I've previously ridden carbed bikes. A buddy tells me that on a fuel injected bike the gas mileage gets worse as the weather gets colder....true?...why?

 

The air should be denser, but I doubt you will notice much difference, especially as the O2 sensors will cater for any atmospheric differences.

WB

 

I have read that on the Harley EFIs the default air/fuel mixture in cold weatheris 12 to one, which is pretty rich. I don't know at what enginetemperature the default goes off, but think of it as riding with your choke on until it does.

 

Far as I have seen.. not true .. same mileage hot or cold ...actually colder temp is better re mpg..and the motor pulls stronger in cold weather.. no doubt..

If you want less mpg get a header, installa fuel program and a/c..
more air = more fuel

 

I think also there is a definite difference in "cooler" weather, and "cold weather." A air cooled motors definitely run better in cooler, moist air, but before EFI theyran like crap in cold weather until fully warmed up. With a carbed bike, you can usually shut the choke off as soon as you're rolling down the road--the computer is now controlling that.

 

Something not mentioned yet which is probably pertinent is in the northern climates the fuel is blended differently during the winter for better starting, and this usually causes a slight loss in mileage per gallon. I don't know whether that has yet kicked in or not. I know my last few tanks have shown poorer mileage.

 

I've read the same thing, that A/F is 12:1 when the engine is open-loop mode in some areas (like idle), and open-loop is the default until it reaches operating temperatures. Of course, those of us with PCIII's (not the EX version) run in open-loop mode at all times.

Last winter my mileage was about 10% less than this past summer, and I will be experimenting with my PCIII map to compensate for this as winter approaches. I have already leaned the mixture 5-10% over default (zero PCIII values) below 40% TP and the bike runs fine, except for some slight surging when cold. Heat will not be an issue this winter, and I will watch performance, any hint of pipe discoloration, and oil temperature as the experimentation progresses. So far so good, but haven't done any mileage checks since my last tweak. I really want a A/F gauge--a real one that shows the actual ratio, not an LED display--but I can't justify spending >$200 on one. There should be a way of determining A/F based on the voltage output of the O2 sensor, but I have not found a conversion chart yet. I still have one O2 sensor installed an could use it, although narrow-band sensors like the HD unit is limited in the info it can provide. Measuring the voltage of a wide-band O2 sensor like the Bosch LSU4 series would be much better. Does anyone know of such a conversion chart?

Anyway, this EFI bike can't begin to attain the mileage levels I did with my old carbed Evo with a Thunderslide kit installed. I could push the choke in a block from my house, and although it would not idle and would run rough 'til warm, the mileage was good even in winter. The EFI will hold cold mode until the bike is warmed up, which means a richer mixture and lower mileage--and you really have no control over that unless you can figure out how to fool the head-temp sensor into reporting the engine is at operating temperature. PCIII tech support doesn't know these values or I'd have something to go on, and HD certainly won't tell me anything. Even so, I'm not sure the bike would run in hot mode when cold. With a choke you could pull it out as needed, and any tweak you make of this nature on EFI may trigger a fault code.

I'm rambling here, still trying to maximize mileage on this bike. The bottom line is that an air-cooled, EFI engine has two strikes against it in the mileage game. First, it takes forever to warm up, especially in winter, and cools down rapidly--so it is in cold mode much longer than a water-cooled engine, which has much better control over engine temps. I think we'll have to live with this fact, but I'm still thinking about ways to maximize mileage. Right now I'm at 40 city, 50 highway (55 mph), 47 highway (65 mph), and 40 at 70-75 mph with a strong headwind (measured coming back from AR two weeks ago). These were all on my richer summer map. All of these figures are acceptable except city, and I'm working on that.

 

air molecules are more dense, more air more fuel. Runs much longer in warm up mode. I get 43 in summer and around 39-40 in winter.[/align]did'nt believe huh?[/align]

 

Stored gasoline undergoes less expansion in the winter and you get more for your $ than in the summer.

 

I didnt buy it for mileage.
But thats just me