For hypermiling in a standard transmission, is it okay to use engine braking with the

[Lambourne]

I'm trying to conserve gas by turning off my motor when I see the light in front of me turn red. I still like to use engine braking instead of the brakes. Will it be bad for my car's motor to leave it in gear and use the engine to brake while the ignition is turned off? Vehicle is a '98 Mazda B2500 (Ford Ranger) fuel injected, standard transmission.

Thanks in advance.

[Gasoline Fumes]

It should be fine on a fuel injected engine as long as you're sure that the fuel is being cut off.

[PaleMelanesian]

It's probably already shutting off the fuel flow so you don't need to turn off the ignition. Test to see: Engine brake with ignition on, then turn ignition off and see if there's a change in the amount of braking. If there's no change, leave it on and let the automatic DFCO (deceleration fuel cut off) do its job.

[t vago]

Sometimes, you'll be able to tell if your vehicle enters DFCO while engine braking. For instance, on my Sebring (which is a stick-shift), when I initially enter engine braking, the car will slow down. After about 2 seconds or so, I can feel a slight jerk, and the car will slow down a little faster. Along with that, my O2 sensor gauge will go really lean along with that slight jerk.

[PaleMelanesian]

On mine the DFCO is immediate, but I can feel when it turns the fuel back on at about 1100 rpm. The braking stops and the car "surges" forward slightly.

[Diesel_Dave]

If you motor the engine with the ignition on won't it start?

If you motor the engine with the ignition off won't it lock up the steering?

[IsaacMTSU]

I engine brake with the key off all the time. My CRX is the same as PaleMelanesian's, pretty much any time you engine brake over 1000 RPM, it cuts fuel. You can feel it surge slightly when it slows back to around 1000 RPM. Also, the steering isn't locked on mine until you click it back the second time, but on my S-10 it locks at the first turn back.

[PaleMelanesian]

The ecu is smart enough to realize it's engine braking and it shuts off the fuel injectors. Various makes and models have different conditions required. Hondas are usually >1000 (or 1100) rpm. Some have speed requirements, or wait a second or two first, like t_vago's dakota. The wheels are driving the engine in this case.

[Smokeduv]

Originally Posted by IsaacMTSU

I engine brake with the key off all the time. My CRX is the same as PaleMelanesian's, pretty much any time you engine brake over 1000 RPM, it cuts fuel. You can feel it surge slightly when it slows back to around 1000 RPM. Also, the steering isn't locked on mine until you click it back the second time, but on my S-10 it locks at the first turn back.

I always wondered why the engines makes such a strange thing when engine braking and gets to 1000 then goes to 800.