 0
INJDC1: 4.777
INJDC2: 4.777
AFR: .5
MAF: .98 lbs/min
ECT: 196
IAT: 154
LONGFT1: -2.3
LONGFT2: -98.4

WOT
RPM: 4585
o2 #1: .924
o2 #2: .017
SPARK Deg: 7.0
KR Deg: 5.6
INJDC1: 59.705
INJDC2: 59.705
AFR: 1.00
MAF: 21.91 Lbs/Min
ECT: 196
IAT: 147
LONGFT1: -0.8
LONGFT2: -96.9
 




Haven't made a whole lot of progress on this issue but I have done quite a few more tests.

-Injectors Replaced (was an occasional few misfires at idle)
-Upper Radiator supports replaced (rubber had cracks in them, suspected false knock)
-Spark Plugs and Wires Replaced (again, misfires at idle)
-LTFTs close to zero
-230 degrees at the inlet and outlet of the catalytic converter. (no other indication of a bad cat...smell, glowing, lack of exhaust)
-Fuel Pressure within spec. (idle spec)
-No Trouble codes
-Front O2 sensor replaced

I'm not quite sure where this KR is coming from, I have stock pulley and all other performance related mods are more, restriction reducers...Cold air intake, U-Bend Delete, Magnaflow mufflers.

What I am seeing now seems to vary with the weather and the temp of the engine. Taking a simple drive to work, or a friend's house I'll look down at the max KR and see something near 5 degrees. On the highway in higher speeds, I'll see KR fluttering around a consistent 1-2 degrees even with cruise control on.

There are other things that are possible culprits that I could throw money at, but I'd rather have some guidance based on my conditions and save a couple bucks.
 
sorry to thread jack here but how did you get the EFI live scanner to work? my buddy has one and we tried to use it. no pcm selection would let us scan my gtp.. which one did you select to get it to work?
 
I chose "Gen III LS1 99-08 PCM", but if I recall I've used others without much trouble, haven't done anything special...it just works.
 


Check out the coils, they could send out a weak spark. Do you ever get a misfire while accelerating? What are your plugs gaped at?
 
^^that is what I was gonna say...or it is false knock. Check the motor mounts and sway bar in the front...might be broken or the mounts might be shot.
 
Im trying to read the scan but I think EFI is giving some inaccurate readings for everything, the kr, rpm's, ect, iat and ltfts look about right, but everything else is innacurate. It is very well possible that you just need a tune and richen the car up a bit and remove some torque management.
 
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