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The Fiesta achieves its best-in-segment fuel figures thanks to a host of fuel-saving technologies not normally seen at this price level. To increase fuel economy, Fiesta features a new 1.6-liter Duratec¨ engine with Twin Independent Variable Camshaft Timing (Ti-VCT) that delivers 120 horsepower, an aggressive deceleration fuel shutoff and an engine accessory drive system that improves efficiency by reducing the energy it takes to power the air conditioner and alternator.

I love the electric steering and knew it was not driven directly by the engine, but the above excerpt from the Blue Oval Blog talks about "engine accessory drive that improves efficency by reducing the energy it takes to power the air conditioner and alternator"

I have been under the hood, and it has a huge alternator, clearlyl to help power the EPAS, but I have not got under the car to see where the A/C compressor is, or how it is driven.....also, had never heard of the deceleration fuel shutoff.....

Anyone help me out here?
 

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Sweet!

Fancy phrase for stop-start that's starting to pop up on other vehicles.

When you're stopping (rather, when the car thinks you're going to stop), the fuel flow is cut off (so almost shutting the engine off). It automatically restarts when you're going to accelerate (get moving again).
The Fiesta is just a smart little car!
 

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Some of the new alternators have a clutch in them. They actually free spin when they are not needed. Which of course helps reduce the drag on the motor. The fuel off is turned off when coasting or when your foot is off the pedal. No use in using fuel to slow down;)
 

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DFCO (Deceleration Fuel CutOff) has been on all fuel injected cars/motorcycles since the mid-80's. Several seconds after you let off the gas, the computer shuts off the fuel injection (to cut emissions, mainly). The injection is turned back on when the rpm drops below a certain speed (varies with vehicle, but somewhere around 2000 rpm or less).
 

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DFCO (Deceleration Fuel CutOff) has been on all fuel injected cars/motorcycles since the mid-80's. Several seconds after you let off the gas, the computer shuts off the fuel injection (to cut emissions, mainly). The injection is turned back on when the rpm drops below a certain speed (varies with vehicle, but somewhere around 2000 rpm or less).
Here's a question on this:

I put a ScanGauge on my Fiesta, with two of the displays showing instantaneous MPG and GPH (gallons per hour).

In a previous car, when coasting in gear, I would see MPG go to 9999 and GPH go from some non-zero number to 0.0, indicating that no fuel was being injected. Once RPM reached idle level or the clutch was depressed, MPG would go to some other number (if still moving; otherwise 0) and GPH would go to whatever it was at neutral idle.

But in the Fiesta, when coasting in gear, I would see MPG go to some high number, but not 9999, and GPH go to 0.2 to 0.4 instead of 0.0, indicating that fuel was still being injected. This seems to indicate that it isn't actually completely shutting down fuel injection when coasting in gear, even at RPM above idle.

Anyone else with a ScanGauge or other OBD-II scan tool notice this?
 

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Personally, I think that something about the Fiesta is befuddling the Scangage. I've noticed that mine will show 9999 for way too long, sometimes when the car is obviously idling or under a load (I've already adjusted the cut-off to 14). This is obviously going to mess up the MPG calculations
 

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I don't know if this is relevant, but I heard that in newer cars, (and maybe only manuals trans), the computer puts a limit on how quickly the engine slows down in order to reduce emissions. In other words. when you quickly lift your foot off the gas, the computer gradually reduces the fuel flow so the engine slows down more slowly than it would it your foot was controlling the gas directly.
 

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I don't know if this is relevant, but I heard that in newer cars, (and maybe only manuals trans), the computer puts a limit on how quickly the engine slows down in order to reduce emissions. In other words. when you quickly lift your foot off the gas, the computer gradually reduces the fuel flow so the engine slows down more slowly than it would it your foot was controlling the gas directly.
Yes. This is true. One of the issues that developed when emissions regs tightened up several years ago was the problem with unburned hydrocarbons. The HC issue will rear it's head under conditions where you have a deep throttle/high rpm condition and then lift off the throttle to idle or shift. The fuel was still being sent through but demand had dropped. anyone who has driven newer cars in the last few years has noticed how the engine seems to race when cold started and then gradually drops to idle in around a minute or so. This is an emission control strategy. a few years ago this level of engine control was extended to include pretty much any deep throttle application at any engine temperature.Many gearheads did not like this because it ruined the zippy feel or sharpness of response that we all love so much in a performance car. The fact that all this stuff is required and also tends to help optimize(in some conditions) performance and fuel econ' is what makes me very leery about performance oriented "reflashes" or intake design rethinks from the aftermarket. 120 hp and 38mpg from 1.6 litres that has the great drivability of the Fiesta in stock trim would have been UNHEARD of just a few years ago! Believe me, I love performance upgrades. every vehicle I own except my DOHC Sable wagon has one kind of enhancement or several! I also understand the reality of not being able to achieve 110% if all ya got is 100% to give. I think Ford did an exceptional job!
 

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I think Ford did an exceptional job!
Agreed! The test drive of a Fiesta I took two weeks ago literally blew me away with regards to engine power and responsiveness for such a small car. The 1.6 L engine in my 1984 Ford Escort made a whopping 68 horsepower delivered through a 3-speed automatic. The Fiesta makes 120 horsepower from the same size engine, and I will be driving it with a 6-speed dual clutch automatic.

My, how times have changed!!
 

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Here's a question on this:

I put a ScanGauge on my Fiesta, with two of the displays showing instantaneous MPG and GPH (gallons per hour).

In a previous car, when coasting in gear, I would see MPG go to 9999 and GPH go from some non-zero number to 0.0, indicating that no fuel was being injected. Once RPM reached idle level or the clutch was depressed, MPG would go to some other number (if still moving; otherwise 0) and GPH would go to whatever it was at neutral idle.

But in the Fiesta, when coasting in gear, I would see MPG go to some high number, but not 9999, and GPH go to 0.2 to 0.4 instead of 0.0, indicating that fuel was still being injected. This seems to indicate that it isn't actually completely shutting down fuel injection when coasting in gear, even at RPM above idle.

Anyone else with a ScanGauge or other OBD-II scan tool notice this?
I have an UltraGauge and until I told it to try to detect injector cutoff, it would show consuming fuel during decel. My impression is that it is hard to configure a scan gauge to detect exactly when shutoff occurs. Does the ScanGauge have just an on/off for this function? The UltraGauge makes you put in a number (0 = don't detect cutoff) and if you put in too large a number it sees shutoff when you are clearly giving fuel, like you noticed too. The official number is supposed to be 11 (1.6 L * 7) but I've cut it to 5 so it shows cutoff at more plausible times [it looks like "5" is too pessimistic, but "7" is close to what the onboard display thinks]. When cutoff is detected, it shows 0.00 gallons per hour of fuel consumption.

Detecting cutoff is also making it more optimistic than reality for gas mileage, so I'll have to do some additional calibration before this is of any real usefulness.
 
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