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lagerdrinker
12th February 2007, 00:26
does fi have fuel cut off on hard decel or is it proportional to tps and map at all times? just wondering, thinking why mpg isnt improved over carbs (from what ive read)

whittlebeast
12th February 2007, 13:17
Generally this is the logic used on the Over-run fueling.

IF the engine temp is up to operating temp (or close)

AND IF the MAP is 3 KPA below the lowest ever seen at idle

AND IF RPM is 300 or more above idle (keeps the vehical from lunging when fuel is reintroduced)

AND IF throttle is at the idle (fully closed) position

AND IF all these conditions has been like this for more than 1.5 sec (keeps this from being noticable on shifts as then happen faster than this)

THEN compleatly stop ALL fuel flow


This will compleatly stop all over-run backfiring thru the exhaust on downshifts.

I have no idea if Harley does this as they won't allow you to see the base code and MAPs even with the so-called tuners. The other thing that realy helps this is having all the MAPs real close to 14.7:1 when the motor is in this condition. Overly lean or overly rich will give this same feel and o2 sensors are compleatly useless once a mis-fire starts happening. I have not noticed any of this on my 2007 Sportster. I would bet Harley is not doing it. Once we get these things on Megaquirts, this will all be totaly under your control.

hope this helps

AW

Moved On / My Own Choice
12th February 2007, 13:58
But isn't the EFI fuel economy better on highway, worse around town?

I figured (stupid seat of the pants guess) that they were richer through the accelerating portion of the throttle range and tended to lean out at steady throttle...

williard952
12th February 2007, 14:43
comparing my '91 to the '07, the new bike
is marginally better all around. 49-51 for the
'91 and 51-53 for the '07. I'm a 7mi 35MPH
drive from home to work, about 1 MI of in
town. Doesn't seem to change much although
when the wind is at my back, I've seen 60MPG
on the old bike.

-W

blastoff99
12th February 2007, 14:45
As for fuel economy, I don't know about "around town" yet, but it sure ain't great anywhere else. My bike is still very new, under break-in, and I'm only taking it out when I can get a good 40 - 50 miles in. I generally take back roads with speed limits of 50mph. I vary the speed, and vary the load, but all in all it should be ideal riding for fuel economy. 40 - 42 mpg seems to be all I can get. Given what H-D said in the brochure (57, I think), I expected to be seeing at least 50mpg. If I don't, I'll be mad. I've always gotten exceptional mpg on everything I've ever driven / ridden, so I know how to do it. It ain't working here.

Hijack off.

whittlebeast
12th February 2007, 16:12
Remember that a feedback closed loop system with narow band O2s can only home in on 14.7 AFR. Great for EPA but not so good for cruse gas milage. A well tuned carb may actually get better cruse milage as it may be jetted for 16:1 AFR. EFI is just far better at getting everywhere at the AFR that the tuner wants. Carbs are hopeless at doing this.

AW

Moved On / My Own Choice
12th February 2007, 16:20
Remember that a feedback closed loop system with narow band O2s can only home in on 14.7 AFR. Great for EPA but not so good for cruse gas milage. A well tuned carb may actually get better cruse milage as it may be jetted for 16:1 AFR. EFI is just far better at getting everywhere at the AFR that the tuner wants. Carbs are hopeless at doing this.

AW

That doesn't make sense if specs are anywhere near accurate.

883

Carb vs. EFI

57 hwy / 48 city vs 59.7 hwy / 45 city


1200

Carb vs. EFI


52 hwy / 45 city vs. 57.1 hwy / 42.4 city


At least the SPECS say the EFI models are slightly more efficient on the highway, and slightly LESS efficient around town.

whittlebeast
12th February 2007, 17:23
My point is that EFI is not always better at any one thing. It is always better at doing everything. Carbs just can not be tuned everywhere. THat is why you just dont see them on anything new. Lawn mowers and NASCAR is about it.

AW

williard952
13th February 2007, 14:44
Seems like I was getting just shy of 50,
like 47-48 on the first few tanks. Speed
always changing, WOT blast occasionally.
Once through break-in the first run at steady
throttle was an immediate jump in MPG.
Constantly improving...

Working on new toy for this spring/summer...
"Loop indicator" to tell when FI goes closed loop.
Probably end up with some type of logging to
get a handle on what it takes on the '07 to get
it to get good mileage (probably have to get one
of those ball caps from Ron-Jon's with the
salt&pepper pony tail so I look the part of some
old fart riding his shiny new bike).

whittlebeast
13th February 2007, 19:39
A simple Ricer bouncing LED display will tell you when it is in closed loop. If the lights go nuts bouncing back and forth, you are there.

AW

Drew1200c
14th February 2007, 10:07
gas can be a factor too, different companies use different additives so some brands of gas could get better MPG than others, and mixing different brands together might also have an effect.

lagerdrinker
14th February 2007, 11:30
[QUOTE=williard952;633804]
Working on new toy for this spring/summer...
"Loop indicator" to tell when FI goes closed loop.
QUOTE]

i know you didnt ask but i think its a waste of money. money that can go to more gas. figure even the cheapy guages like whittlebeast mentions is like 30.00 and you want to see 5mpg more...you do the math.
for the computer to go into loop the 02 sensor must reach temp to start feedback. are the 02 sensors heated or single wire?
i wonder how long before the moco adds egr to aid in mpg?

williard952
14th February 2007, 14:17
jim sez:
> i know you didnt ask but i think its a waste of money.

Just like the bike, the indicator is about the journey,
not the cost or utility. Another aspect of this little
project is to come up with the cheesiest tach
possible, something that just shouldn't show up
on a sportster. So I found this $30 SUN tach
down at the auto parts store, and if I can find
the right bits of information from the bike, it will
be a MPG meter instead of a tach. I didn't
realize how much fun having an OBD-II port on
a bike could be :-). The boy (17 yr old) wants
to put one in his car and have the coolest gauge.

-Willy