How much knock retard is ok?

[joutlaw]

This is on 2004 Silverado Z71 with the 5.3L V8. It has a custom 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.

 

[OILFIELDTRASH]

I hope this isn't your main mode of transportation. Playing with a motor is all fine and dandy for something that wont be missed if it decides to crap out on you like a weekend car.

 

[joutlaw]

I hope this isn't your main mode of transportation. Playing with a motor is all fine and dandy for something that wont be missed if it decides to crap out on you like a weekend car.

It's the main mode, but I'm not modifying anything. This is just logging what ECU sees and creates .csv of the logs entries.

 

[OILFIELDTRASH]

Have you tried running a stock tune to see the difference? With the mods you have I don't see why you'd need a different tune. I hope you're the guy that installed the servo and whatnot. Otherwise that's a red flag that the previous owner dogged that truck. As soon as I see spoiler add ons, wheels, motor add ons etc.. I immediately rule out that car for purchase.

 

[joutlaw]

Have you tried running a stock tune to see the difference? With the mods you have I don't see why you'd need a different tune. I hope you're the guy that installed the servo and whatnot. Otherwise that's a red flag that the previous owner dogged that truck. As soon as I see spoiler add ons, wheels, motor add ons etc.. I immediately rule out that car for purchase.

Custom tunes are not like handhelds in order to go back to stock. My tune was done by logging with an EFI Live OBDII device, then sending that file to the tuner. He then sent me an ECU with an updated tune and I mailed back my stock ECU to him. I can get my stock tune back, but it would require vehicle down time while ECUs are swapped.

The reason I went with a tune was that GM cripples these motors and transmissions from the factory with "Torque Management". My tuner removed 80% of TM from the ECU and transmission. With tow haul mode on, it removes 100% from the transmission tuning. It really woke the truck up and made the 1-2 and 2-3 shifts much faster. I installed the corvette servo and it went a step further on the 1-2 shift, enough where I can break the tires free on the 1-2 shift if I push it really hard.

Not really concerned about selling this truck. Visibly, other than the magnaflow it appears stock. The servo is internal transmission component. I have dogged every vehicle I have owned.