Tuning for economy

[fljab]

I'm just curious, I see plenty of posts of adding PC's to smooth out performance both with and without other mods like aftermarket cans - but what if you want better economy? Longer tanks while on the interstate? Any thoughts?

My recent Michigan and back trip I kept pushing the tank to 250+, and was searching for the "ideal" speed that you can make decent time but also get good mileage, and on mine that seems to be ~75 mph. I guess I just got to thinking that maybe you could tune the bike for better mileage, or even "load a map" before a trip.

Long bike trips have a way of letting you think too much LOL...

 

[FJRay]

When I had the PCIII mapping done on a dyno which is the only way to get it just right I told the tech that I didn't want to lose my good milage at cruise speed. He left it just a little lean in that range and I still get 50 mpg if I am carefull. It's not quite as good here at altitude as it was at sea level but still does well. Keep in mind the dyno is great but it is only perfect at that moment in time and those conditions. Change days ,weather,altitude or any other thing and it all changes.

 

[joebiodiesel]

It should be pretty easy to do, and free to try.

Return the fuel settings to 0 at the RPM/TPS cells that match your cruise speeds.

Plug your O2 sensor back in.

Leave all the other settings alone.

REPORT BACK!



Joe

 

[fljab]

It should be pretty easy to do, and free to try.

Return the fuel settings to 0 at the RPM/TPS cells that match your cruise speeds.

Plug your O2 sensor back in.

Leave all the other settings alone.

You mean with a power commander? or can that be tuned without it?

I don't have one currently installed; still running stock...

 

[Bounce]

Increasing MPG means leaning out the A:F mix. As lean as it is already to meet EPA requirements, you need to know the impact of any changes you make to avoid ruining the motor.

If you're looking for increased MPG, then get a bike designed for it. Something like a 1-lunger 250cc might be a good place to start.

 

[charismaticmegafauna]

Increasing MPG means leaning out the A:F mix. As lean as it is already to meet EPA requirements, you need to know the impact of any changes you make to avoid ruining the motor.

I'm not so sure that any lean A:F ratios will do any harm to a (naturally aspirated) IC engine? (would running out of gas, an extremely lean situation, do any harm?)

Many lean-burn (higher A:F ratio than stoichiometric) combustion chamber designs have been done successfully -- driveability is, often, the main culprit with very lean A:F ratios.

If you're looking for increased MPG, then get a bike designed for it. Something like a 1-lunger 250cc might be a good place to start.

You're right there -- many 250s get 75 MPG.

 

[Checkswrecks]

I'm just curious, I see plenty of posts of adding PC's to smooth out performance both with and without other mods like aftermarket cans - but what if you want better economy? Longer tanks while on the interstate? Any thoughts?

My recent Michigan and back trip I kept pushing the tank to 250+, and was searching for the "ideal" speed that you can make decent time but also get good mileage, and on mine that seems to be ~75 mph. I guess I just got to thinking that maybe you could tune the bike for better mileage, or even "load a map" before a trip.

Long bike trips have a way of letting you think too much LOL...

Easier and cheaper to change your riding style.

Slow down, as power needed to overcome air resistance cubes as speed doubles.

Be as steady as possible. If I don't have much commuting traffic speeding up and slowing and can keep to about 50-55 mph (posted typically between 35-50) I can get gas milieage of around 51-53 mpg repeatably. Tires and brakes last forever too.

Keep the windshield down also for less air resistance.

If downhill and your forearm could take it, you could try hyper miling by holding the clutch in. My daughter knocks her stick Corolla into neutral downhill and has an overall average of 43 mpg!

Keep the tire pressures up. Low pressures are murder on mileage.

 

[fljab]

Increasing MPG means leaning out the A:F mix. As lean as it is already to meet EPA requirements, you need to know the impact of any changes you make to avoid ruining the motor.

If you're looking for increased MPG, then get a bike designed for it. Something like a 1-lunger 250cc might be a good place to start.

That's a way of not answering the question! I'm not talking about going to a 250, just getting better mpg on my FJR. I was just looking for some good tech talk from those smarter at this than myself to see if I'm missing something.

Your point of the AF being already leaned out quite a bit for EPA is a good one and well taken. I guess I was thinking of some way to tune it a little better - maybe at the expected speeds/rpm that you are in during interstate runs.

Who knows, this could even be a beneficial technical musing for some folks..........

 

[fljab]

Easier and cheaper to change your riding style.

Slow down, as power needed to overcome air resistance cubes as speed doubles.

If downhill and your forearm could take it, you could try hyper miling by holding the clutch in. My daughter knocks her stick Corolla into neutral downhill and has an overall average of 43 mpg!

Keep the tire pressures up. Low pressures are murder on mileage.

