How much knock retard is ok?
05-01-2012, 09:30 AM
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How much knock retard is ok?
This is on 2004 Silverado Z71 with the 5.3L V8. It has a Blackbear data logged tune with K&N filter, magnaflow catback, and a corvette servo.
I recently got ELM327 OBDII scanner and have been using Torque with GM's extended PIDs.
I logged my drive home from work yesterday. I saw as much 7.8 degrees of knock retard. This was 2700RPMs in 3rd gear, 64MPH, throttle @ 67%, engine load @ 42%, and timing advance 22.5 degrees.
At WOT I saw 5.27 degrees of knock retard with 21.5 degrees of timing advance.
Most of the time I did not see knock retard though. It was mainly in high load situations such interstate on ramps or inclines.
My concern is that my tune may be the culprit. I would imagine most stock GM tunes exhibit knock retard too though.
Attached are the log files.
I recently got ELM327 OBDII scanner and have been using Torque with GM's extended PIDs.
I logged my drive home from work yesterday. I saw as much 7.8 degrees of knock retard. This was 2700RPMs in 3rd gear, 64MPH, throttle @ 67%, engine load @ 42%, and timing advance 22.5 degrees.
At WOT I saw 5.27 degrees of knock retard with 21.5 degrees of timing advance.
Most of the time I did not see knock retard though. It was mainly in high load situations such interstate on ramps or inclines.
My concern is that my tune may be the culprit. I would imagine most stock GM tunes exhibit knock retard too though.
Attached are the log files.
05-01-2012, 11:48 AM
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Looking at those logs I also notice that I see it during some of the 2-3 shifts. Does torque management show up as knock retard or is timing advance reduced? Or are they essentially the same thing?
I have 80% TM reduction and 100% on the transmission tuning with tow haul mode.
I have 80% TM reduction and 100% on the transmission tuning with tow haul mode.
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05-01-2012, 12:21 PM
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Looking at those logs I also notice that I see it during some of the 2-3 shifts. Does torque management show up as knock retard or is timing advance reduced? Or are they essentially the same thing?
I have 80% TM reduction and 100% on the transmission tuning with tow haul mode.
I have 80% TM reduction and 100% on the transmission tuning with tow haul mode.
07-09-2012, 04:04 PM
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Torque management just reduces the timing to a low value for the length of time it takes to shift gears (so probably a half second). Knock retard is sound data coming from the knock sensors and what they aren hearing when predetonation occurs. Now, I have seen low low amounts of false knock mainly due to header noise, at random times but its usually a value around .1-1.0* of knock
I have had this tune for around 3 years and never noticed any issues. I haven't been as hard on my truck and may be why I am noticing it now. I can audibly hear pinging which I thought was my exhaust rattling.
For giggles, the other week I put in 89 octane. I don't hear the pinging and the truck is running better it seems. I also don't notice what I thought was transmission shuddering at 55-60mph in OD. I think that that this was load knock occuring.
Even more strange is it seems my TC is locking at a greater rate. i.e. my RPMs at 75mph are 500-1000 RPM lower than they were before. I have 3.73s with a 265 tire.