Fuel consumption while coasting
03-21-2011, 02:15 PM
#42
I think you will find that as fuel prices go up, and consumers worry more about mileage, OEs will start to provide more aggressive DFCO.
My 07 auto cts enters it, what I would say is "fairly often", I wish it would more though.
Really the only downside I see to it is, that when it engages, an observant driver/passanger can feel the slack (backlash) in the drivetrain as the vehicle switches from delivering power, to receiving. Coming back on is a near seamless event in my experiences.
As far as my camaro goes, I'm not overly concerned with mpg... but at the same time, why waste gas? Not to mention with headers and full length exhaust, it sounds cool when it enters DFCO
My 07 auto cts enters it, what I would say is "fairly often", I wish it would more though.
Really the only downside I see to it is, that when it engages, an observant driver/passanger can feel the slack (backlash) in the drivetrain as the vehicle switches from delivering power, to receiving. Coming back on is a near seamless event in my experiences.
As far as my camaro goes, I'm not overly concerned with mpg... but at the same time, why waste gas? Not to mention with headers and full length exhaust, it sounds cool when it enters DFCO
03-21-2011, 02:48 PM
#43
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So does anyone have any good guesses as to why the auto F-bodies dont have this feature effectively enabled like the manuals do ?
Honestly, i doubt it really effectively increases mileage much at all since it' would barely be active even if it was enabled and it's active only when the engine would be using the least amount of fuel anyway.
If you have programming that allows you to cutoff injectors and spark then why is it not possible to cutoff individual cylinders during cruise in an LS1? When i got my 92 camaro with an L03, the spark plug wires were fried on 3 or 4 of the cylinders and it ran pretty much the same after I fixed them (much less power but it was still pretty smooth)... Seems like cutting off a couple cylinders during cruise would be far more effective at increasing mileage than only playing with coasting.
Honestly, i doubt it really effectively increases mileage much at all since it' would barely be active even if it was enabled and it's active only when the engine would be using the least amount of fuel anyway.
If you have programming that allows you to cutoff injectors and spark then why is it not possible to cutoff individual cylinders during cruise in an LS1? When i got my 92 camaro with an L03, the spark plug wires were fried on 3 or 4 of the cylinders and it ran pretty much the same after I fixed them (much less power but it was still pretty smooth)... Seems like cutting off a couple cylinders during cruise would be far more effective at increasing mileage than only playing with coasting.
03-21-2011, 03:04 PM
#44
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The problem with only running on a few cylinders are different than the problems involved with running on no cylinders.
Also, in my all stock but no cats (but no tuning) A4 setup, I have noticed while driving around that after a moment of decelerating in drive from 2.5k-3.2k or so my engine seems to brake better and I get this growling noise from the back of the car which I always assumed was the exhaust popping. Would any of that be caused by DFCO or is that just normal?
Also, in my all stock but no cats (but no tuning) A4 setup, I have noticed while driving around that after a moment of decelerating in drive from 2.5k-3.2k or so my engine seems to brake better and I get this growling noise from the back of the car which I always assumed was the exhaust popping. Would any of that be caused by DFCO or is that just normal?
03-23-2011, 08:10 AM
#45
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After seeing those charts and reading up a bit, I got out the scangauge manual. The only change I needed to make was to put the TPS setting at the appropriate number. It was defaulted to 24 and I set it to 4 above zero throttle, which was zero. It's 17 on the 96 F150 I-6 that I tested on first.
I also selected to watch the GPH (gallons per hour) and Open/Closed loop.
In the truck I was able to watch it go into open loop and 0.0 GPH. At that time the MPG went to 9999. The way I could get those readings was to coast down hill for a bit. It was not presented very often, but putting it in 4th instead of 5th to coast did the trick consistently.
In the Camaro on the way to work this morning, using the correct TPS setting, and watching for Open/Closed loop and GPH, I was still unable to get into DFCO. The coasting MPG did go up to 151, though. Also, I noticed the GPH was about the same during the coasting at 140+ MPG as at idle...about .46 GPH. Idle produces about .46 to .50 GPH.
My car is a 98, has a ported TB, a cut off EGR nozzle, but no other changes that I can think of that would alter it enough to make the DFCO points difficult to reach.
Dunno. The same MPG tricks work for every car they get tried on. DFCO could be useful, but doing the same things without getting DFCO will still be the best way to maximize your fuel purchases. It's fun to watch DFCO kick in, but not anything to cry over or get upset about.
Happy motoring.
03-23-2011, 11:39 AM
#47
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In the Camaro on the way to work this morning, using the correct TPS setting, and watching for Open/Closed loop and GPH, I was still unable to get into DFCO. The coasting MPG did go up to 151, though. Also, I noticed the GPH was about the same during the coasting at 140+ MPG as at idle...about .46 GPH. Idle produces about .46 to .50 GPH.
My car is a 98, has a ported TB, a cut off EGR nozzle, but no other changes that I can think of that would alter it enough to make the DFCO points difficult to reach.
My car is a 98, has a ported TB, a cut off EGR nozzle, but no other changes that I can think of that would alter it enough to make the DFCO points difficult to reach.
It may also be our '98s have have slightly different tuning, since the '98 PCM isn't quite the same as the '99+ (though I never noticed this on my '00 car either). Next time I dig my scanner out, I'll try looking at this on my '02 car (which is stock, other than an air lid and muffler). I highly doubt that I'll be able to get it active though, since the only thing even close to a hill around here is an expressway overpass.
03-23-2011, 12:37 PM
#48
the 96 F150 I-6 that I tested on first.
I also selected to watch the GPH (gallons per hour) and Open/Closed loop.
In the truck I was able to watch it go into open loop and 0.0 GPH. At that time the MPG went to 9999. The way I could get those readings was to coast down hill for a bit. It was not presented very often, but putting it in 4th instead of 5th to coast did the trick consistently.
I also selected to watch the GPH (gallons per hour) and Open/Closed loop.
In the truck I was able to watch it go into open loop and 0.0 GPH. At that time the MPG went to 9999. The way I could get those readings was to coast down hill for a bit. It was not presented very often, but putting it in 4th instead of 5th to coast did the trick consistently.
