5.7l LS6 Timing jumping under WOT conditions

[CancerJCC]

I'm not sure why my timing is jumping all over the place when I go WOT. A little background...

I just recently (This problem has been around since) went to true SD from a MAF/SD hybrid tune. The problem was never present when I was hybrid and the only things I've changed are the MAF fail high to 10hz and zeroed out the MAF table and physically removed the MAF.

This has to be something simple because as you can see from the screenshot it falls from a steady 18* to all over the place. I am not getting any KR anywhere? Thoughts?

Screenshot is taken from log:

[LSxpwrdZ]

Try to disable M6 spark smoothing and then log all the spark modifier's on a pull and that should help pinpoint where your timing is being pulled.

[CancerJCC]

Try to disable M6 spark smoothing and then log all the spark modifier's on a pull and that should help pinpoint where your timing is being pulled.

Thank you for the reply. I will try that out tomorrow and update with the results.

[Russ K]

Disable the negative spark burst knock cells.

Russ Kemp

[gn2beatu]

The bumps at the shift points is TM.

After you disable the burst knock, go back and log for KR. You will most likely have to pull some timing in the low-mid RPM / high vacuum areas. I know I did.

[CancerJCC]

Attached is the log from today. Doesn't seem anything is at work lowering my timing.

Disable the negative spark burst knock cells.

Russ Kemp

Thank you. I have done so and will flash and run this tomorrow.

The bumps at the shift points is TM.

After you disable the burst knock, go back and log for KR. You will most likely have to pull some timing in the low-mid RPM / high vacuum areas. I know I did.

All of my TM is disabled so I'm not sure how that can be. Are you speaking from looking at my tune or in general? I'll see what Russ Kemp's fix does and report back.

[CancerJCC]

Disable the negative spark burst knock cells.

Russ Kemp

Thank you very much sir. That seems to have taken care of it! (Log attached if anyone cares to look).

That said while I have the sperts in here....Is any KR acceptable on WOT shifts? It can be seen in the log attached but doesn't occur when staying in 4th only, for instance.

[Russ K]

I would install a 160* stat & lower the fan temps to suit. Also with a boosted engine, install 2 heat range colder spark plugs, Champion RS9YC gapped at .035-.040 works well.

Then remove 2* wot spark timing.

Russ Kemp

[CancerJCC]

I would install a 160* stat & lower the fan temps to suit. Also with a boosted engine, install 2 heat range colder spark plugs, Champion RS9YC gapped at .035-.040 works well.

Then remove 2* wot spark timing.

Russ Kemp

I've read the LS motors run best at 190ish. In other words lowering the operating temp on a DD car is not the best idea that everyone thinks it is.

Fan temps already lowered.

Plugs are already two ranges colder. (NGK TR 55 or 6 whichever is colder, can't remember)

Spark is what Magnuson runs on their 112 blowers. I could remove some if you think I need to but I'm not knocking at WOT. I guess I'll look into it a bit more and adjust as necessary.

Thanks again for the advice. Any thoughts on acceptable KR on hard shifts? False or real?

[LSxpwrdZ]

I would put a set of 7's or 8's in there fresh and make a couple pulls WOT and pull over and pull a few plugs. Then add or subtract based on the heat you put into the plug. Before I had a dyno this was the way I tuned timing on power adder setups.

Also to help keep timing in it pull some timing at peak torque which is where peak cylinder pressure is also. Getting a nice curve to the timing will broaden your powerband and maximize overall power.

[CancerJCC]

I would put a set of 7's or 8's in there fresh and make a couple pulls WOT and pull over and pull a few plugs. Then add or subtract based on the heat you put into the plug. Before I had a dyno this was the way I tuned timing on power adder setups.

Also to help keep timing in it pull some timing at peak torque which is where peak cylinder pressure is also. Getting a nice curve to the timing will broaden your powerband and maximize overall power.

Thank you for the helpful information. The timing curve I'm running belongs to the Magnuson 112 supercharger base tune. While its not optimal it is similar to what I need and has been a good starting point while I dialed in the other things.

Timing is next though so thanks again!

[hiperf454]

Cancer,
I run the 160 stat and the fans run at 160 it gets really hot here. this is what I have loaded in there now.Let me know what you think of my magnison hacked on tune also. I just bought a back belt for mine it was slipping.I ordered a KaTeck belt tentioner and that should fix it. I got the gatorback on there. I will put the new belt on the rear tomorrow to fix the slip. Im going to take your advise on the plugs and change them tomorrow. I use my trips to work to dyno mine. I downloaded your suggestions and will try them on my car tomorrow. Thanks for the help guys!