Hi guys, I wouldn't have started a new thread but it's kind of urgent... Question is, I want the car to stop the fuel cut when I decelerate so that I can properly tune it without the fluctuations when I've let off on the throttle. I can understand the RPM enable for the cutoff - I set that to 6350rpm so it wouldn't ever engage. Then the VSS I set to 110mph so that wouldn't engage until I hit that point as well. The only thing I don't know how to turn off is the map enable. Please let me know if I'm doing the first two correctly (and if not what's the proper way to do it), and if I am doing it correctly, how do you turn off the MAP enable?
Thanks!
" To study and not think is a waste. To think and not study is dangerous. "
What exactly is DFCO? Decel fuel cut option?
FU Tuning
I read this in your FAQ post (not posted by you, but posted by two others...)
Rodimus Prime
Saturday, September 23, 2006 12:01 PM
There is another step that should be added to this process to get accurate data and that is disabling deceleration fuel cut off or DCFO , reason being is that while driving the moment you let off the gas the chart will show you as being lean cause your AFR drops to 19.9 AFR in DCFO mode and the hp tuners sees that as being different from the commanded 14.6 so it shows as a lean spot on the histogram
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steve williams
Friday, May 11, 2007 11:33 AM
2 things need to be edited in the sticky....
UP top, DFCO MUST BE DISABLED or it will skew your AFR % error artificially negative during decel logging
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I was finding that the AFR would spike dramatically at points and it's hard to tell sometimes if it's just the cut off, or if it's something more serious - so I assumed by these two posts that this could fix it (not to mention it was suggested in my other post I just made).
" To study and not think is a waste. To think and not study is dangerous. "
Well I had figured that might be the way that HP does it, however it still goes way lean when I'm off the pedal after RPM and VSS are set that way... so I figured it would be more likely an 'or' statement. While I've got your attention Shifted, do you suggest having this off or just tuning the car with it on?
" To study and not think is a waste. To think and not study is dangerous. "
You can filter the results of the histogram to have a TPS > 25%, or you can do the DFCO. Its easier to do the DFCO than filter the histogram, just know that your car will run like complete ass during decel and at stops.
BTW, its not how HPT does it, its how GM does it.
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I always turn off DCFO while tuning in open loop
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
