Quote:
Originally Posted by PagalDesi4Life
Tundradrenalin: How did you come about to make those adjustments to your fuel cutoff? Mechanically I don't know too much so I am curious as to how you got the calculations to modify your current settings. What benefit can you recieve from doing so?
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What are the benefits?
Greater accuracy I suppose.
How did I come about the numbers?
I monitored the fuel cutoff in terms of what the SGII was showing me, as well as what I could hear the engine doing. For instance, if you gas it to 3500RPM, then let off the gas and coast for a bit, you'll notice the engine slowly reduces the RPMs. But you'll also notice that the MPG # on the SGII reads about 5mpg --> 8mpg --> 18mpg --> 45mpg --> 95mpg --> 9999mpg. (FYI, with exception of the 9999, these are all made up numbers for sake of the explanation.) Ok, the 9999mpg reading is telling you the engine has cut fuel and is now coasting without using any fuel. This is when you should be braking with the pedal, it's what people refer to as "not aggressively braking".
Back to the cutoff... When the 9999 came up, I could also hear the engine let up. It's very audible if you know when to listen for it. I then looked at my LOOP, it went into CLOSED LOOP, which I expected, so that's not a very significant observation. Then I looked at the TPS, Throttle Position Sensor, setting and saw it was reading 15 on the SGII. Ok, if the TPS is reading 15, and my engine just cut fuel, I should set my cutoff to 15, right? But then I thought,
the engine is cutting fuel at TPS=15, why shouldn't I put the CUTOFF=16? So I did. And now I'll test it out for a couple months and adjust as needed. Maybe I should go to 15 for the CUTOFF on the SGII.
NOTE: all testing and observations were done with the A/C off. When you turn the A/C on, the engine is revving on&off just to keep the compressor running, and you don't always get a fuel cut (ie., mpg reading 9999).