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hello gents,
I am pretty new to tuning, and I'm doing some tuning for a friend, and i think i have his tune pretty close, but we are seeing a few degrees of Knock Retard. It sometimes happens randomly, and other times it happens under a load.
Let me start by saying im no expert tuner, but here is what I see.
In the data log at 4:54.44 - With 100% TPS, the RPM drops down, right after this you begin to see knock. I can only assume this is the transmission shifting since you are not logging trans current gear. It could be possible that something on the motor\trans is hitting the frame and causing false knock during a hard shift.
Can you give me more details of the setup? Swap car or stock application? Headers?
I would look for causes of false knock as i dont see anything abnormal in the tune. Have you tried lowering the timing in the effected area and see if knock goes away? Have you tried running higher octane gas to see if that helps?
hope this helps..
Last edited by Compsystems; Mar 9, 2017 at 01:26 AM.
Can you give me more details of the setup? Swap car or stock application? Headers?
I would look for causes of false knock as i dont see anything abnormal in the tune. Have you tried lowering the timing in the effected area and see if knock goes away? Have you tried running higher octane gas to see if that helps?
hope this helps..
The vehicle was stock, 2004 chevy 2500hd with a 6.0 lq4, still has the original exhuast manifolds. We just swapped the cam and springs in. I didn't try and remove any timing yet, I'm still using the stock timing table, which is very conservative. And I thought that timing table SHOULD work without having to remove any timing. For example, timing advance is only 11 degrees with the engine under a load at 5000 rpm. We haven't used higher octane gas yet, that should probably be our next step
Don't shoot for any particular number. Give it the fuel it needs for the timing you want to run and the octane you are wanting to use. Timing/fuel/octane all work together. Changing any one can effect the others. Often being in a higher gear where the load is higher requires different A/F than a lower gear. Unfortunately we don't have the ability to fuel differently in different gears.
not on my home laptop to look at the tune but IIRC aren't the truck tune for KR more sensitive and aggressive than LS1s in general? also I noticed the data at frame 1090 in the first pic that IDC is at 88% at only 4280RPMs? do you have a wideband to see what the AFR is at WOT?
edit nevermind I see AFR showing 12.56 but is that the PCM AFR or an actual wideband that's hooked up to HP Tuners?
not on my home laptop to look at the tune but IIRC aren't the truck tune for KR more sensitive and aggressive than LS1s in general? also I noticed the data at frame 1090 in the first pic that IDC is at 88% at only 4280RPMs? do you have a wideband to see what the AFR is at WOT?
edit nevermind I see AFR showing 12.56 but is that the PCM AFR or an actual wideband that's hooked up to HP Tuners?
The truck settings may be more sensitive, but I haven't look at them in the tune to see, to be honest, I'm not really sure what to look for.
And yes, the afr reading was taken with my wideband that is hooked up to hp tuners
my general rule of thumb is if the IDC is over 80% at full throttle at top of the RPM shift, the injectors are maxed out. seeing that its only at 4280RPMs and its already running 88% open with a 12.6AFR tells me that is the case. not to mention running only 10-12* of timing.
is the 4280 at the top of the gear or bottom of the gear? hard to tell in the picture.
my general rule of thumb is if the IDC is over 80% at full throttle at top of the RPM shift, the injectors are maxed out. seeing that its only at 4280RPMs and its already running 88% open with a 12.6AFR tells me that is the case. not to mention running only 10-12* of timing.<br /><br />is the 4280 at the top of the gear or bottom of the gear? hard to tell in the picture.
<br /><br />The 4280 is actually after the top of 2nd gear and before the bottom of 3rd gear, it's right in between. But ya, the injectors were at 108% duty cycle at the top of second gear. So at this point, the the first priority is getting larger injectors in this engine to feed it.
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help diagnosing lq4 knock retard 
