For all those interested:

Draw your own conclusions.

K_C_

 

do the 2007s have the same feature

 

My guess would be yes - others might confirm.

What's important to note for economy is that fuel cutoff occurs on deceleration w/ throttle valve closed.
Deceleration is in gear slowing of the car.

Coasting to a stop in neutral does not engage the fuel cutoff.

K_C_

 

great info. I have a 2002 Japanese spec and it does this. I had no idea what was going on and became concerned, but this has confirmed its supposed to do that. put's my mind to rest.

 

I think you actually have to be braking for it to occur. I tested it coasting in and out of gear... and UltraGauge was reporting less fuel usage out of gear (engine drops to idle). It's a bit harder to test when braking though, since I'm not very consistent.

But, I'm not even sure UG is properly picking up fuel consumption... I don't know how it gets the info. From the ECU, sure, but how does it figure that out? If fuel really is cut off in gear while coasting, then the ECU isn't picking up actual fuel usage, but "estimating" it based on something else (like RPM x fuel that normally would be injected).

 

Throttle cutoff w/ the UltraGauge is a setting that senses the throttle position and applies zero fuel usage to the MPG calculation over the given time/distance.

It's on or off, same application for all set-ups.
Reading the manual and asking UG tech cleared that up for me.

It is some what accurate on the MPG's. To my calc it runs consistently conservative, however.

How are you watching fuel usage?

The brake position switch isn't part of the fuel-cut off [least I don't see it]. It does effect the idle control system on a cold start.

 

It is a feature that the BMW motorcycles had in 1994 and possibly 10 years earlier... You could hear and feel when it would come back on in 1st gear when it was at about 8 or 10 MPH..... Those bikes are very quiet and much quieter than my Fit.

 

one of the default menu stats is G/H (gallons per hour, I assume)... and when I lift off the gas pedal, in gear, it drops to some given level, usually about 0.40 G/H, at the speeds I was checking. But when the car is idling or if I'm coasting out of gear... the usage is about 0.20 G/H. Even when I was going downhill and lifted off the pedal and let gravity keep the speed constant, it was still twice the usage vs idle/neutral coasting.

I'm half deaf (technically, complete one-sided), so i figured I probably wouldn't be able to hear the difference anyway. I barely noticed it in the Insight II when I test drove it. I think I noticed the feel more than the sound.

of course, idle is roughly 1k rpm, so it clears the rpm requirement for fuel cutoff.

 

The difference between the BMW motorcycles and the Fit is that there is still a small amount of fuel entering the combustion chamber in the Fit but not the BMW.. The Fit retards the timing way back to prevent damage from combustion of a very lean mixture, the BMW shuts down the injectors as well as the fuel.. That is why the transition is not noticeable on the Fit and is on the BMW bikes.

 

So it's not a complete cut off? then that makes sense of the numbers I was getting.

during one of my deliveries, I checked out coasting in and out of gear. the (instant) G/H numbers of the UG showed that the usage with my foot off the pedal closely followed the RPM. 0.2 G/H at around 800 or so RPM (out of gear), 0.40 at 1.6k RPM (4th gear) and 0.60 at 2.4k RPM (3rd gear) at about 35 MPH. Actually, I'm guesstimating those numbers since we don't have a digital RPM display (though I could set the UG to show it, I suppose). And G/H numbers were just rounded for simplicity.

That being said, I guess I should retract my previous statement about idle RPM clearing the requirement for cutoff.

The only other thing I can think of... the throttle isn't fully closing when I completely lift off the gas pedal.

 

I found this but it might just help raise more questions. Fuel and Emissions System Description - Idle Control System/Fuel Supply System (K20Z)

Both my Fit and Civic did this. Zero fuel used when the pedal is released in open loop. Running the AC and lights, might add fuel due to engine load.

Here is another link http://www.hondafitjazz.com/engine_f..._emissions.htm

 

what are you using to tell you fuel usage, ScanGauge? Maybe I need to go into UG and look for another gauge for fuel usage.

Maybe the ECM (unit/module, same difference) is keeping the throttle open because of my headlights. I'm using HIDs, so it "should" see less load than stock halogens. In any case, the thing is... I see the same numbers when I did it earlier in my shift (when I didn't need/have my headlights on).

So, I have no idea.

 

As near as I can tell the "Fuel Usage" shown by the UG is not something to hang your hat on.

UG MPG Accuracy

I would certainly suspect the Gallons/Hour number.

The reference I quoted is from the 2009/2010 Honda Fit Factory Service Manual.
With current to the injectors cut, under the given parameters, there will be no fuel delivered to the cylinders.
Spark is still delivered, but without fuel mix present there is no combustion.
An off shoot is a slight 'cooling' of the engine in that the cylinders are sucking air.

No other parameters are given or referenced regarding Fuel Cutoff.

The only conclusion I can draw, and the reason I originally posted, is to show that coasting out of gear [essentially in idle mode] is not a way to conserve fuel, as some have falsely assumed.

--------------------------------

The Cadillac NorthStar will selectively drop alternate cylinders this way when an extreme engine temp is reached and allow limited drive-ability to reach a safe harbor without undue damage to the engine.

It's called 'Camel Mode'.

 

You will notice that the ignition timing is also severely retarded when coasting in gear... I believe that is done as a safe guard to prevent a lean burn condition if there is fuel leakage from any of the injectors...

 

Coyote - You have a scan gauge, right? Question came up in another thread, does it show tranny temp?

 

It only shows what there is that has sensors.. It has IAT, Water Temperature, voltage, ignition timing, throttle position, MPH, RPM, etc. but nothing on oil or as far as I can recall transmission... I can only monitor 4 things at a time so the first 4 listed is what I normally have it set on.

 

Thanks mate. The UG will sense oil temp, but only if a sender is present. In the Fit there's no sender/no oil temp. It has no reference to transmissions at all. I'll venture to guess these isn't a tranny fluid sender either.

 

I have both the SG and Ultra. I like the Ultra because of the multiple screens. You can look at other setting and still see the fuel usage.

Lights on or AC usage will not allow the full fuel cutoff. There is also some thing to do with the Lock up of the converter too with the automatics. The ECU adds fuel under slight loads because it does not know what you as the driver is going to ask for meaning passing power or more engine loads by lights or a change in engine conditions.

 

Once again I am enlightened by SilverBullet.

 

Thank you I try. I will be sending some info your way when I make time to find it and not working. The weather has been awesome this past week. My mpg is a little lower but that is because the air is dryer than in the summer. Requires more octane than the premium I use. The barometric pressure is higher too 29.2 compared to 28.6 all summer.

I think there is a trans temp and oil temp available in both SG and UG but that is if its applicable.