How much knock retard is acceptable?
06-09-2006, 10:44 PM
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How much knock retard is acceptable? I was looking over a run from the track a few weeks back logged in AutoTap and I am getting between 2 to 3 degrees of KR from the top of 2nd gear through the top of 3rd. I'm not getting any misfire counts though.
How much Knock retard is acceptable or should there be none at all ?
How much Knock retard is acceptable or should there be none at all ?
06-10-2006, 12:38 PM
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If you're pinging then you are advanced past the point
of peak torque and the engine is beginning to fight
itself. You need to figure out whether you're long on
spark or short on fuel, and whether this is an all-
cylinders or a one-cylinder problem.
Misfire detection is set up pretty tricky and thresholds
can be set so high as to be useless (on purpose, or
just from factory) in some regions; for example my
car's stock tune does not detect cylinder-mode misfires
at all above 3200RPM, all thresholds are 32767. So you
might well have real, undetected misfires on a WOT
pull and never be told.
of peak torque and the engine is beginning to fight
itself. You need to figure out whether you're long on
spark or short on fuel, and whether this is an all-
cylinders or a one-cylinder problem.
Misfire detection is set up pretty tricky and thresholds
can be set so high as to be useless (on purpose, or
just from factory) in some regions; for example my
car's stock tune does not detect cylinder-mode misfires
at all above 3200RPM, all thresholds are 32767. So you
might well have real, undetected misfires on a WOT
pull and never be told.
06-10-2006, 10:30 PM
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Bear with me as I'm fairly new to this and should have given a little more info.
I had the car on the dyno last fall. My AFR was rich, 12.1 to 12.3. Since then I got a new tune which was leaned out .5 afr across the board. The tuner said this should put me around 12.8 to 13.1. I've been to the track twice with the new tune. My mph used to be around 107.5 pretty consistently. With the new tune that is up over 108 consistently while my et has stayed the same.
The KR begins in 2nd gear @5100 rpm with 25.5 degrees of total timing, the o2's are at 920 bank1 and 935 bank 2 and there is 3.6 deg of knock, this is the most knock and the higest timing. I'm getting between 2-3 deg of KR from there on out. Fuel trims at WOT are 0 so the only thing to go off of would be o2 readings correct ? Those are in the 920-930 range throughout the run.
Reading in the tuning FAQ they should be around 930 on cars with LT headers, so my 02's seem to be right about where they are supposed to be ?
I'm not pinging and not getting any knock during normal driving or in 1st gear at WOT. I'm thinking of trying 100 octane next trip to the track and seeing if that will help. Otherwise I can always pull timing out or add fuel. I'd probably try adding fuel first. How much total timing should I be getting ?
I guess it's possible my y-pipe is hitting but I sure haven't heard or felt it hit. I would think if it was it would be in first gear or the beginning of 2nd though right? and I'm not getting any KR there. I hope some of this made sense.
I had the car on the dyno last fall. My AFR was rich, 12.1 to 12.3. Since then I got a new tune which was leaned out .5 afr across the board. The tuner said this should put me around 12.8 to 13.1. I've been to the track twice with the new tune. My mph used to be around 107.5 pretty consistently. With the new tune that is up over 108 consistently while my et has stayed the same.
The KR begins in 2nd gear @5100 rpm with 25.5 degrees of total timing, the o2's are at 920 bank1 and 935 bank 2 and there is 3.6 deg of knock, this is the most knock and the higest timing. I'm getting between 2-3 deg of KR from there on out. Fuel trims at WOT are 0 so the only thing to go off of would be o2 readings correct ? Those are in the 920-930 range throughout the run.
Reading in the tuning FAQ they should be around 930 on cars with LT headers, so my 02's seem to be right about where they are supposed to be ?
I'm not pinging and not getting any knock during normal driving or in 1st gear at WOT. I'm thinking of trying 100 octane next trip to the track and seeing if that will help. Otherwise I can always pull timing out or add fuel. I'd probably try adding fuel first. How much total timing should I be getting ?
I guess it's possible my y-pipe is hitting but I sure haven't heard or felt it hit. I would think if it was it would be in first gear or the beginning of 2nd though right? and I'm not getting any KR there. I hope some of this made sense.
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06-10-2006, 10:45 PM
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A try with the 100 octane (unleaded!) would pretty
much tell you if it's ping or false knock. It would be
handy to borrow someone's wideband meter and see
the real mixture (not "should be", hard to trust anyone
who says 12.1+0.5 "should be" 12.8).
The KR is too eager and too persistent as-factory-set
to really see what the ping does after the initial KR hit.
If you settle it down some you might have a better
view of what precedes it and whether this is a steady
state mixture problem, or a very specific event that
just dogs you the rest of the way down the track.
much tell you if it's ping or false knock. It would be
handy to borrow someone's wideband meter and see
the real mixture (not "should be", hard to trust anyone
who says 12.1+0.5 "should be" 12.8).
The KR is too eager and too persistent as-factory-set
to really see what the ping does after the initial KR hit.
If you settle it down some you might have a better
view of what precedes it and whether this is a steady
state mixture problem, or a very specific event that
just dogs you the rest of the way down the track.
06-10-2006, 11:01 PM
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thanks for the help and good advice. Yeah I didn't quite see how the math worked out either-lol but if anything the car would still be on the rich side.
I'm having a cam installed sometime in the next month and the car will be dynotuned by Speed Inc. so that pretty much throws everything that's happening now out the window at that point.
Still I would like to figure it out. I should be heading to the track Tuesday night, I'll let you know what I find out.
thanks again for the help!
I'm having a cam installed sometime in the next month and the car will be dynotuned by Speed Inc. so that pretty much throws everything that's happening now out the window at that point.
Still I would like to figure it out. I should be heading to the track Tuesday night, I'll let you know what I find out.
thanks again for the help!
06-11-2006, 12:09 AM
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Is there any way you can back the timing off? I'm running pretty close to a stock table to try and avoid knock (+ 1/2 degree). I always seem to get KR at 4800rpm if I increase the table. 
