Clutch fuel cutoff enabled on '13 ZL1 M6 stock tune

[hawk02]

I posted this over in the ZL1 forum last week but didn't received any responses so I thought I'd repost it here.

I was comparing ZL1 M6 stock tunes posted in the HP Tuners repository to see if GM made any changes to the file between model years. What I discovered much to my surprise is that the only change involved the clutch fuel cutoff (cfco) function. It's disabled in the '12 tune but enabled in the '13 tune. There weren't any M6 '14 or '15 tune files in the repository so I couldn't compare those model years to see if it's enabled or disabled.

Now I'm not a big fan of the farting and popping and crackling when shifting gears caused by the cfco. In fact, I find it rather annoying. As I understand its purpose is to smooth shifts and reduce some of the jerking when the clutch is let out. Sort of like torque management for the clutch. Am i right?

Seeing these differences has made me curious why GM would disable it for one model year but enable it for another. Anyone have any ideas?

[tadams72]

I don't have the answer but in for the discussion. You were the one showing it disabled is a stock tune? Changing the ECT high looks like something a tuner would do to disable.

[hawk02]

Originally Posted by tadams72

I don't have the answer but in for the discussion. You were the one showing it disabled is a stock tune? Changing the ECT high looks like something a tuner would do to disable.

I agree the high ECT value looks like something a tuner would do to disable, however, I downloaded three stock 2012 M6 tunes from the repository and all three looked exactly like the first image in my original post.

I also did a file comparison summary in HP Tuners between the 12s and my stock 13 tune and the only difference is the CFCO parameters. If you notice the enable RPM is slightly different between the two and in the CFCO table there is 5 degree difference in ramp down spark below 1536 RPM.

[tadams72]

Well that is interesting. Hopefully someone will shed some light on it for you. My best guess though is its a fuel economy and emissions factor. Perhaps also tied to catalyst health.

See if anyone else has some ideas more concrete.