Does my car have fuel cut while engine braking? (1994 Honda Civic LX 1.5L MT)

[EricRyan]

I've been pondering the subject of engine brake vs. neutral coasting, and I can't find any definitive information to help me decide which side of the fence I stand on.

With the 100 miles I've put on since the last fill-up, I can already tell a huge MPG improvement using a lot of engine braking (something I've never done before as I *thought* it was wasteful) based on my fuel needle's position in relation to the F mark of the gauge. One of the most common thing I've seen come up in the engine brake vs. neutral coasting debate is whether or not your vehicle is EFI or carb'd, and whether or not your EFI has fuel cut or not.

My question is: does anyone know if my 1994 Honda Civic LX 1.5L MT has the capability to cut fuel when engine braking?

[Gasoline Fumes]

I can't imagine why it wouldn't. My '91 Civic has it. Accelerate to at least 3000 RPM in first gear with the engine warmed up, then lift your foot. You should feel the engine come back to life near idle. Mine does it at 1200 RPM. It's much easier to detect in lower gears.

[gone-ot]

...a ScanGauge-II™ would tell you by indicating a sudden drop in fuel flow quantity while braking. Do you have a SGII?

[Gasoline Fumes]

I don't think a ScanGauge will work in a '94 Civic. Monitoring the O2 sensor voltage will also show the fuel cut.

[EricRyan]

Originally Posted by Old Tele man

...a ScanGauge-II™ would tell you by indicating a sudden drop in fuel flow quantity while braking. Do you have a SGII?

1994 = OBD1 = no SG

Originally Posted by Gasoline Fumes

I don't think a ScanGauge will work in a '94 Civic. Monitoring the O2 sensor voltage will also show the fuel cut.

True. Too bad my multimeter bit the dust a while back, I guess this would be a good excuse to pick up another. What would the voltage be during fuel cut, or does is it vary per vehicle?

Thanks.

[EricRyan]

Originally Posted by Gasoline Fumes

I can't imagine why it wouldn't. My '91 Civic has it. Accelerate to at least 3000 RPM in first gear with the engine warmed up, then lift your foot. You should feel the engine come back to life near idle. Mine does it at 1200 RPM. It's much easier to detect in lower gears.

Yeah! I noticed it doing this when it falls to around 1,400 RPM where the "load" seems to lift off and it feels a little more like neutral. Awesome tip!

[Ryland]

It was pretty much standard on Honda Civic's starting back in 1978 or so, so I don't see why they would have left it off your car, so unless it was owned by a teenager who made "improvements" to it, it should be there and work.

[EricRyan]

Originally Posted by Ryland

It was pretty much standard on Honda Civic's starting back in 1978 or so, so I don't see why they would have left it off your car, so unless it was owned by a teenager who made "improvements" to it, it should be there and work.

Nice to know.

[cfg83]

EricRyan -

On my 1999 SW2, which is based on a 1996 design, I have DFCO (Deceleration Fuel Cut-Off) in 3rd gear *above* 2500 RPM. I have a digital AFR (Air Fuel Ratio) gauge so it's easy for me to see DFCO. On a 2012 car I believe the DFCO is much more aggressive, aka near the idle RPM.

However, I have heard that you can *detect* DFCO without gauges because the engine sound changes and/or you feel a "bump" when the DFCO stops. If I were you I would find some steep hills and pop it in third such that the RPM was at least 3000 in third. If the engine braking doesn't lower the RPM below 2000 RPM then I would *gently* depress the brake to see if I can detect the change in engine sound.

CarloSW2

[some_other_dave]

Look into the MPGuino for your fuel-consumption gauge needs. It'll work on just about any car with electronic fuel injection, except for a few very early ones.

-soD