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Nooby Over-run Fuel Cut question

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Old Apr 24, 2017 | 06:45 AM
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Default Nooby Over-run Fuel Cut question

The MSPNP Pro has had Over-run Fuel Cut OFF since the install and initial tuning. However, if I completely lift off the pedal below 60 mph, the MTX-L quickly reads 22.4. Above 60, it takes a few seconds to kick in, so it seems like there's a related "setting" somewhere that's working. I can't find a field in MegaLog Viewer for Over-run itself. Did I miss something?

Is that how it's supposed to work?
Old Apr 24, 2017 | 07:58 AM
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here's my question: why is overrun turned off?
Old Apr 24, 2017 | 08:54 AM
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Originally Posted by poormxdad
The MSPNP Pro has had Over-run Fuel Cut OFF since the install and initial tuning. However, if I completely lift off the pedal below 60 mph, the MTX-L quickly reads 22.4. Above 60, it takes a few seconds to kick in, so it seems like there's a related "setting" somewhere that's working. I can't find a field in MegaLog Viewer for Over-run itself. Did I miss something?

Is that how it's supposed to work?
My overrun was off when I first loaded my basemap as well. IIRC the basemap tune has very lean AFR targets under overrun condition sort of imitating overrun fuel cut but without the setting being on. But I'm also a noob and could be wrong about that, can't look at my tune right now. Post tune if you get a chance.
Old Apr 24, 2017 | 09:05 AM
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See below
Old Apr 24, 2017 | 09:27 AM
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Originally Posted by Braineack
here's my question: why is overrun turned off?
It's just the next thing I plan to deal with. But, since I had that issue with the WOT TPS% in the Alternator Control menu working when it was supposed to be disabled, I wanted to ask whether or not this is how OFC is supposed to look. It certainly is cutting fuel at low loads and TPS%.
Old Apr 26, 2017 | 09:33 AM
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Here's the current tune and a short log I did on I-95 lifting off the throttle. I need to do another log at lower speeds.

Thanks much,
Attached Files
File Type: msq
poormxdad23Apr.msq (274.9 KB, 102 views)
File Type: msl
2017-04-23_16.38.54.msl (563.0 KB, 213 views)
Old Apr 26, 2017 | 10:24 AM
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I've seen this as well when tuning with overrun shut off. Even though the VE values in the bottom row seem linearly lower than the rest, it still seems to run very lean under high vacuum. As long as it doesn't run this lean in other conditions, just turn on overrun fuel cut. Your log shows that under decel, you still have an injector pulsewidth, which means that the fuel is not completely shutting off. It'd be much better to not inject any fuel and not have combustion, than having it run very lean like that.
Old Apr 26, 2017 | 12:50 PM
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Originally Posted by acedeuce802
I've seen this as well when tuning with overrun shut off.
Thanks much. That's what I wanted to know. Do you have any recommendations for the spark or other options?




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