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.

 

No knock retard is ok.

 

audible knock? or just displayed knock?

 

I get this same thing with my BB logged tune. Mine is just displayed knock, but I have seen as much at 8-9* knock retard. Always when pulling a hill without downshifting, when the engine has to lug its way up the hill.

 

Was it real knock or burst knock?

 

Sounds like your tune is way off. You should have 0 knock all the time.

 

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.

 

what octane are you running?

 

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 a 87 octane tune and was running 87.

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.