Fuel consumption. Summer vs Winter

[alex_rsa]

Has anyone else found a big discrepancy between Summer and Winter fuel consumption?

I drive exactly the same route at the same time and in Summer last year I got 200 miles between refuels. It will take somewhere between 21.0 -21.5 litres.

In Winter I ran out twice before I got to 190 miles. That means nearly 23 litres. I thought there was actually something wrong with the bike.

Now we are back in Summer my consumption is back to normal.

We are talking about 10% difference and it is very consistent.

Edited - I have owned the bike nearly 8 years but it only the last 2 that my Summer and Winter riding is so consistent.

 

[duckspeed]

Maybe cold engine for longer needs longer enrichment period

 

[Deleted account 190920001]

Cold weather, cold engine and it takes a lot longer for them to get up to temperature. All the time they are cold there is more fuel getting pumped in, on choke if you like. It gets worse if you only do lots of short journeys. 10% isn't bad, I am at least 20% less with the car in the winter.

 

[Wreford Miles]

Oh come on....

If you're going to ask that question at least provide some decent data

How long is this regular trip, how often do you do it for starters.

 

[Pukmeister]

A cold engine needs more fuel to make the same power as an engine at the correct operating temperature.

Laws of physics, Otto cycle, blah blah blah....

 

[Greenman14]

Yes, all my cars and bikes over many years do this to some degree. Reasons as above, longer to warm up. My air cooled Multistrada used to take about 30 miles for the oil to warm up properly- I know because it had an oil temperature gauge. Cold engines use more fuel and it takes longer to warm up in winter.

Don't worry, summer will be along soon.

 

[alex_rsa]

My trip is 40 miles a day so plenty of time to warm up (20 miles each way). The trip is identical every day except for more traffic on some days. The traffic does make a small difference of about 2% increase/descrease in consumption. This is noticiable during school holidays when the traffic is quieter.

I have noticed that the idle speed is lower and more consistent now the weather is warmer...maybe whatever is controlling the enrichment circuit is being to generous in Winter.

 

[Bendy toy]

In general air cooled engines are over cooled in winter because that is less harmful than having them over heat in summer. However its likely to have been over compensated to cope with extremes we (almost) never get in UK. Maybe a remap will help. Also maybe some means to adjust whatever parameter the ECU uses to sense engine temperature for mixture control.

In the old days we would see cars with leather/vinyl flaps on the radiator grille to stop it over cooling. Maybe we need wally flaps for the front of the engine to reduce the overcooling effect. But before doing that the engine would need at least some exhaust gas temperature sensing so it wont over heat. Thermocouple spark plug washers would be ideal but there is no space to run the wires past the unit coils.

Full liquid cooling (as in a car or Japanese bike) can maintain the engine closer to an ideal temperature but its heavy and complex. In the end this is what we pay for the simplicity of air cooling.

 

[ianran]

What is "Summer" ???

 

[LBL]

I ride at least twice a month to Bouillon in the Ardennes, i rode there 2 weeks ago and the temp did not get above 6 degrees, i was with a mate and we rode at a reasonable speed and got 45mpg

I rode there alone on thursday, albeit a quicker pace and it was 31 degrees and got 41.5mpg

In october last year i got 38.5mpg for the same trip.

the only reason i take any notice is that its 290 miles door to door and at 38.5mpg i wouldn't make it without a fill up..

 

[Pete O Static]

Cold air is more dense than warm air and cold fuel is more dense than warm fuel. Theoretically, you should be able to carry more fuel when it is cold. This is why most gas pumps are calibrated to 15C which is a standard temp.

Having said that however, I thought that BMW EFI compensated for volume delta vs temperature just as it does for altitude change.

I haven't noticed any obvious change in mileage on my bike between seasons.

 

[Neil W]

From experience older mechanical fuel injection systems (Bosch k jetronic) never varied in fuel consumption from summer to winter ( seven Scirocco GTI's , GTX's and Scala injections)
Newer electronic fuel injection do, once vw went over to Bosch digifant fuel injection our cars consumption would on average rise by 15 % in cold weather (x2 Passats a GT and GL plus a Corrado 16v).

 

[Rasher]

Don't worry, summer will be along soon.

You missed it, we had it about 3 weekends ago, it's Autumn again now

 

[n0ct0]

My onboard computer never budged from 46mpg over 2500 miles during the winter. Since it got above about 10C it's been heading up to 48mpg and still rising. All over the same routes, usually about 200 mile day rides mixed motorway, A and B roads averaging about 50mph over the whole trip.

 

[Belper phil]

Fuel summer / winter

In Winter I ran out twice before I got to 190 miles. That means nearly 23 litres. I thought there was actually something wrong with the bike.
Now we are back in Summer my consumption is back to normal.

Colder temps - increased friction, engine has a tougher time (as stated in previous posts)

Warmer outside temps - less friction, engine not under as much pressure to achieve results. Only my 2p worth, but this is how it works with modern commercial vehicles

 

[n0ct0]

http://www.metrompg.com/posts/winter-mpg.htm

Given that a motorcycle and rider is as aerodynamic as a falling wardrobe I would guess that the increased drag will affect bikes more than cars.

 

[CC Mac]

Summer 48.5 - 51 Winter 44.5 - 48.

 

[Bendy toy]

Now it's summer, mine might be giving me another litre's worth from a full tank. But the trip computer shows the same 47mpg even after resetting.

But with clean(er) summer roads, I might be riding it harder.

 

[fireman]

Just reading about your mpg results..on a 1200gs 2007 . I did a trip up to penrith via all the back roads and taking it steady. From a fully brimed tank i needed 14.8 liters to refill after 187 miles. Amazed i checked the computer for mpg. 67 mpg i jest you not. I did the quick option home, 106 miles down the m6 at a constant 85-90 and my mpg was 42. I think these bikes vary dependent on your right wrist. I ride all year through and havnt ever noticed tempriture making a differance..

 

[MiGSel]

I think the main cause is not friction.

Cold air is more dense and hence contains more oxygen. This is detected by the sensors and fuel injection allows more fuel to be injected, to obtain the same fuel/oxygen mixture for optimal combustion.

So cold weather means more fuel AND more power. You should also notice that your bikes pulls stronger in cold condions. Which is a shame of course, since we don't want more power when tarmac & tyres are cold and there may be ice or snow around.