ZL1 knock retard stock tune
 

I just downloaded Hp tuners and got the mpvi2. My car has a elite carbon air intake and a Katech ported 87mm throttle body running the stock tune. I was getting knock retard in third gear pulls of about 4-5deg just at about 6000rpm and it declines the retard till 6350 and once at around 3500rpm for .7deg.
If I did a pull in second gear the car had zero knock retard for 3 straight pulls. Is there something I look into on this or be worried about. I haven’t done any changes to the tune yet but am thinking that it’d be best. I assume my intake and throttle body has leaned it out too much For the longer gears?

Make sure to log any type of timing modifier in the channels pids. Off of the top of my head:

Intake air temp timing
Coolant timing
Torque management timing
Flex fuel timing
final timing
knock retard timing

I think that is it, something like 5-6 timing tables that need to be logged so you can actually see what is pulling the timing.

The stock IAT tables start pulling timing at 85° of intake air temps. Also the cars are tuned from GM on 93 octane, so if you are running 91 the chances of logged detonation increase. The warmer it is outside the higher the chances of detonation increase. The higher the load is on the engine and if the engine is lugged down, it can cause burst knock.

If this was a WOT pull and you noticed the knock being recorded I am going to go with it is fuel knock, not enough octane in order to keep knock at bay. If you have access to E85 you can add 2 gallons of E85 to either 100% 91 or 93 and it will help with knock. That puts you at 91 E10 or 93 E10, to be honest you can go as much as 3 gallons which is E15 and it will really help with detonation and in increasing the octane of the fuel.

Hi Kyle,


Our E2 and E2-X catchcan systems for the LT4 engine removes up to 95% of the ingestion causing detonation and the associated KR. In fact, your in Orlando. If you can drive to the Tampa area their is an R&D shop that will install it no charge and if you track your gas mileage there and back, you should see 8-10% increase in it as well as your engine does not run as efficiently when ignition timing is pulled and the reduction in KR results in not only a slight power gain, but increase fuel economy as well. And keeps you engine oil clean up to 3 times as long as it will now.


If it does not, we will buy it back and do the uninstall free of charge as well.


Let us know.


Thanks!

I’m in the Orlando area as well and willing to make the drive!

I relogged a couple more runs and kept getting the 3rd gear knock at WOT around 6000 rpm. I am in the Orlando Area and run only 93 octane but Added a fuel octane booster anyways to test it out. On my very first run after a little bit of octane booster from Lucas there was 0 knock retard and have continued to get no knock since the booster. Thanks for the advice with the octane of the fuel. Im going to assume the gas in my area isnt actually 93 for now.

I have just started logging my car today. Just curious what was the max intake manifold pressure psi you saw and your max throttle position. My car would not get over 83% the max psi I saw was 13.5.

Just to confirm yours and TJays findings on octane I also had 0 KR, running 91 with 3 gallons of e80.

The OEM timing map for the GM 6.2L engines is pretty aggressive from the factory. While they can run on 91, they really need 93 and depending on how hot it is outside may even need more octane to keep KR at 0 or the addition of 2-3 gallons of E85.

83% is the correct WOT reading in HPT's.

Once you add say 3 gallons of E85 to the tank you need to make sure in the future you only add 15% of the amount of fuel it takes to get back to full otherwise if you continue to add 3 gallons you will eventually increase the E85 mix well above the E15 range.

So as an example, if the 1st time you add 3 gallons of E85, you are now at E15. If you take the tank to half on the gauge it will roughly take 9-10 gallons to fill up again, you dont want to add more than 1.5 gallons of E85 to keep the mix at E15.

In order to keep the mix right you will need to know roughly how many gallons of gas it will take to get back to full again.