Thread: Neutral Coast Not So Great for Fuel Economy

Interesting, I'll keep that in mind for harder compound tires. Mine are way too soft at the moment.

Sucks that ECU Talk clears that information, ScanGauge does keep the trip information and tank information.

I'm assuming ECUTalk averages out the whole trip's gas mileage or does it just give out instant numbers?

Do you never write down how many gallons you fuel up over how many miles you drive?

I never really drive until tank is empty, I usually drive 30-60 miles then fuel up...

i think you are obsess man... lol

An automatic trans is a different animal. You can only get "engine braking" while in 4th gear (in a 4 speed), or if you manually select one of the low options. The auto transmission is designed with one way clutches that overrun when coasting. Basically the engine returns to idle instead of engine braking.

As long as you are engine braking in 4th gear in your automatic, you are doing the same thing as a manual transmission is. 4th gear is the only one with the engine-braking qualities. You will notice this when driving the car. The car will coast when you let off the gas in 1st, 2nd, and 3rd. But when you are in 4th, the engine rpms will stay higher than idle and the vehicle will start slowing down, thus engine braking is achieved.

When the car sees an engine braking condition, the computer temporarily shuts off the fuel injectors. With no load, no throttle open, and an engine speed higher than idle, the computer turns off the injectors. That is how you will burn less fuel at 4-5k rpms than at idle. The simple answer is: you simply aren't burning any fuel at all

^^^ Whoa! Didn't know that!

Maybe this is a reason why automatics usually get worse gas mileage?

Well, that, and the fact that they have substantially more pumping loss from the torque convertor.

Ahh so more drive terrain loss = more rotating mass = less efficiency thus less power and MPG's.

I'm still wondering if the a lighter flywheel makes the FWD car have less then 15% power loss.

so when did car companies start tuning the injector shut off while coasting into ECUs? i have real world evidence that nuetral coasting gets me better mpg. im driving a 2000 G20t. there were only a few years of sr20's after 2000 so this neutral coast Vs. high gear coast argument probably does not effect this forum.

Almost all fuel injected cars have an injector pulse of 0ms while coasting on gear.

I also noticed that if you are in gear and start breaking little more then lightly, then the MPG will turn to 99999 on the ScanGauge (so might be the injectors turning off)

i believe its called DFCO (Deceleration fuel cut off)