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Old 05-02-2012, 06:56 PM   #121
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Quote:
Originally Posted by GoShockers View Post
The Focus does not go into DFSO in neutral. You must be in gear and have sufficient momentum to power the engine and accessories with no fuel.
Yes, being in neutral prevents the car from going in DFSO -- I thought I said that...


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Old 05-02-2012, 06:57 PM   #122
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Quote:
Originally Posted by kam327 View Post
Careful though, isn't the PCU/ECM thingy (and therefore the Scangauge) highly innacurate at calculating fuel flow at low RPM's?
Perhaps, I have no practical way to know that for sure.


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Old 05-02-2012, 07:42 PM   #123
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So your using the scangauge (I thought you had a profesional scan tool) to tell you when your in decel fuel by the MPG telling you its using no fuel ("no fuel being burnt while in motion) ???

So you cannot see things like
Fuel source
#/min fuel
Injector Pulse width
Etc


Yes I know what CL and OL is , I do over half the tuning on the Foci on this Forum

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Old 06-27-2012, 08:20 PM   #124
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I used my recently bought Scangauge E to test out the coast in gear vs neutral debate. It seemed to me coasting in gear with DFSO must be more economical. But...

I got up to 45 mph on a deserted country road and then when 0.5 miles from a stop sign (confirmed it on google earth) I took my foot off the accelerator and reset the Scangauge's trip data (and therefore avg mpg). By the time I reached the stop sign I was going 12 mph and the avg mpg readout said 80 mpg.

Then I did the same thing but shifted into neutral while resetting the trip and by the time I reached the stop sign I was doing 21 mph and the avg mpg calculation said 111 mpg.

I repeated both in the opposite direction and got similar results.

I'm guessing that getting to the stop sign quicker in neutral is more of an advantage than DFSO activating at first but then deactivating at the lower speeds and really dragging down economy in those final seconds.

I still think coasting in gear is better in most city or suburban driving situations (where you don't have enough room to coast all the way down to <20mph) but next time I'm on an open road with a good half mile before a definite stop and no chance of having to speed up again, I'll shift 'er into neutral.....
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Old 06-28-2012, 07:35 AM   #125
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Quote:
Originally Posted by kam327 View Post
I used my recently bought Scangauge E to test out the coast in gear vs neutral debate. It seemed to me coasting in gear with DFSO must be more economical. But...

I got up to 45 mph on a deserted country road and then when 0.5 miles from a stop sign (confirmed it on google earth) I took my foot off the accelerator and reset the Scangauge's trip data (and therefore avg mpg). By the time I reached the stop sign I was going 12 mph and the avg mpg readout said 80 mpg.

Then I did the same thing but shifted into neutral while resetting the trip and by the time I reached the stop sign I was doing 21 mph and the avg mpg calculation said 111 mpg.

I repeated both in the opposite direction and got similar results.

I'm guessing that getting to the stop sign quicker in neutral is more of an advantage than DFSO activating at first but then deactivating at the lower speeds and really dragging down economy in those final seconds.

I still think coasting in gear is better in most city or suburban driving situations (where you don't have enough room to coast all the way down to <20mph) but next time I'm on an open road with a good half mile before a definite stop and no chance of having to speed up again, I'll shift 'er into neutral.....
This is all interesting. And I've come to the same conclusion myself.

In Test mode on my manual, it appears that the car starts burning fuel again under 25 mph even if you're coasting in gear. Is it possible that it burns less fuel than it burns at idle? Maybe. I don't really have to the tools to tell, and I doubt the difference is enough to seriously matter.

On the 5MT, 25 mph is right at the bottom of 4th gear. If I'm coming to a stop, I usually slow down (coast if possible but brake if needed) to ~25 mph in 4th, then pop in the clutch for the rest of the stop. I figure this is a decent compromise for fuel economy, clutch wear, and brake wear.

Anyway, I think it's a pretty esoteric point except for the theory discussion to talk about whether you should coast in gear to 25 mph or 12 mph. Maybe it's a valuable point if you're trying to go from 44 mpg to 45 mpg... but, really... You're not commonly going to be able to coast to 12 mph on public roads. You know, at some point as you coast in neutral, you're going to be moving so slowly that burning the fuel to idle the engine at that vehicle speed is actually less efficient than just driving the damn car. :)

And I don't have all day to wait for the car to slow down on its own either. ;)

Good post.
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Old 06-28-2012, 07:41 AM   #126
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Quote:
Originally Posted by Pretherius View Post
Anyway, I think it's a pretty esoteric point except for the theory discussion to talk about whether you should coast in gear to 25 mph or 12 mph. Maybe it's a valuable point if you're trying to go from 44 mpg to 45 mpg... but, really... You're not commonly going to be able to coast to 12 mph on public roads. You know, at some point as you coast in neutral, you're going to be moving so slowly that burning the fuel to idle the engine at that vehicle speed is actually less efficient than just driving the damn car. :)
Yeah I'm going to do it again this weekend but wait longer to start coasting so that I end up at the sign still doing at least 25. Then it'll be of more real world use.
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Old 05-22-2019, 08:59 PM   #127
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I have a 2014 focus st and Injectors 1 or 4 will shut off no matter what tune, no tune, or if I'm on the gas 1/4 throttle or full throttle! anyone have a similar problem?
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Old 05-23-2019, 07:33 PM   #128
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Foci-philes:

I'm a little late to this party but 'coasting fuel shut-off' (CFSO) is a parameter in most calibrations. I can only speak about my '98 Mustang GT but, generally, it applies to much younger model years.

If you like engine braking then you want CFSO or DFSO as the case may be.

Using SCT's Advantage (ProRacer) program, you can turn it on and off based on load or RPM. And you can have it active in higher gears but not lower gears or all gears. You can turn if off.

The engine just pumps air (it does not have fuel to generate power) so engine braking is pretty good. If you like pops and crackles when decelerating then be aware that there are not while CFSO is active. (I'll take engine braking over the exhaust music while decelerating.) The engine goes way lean when the fuel is off so don't get excited when you see a yuge lean condition while in CFSO.

I don't know if tuners are allowed to adjust CSFO (use "the google" to find the EPA's suit against SCT and the stingencies now applied to tuners) but you can ask your tuner to add some in. Of course, you'll want to datalog so your tuner can add it where and when you want it.

That's about all I can tell you about CFSO. To paraphrase Martha Stewart, CFSO is a good thing. :D

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