Deceleration Fuel Cut Off
 

Does the electronic fuel injection on my 1.2 i-DSI Honda Jazz/Fit GD-5 have a "shut off on overrun" and if so, above what rpm does it work?

I'm sure it does, and it normally starts spraying fuel around 900-1500 rpm. If you have it in gear and coast down, you can feel the jerk as it kicks back in.

Thanks. I take it I am more likely to feel the jerk in a lower gear?

Yes, but it'll also be at a lower speed in a lower gear. You should still be able to feel it in a higher gear.

Use a shallow sloping hill and top gear, you'll feel exactly when the fuel comes back in.

I like checking in first gear. Much easier to feel the fuel kick back in. Also safer to be staring at the tach at lower speeds.

Tried it in third, this morning, and though revs dropped down from 2500 to stalling I felt absolutely nothing!

Was the engine warmed up? If you're still in high idle mode, it won't kick in.

It had warmed up and tick-over was about 700 rpm, but I'll try it again after a good few miles when engine is really hot.

I have a 2000 accord automatic transmission. I use the Torque app with a blue tooth OBD2. Torque has a fuel consumption display. It shows the same amount if I'm coasting in gear or in neutral so it looks like I don't have DFCO. Any other way to see if my car has DFCO

I've used the torque app and the scangauge on both my cars and found the torque gauges don't show DCFO but the scangauge does. I know both my cars have it so must be a problem with the torque programming.

I find I usually can't feel it kick back in unless I'm on a bit of a downhill.

I feel it sometimes, and sometimes I don't feel it. That goes both for cut-off and cut-on.

Thanks. Does Scangauge actually have a field called Dfco, or are you looking at reading and inferring from that?

I have a 2000 Accord V6 and definitely have DFCO as noted on the ScanGage II mpg. Rpm up to 2000 and let of the gas. With the automatic I can down shift all the way to first gear and keep DFCO as long as the rpm's don't drop below 1200.

0 Load = DFCO, you don't need a specific parameter for it.

Right enough. On the ScanGauge Load or LOD is the percentage of power being generated and if the cut off is engaged that will be zero. At tick-over there will be some small amount of power or LOD displayed.

When you guys say load. You mean Engine Load or something else?

Yes engine load. Instant lhk will go to 0 as well or 99999 mpg.

I read that for automatics to enter dfco you have to be in d3. Does anyonr know if that's true? I haven't tested it yet. I'm worried if I shift into d3 whie driving I'll ruin the transmission

Nah. That does not sound correct to me. I would think it is all about throttle position and RPM. With throttle closed and RPMs above maybe 1500, or perhaps 2000, I would think your car would slip right into DFCO. You might switch gears like that to raise the RPM above a necessary threshold but it is not likely a requirement that you be in D3 specifically.

Shifting to d3 won't do any harm unless you were going extremely fast. You are just doing manually what the trans normally does automatically. I agree that doesn't sound right for DFCO though. Not all engines have the same parameters for DFCO (my Rondo will only cut fuel below 2000 rpm) but it won't require any abnormal input from you to cut in. If you meet the conditions, it will work.

My previous car was a Volvo S40 automatic, and at anything other than high speed, lifting off the throttle caused the revs to drop to about 1200 - 1500 rpm. There was so little engine braking. From what I understand, for DFCO you need the engine braking to keep the revs above the threshold (as you say, about 2000 rpm). The only way I got appreciable lower speed engine braking was to drop down to D3.
I believe the torque converter didn't lock up until 50 mph in Drive.

It won't nessacerally kick in at the same rpm in different gears

After using my scan gauge for a few tanks now mine will will kick in at much lower rpm in high gears at speed then it will at lower speeds and rpms.... Which isn't something I saw coming

I often find it more efficient to roll in neutral down shallow hills

My ScanGauge is ordered, and on its way. What I am doing meantime is coasting in neutral then going back to a high gear when I need to control my speed. My Jazz/Fit is rather light and doesn't build up a great deal of stored energy. On a shallow downgrade, in top gear, it will slow to an unreasonable speed very quickly. In neutral it goes on for ages.

Look in torque for the upstream oxygen sensor output. If you're at 0, then you aren't burning any fuel and you're in DFCO.