I partially edited your post; yes, riding style makes a difference for sure, and I experimented with different speeds like I said. I don't know how accurate the FJR computer mpg readings are and they tend to fluctuate, but saw that when I was in the hills with my AVCC engaged, when going downhill the reading would shoot abnormally high (upper 50's) to low when going uphill (30's).

As to the windshield; I keep it where I can look over it unless it's really wet then it goes to the top (CeeBaily+4+2). I'm surprised I got as good as I did due to all the extra lights I now have hung on the front of it!

 

[charismaticmegafauna]

... was just looking for some good tech talk from those smarter at this than myself to see if I'm missing something.Your point of the AF being already leaned out quite a bit for EPA is a good one and well taken. I guess I was thinking of some way to tune it a little better - maybe at the expected speeds/rpm that you are in during interstate runs.

Who knows, this could even be a beneficial technical musing for some folks..........

Usually, any more leaning of the A:F ratio (after the EPA gets its licks in) tends to show-up as driveability issues: flat spots in acceleration, surging, etc. That's not to say engines can't be tuned leaner -- they can, but it must be hidden from the operator (like shutting off the fuel when coasting (you won't notice...).

... don't know how accurate the FJR computer mpg readings are and they tend to fluctuate, but saw that when I was in the hills with my AVCC engaged, when going downhill the reading would shoot abnormally high (upper 50's) to low when going uphill (30's).

MPG read-outs are/have been (don't really know about Gen II FJRs) the digital equivalent of a vacuum gauge -- the higher the vacuum (requires lighter load and corresponding low throttle-valve opening) the less fuel mixted with the air (there's less air being used -- you see...).

Stoichiometry

As to the windshield; I keep it where I can look over it unless it's really wet then it goes to the top (CeeBaily+4+2). I'm surprised I got as good as I did due to all the extra lights I now have hung on the front of it!

Big windshield and extra equipment are/can be counterproductive to fuel mileage.

AVCC, often, whacks throttles WFO when you press the "Zoom" (resume).

Strip and trim-down for more MPG...

 

[joebiodiesel]

There really isn't too much tuning you can do mileage-wise. As long as the O2 sensor is plugged in and working correctly it will keep the mixture at 14.7:1 at steady cruise. That's a great fuel mixture for a compromise of performance and mileage. Your best chance of any gains are the driving habits already mentioned.

If you are an aspiring hyper-miler then disconnect the O2 sensor, buy a gas bench, install a power commander and get to work. You could probably run ratios out to 17:1 or more, but it wouldn't perform well, and with the revs our bikes can make you could certainly do some engine damage.

So, I recommend leaving it stock for good fuel mileage.

Joe

 

[fljab]

As to the windshield; I keep it where I can look over it unless it's really wet then it goes to the top (CeeBaily+4+2). I'm surprised I got as good as I did due to all the extra lights I now have hung on the front of it!

Big windshield and extra equipment are/can be counterproductive to fuel mileage.

AVCC, often, whacks throttles WFO when you press the "Zoom" (resume).

Strip and trim-down for more MPG...

I had the windshield last yr, but the extra lights hanging off the front are new for this yr. I really thought that it would adversely affect MPG, but I've run the best tanks ever since the mod altho I'm not crediting one from the other.

I was honestly surprised that it did so well, so that had me thinking maybe there's more to be had MPG-wise...

My AVCC responds slowly IMO, and in fact in hills it's a pita sometimes. I have a good PVC vac canister I built with a check valve. My dip switches are set to 1-4-7 ON, 2-3-5-6 OFF. Not sure if there is a better way to set it, but I guess that's a separate problem/issue than my post here - need to do some digging on that.

 

[charismaticmegafauna]

...I was honestly surprised that it did so well, so that had me thinking maybe there's more to be had MPG-wise...

Sounds like you're doing the best you can with what you've got...?

Often increases in fuel mileage (given a fixed engine size) are found in the aerodynamics arena: frontal area and coeficient of drag. The laws of physics are difficult to argue with...

Light weight, small engines, and streamlining = fuel economy.

 

[charismaticmegafauna]

I'm just curious...what if you want better economy? Longer tanks while on the interstate? Any thoughts?

This from our own 'Silver Penguin':

My current daily rider...BMW's...G650GS. I've put 15K miles on...Fuel economy has reached 80mpg at times.

I can verify those mileage figures -- I have a friend with a BMW F650GS Dakar -- and, in general/ordinary riding, I've observed him getting 75 MPG. I think BMW/Rotax does this by using very sophisticated computer control of the Fuel Injection: using no-to-very little fuel when the rider's not asking for power and a closed-loop 02 sensor.

It appears to be a different approach to how the F.I. is controlled... :huh:

What you may be looking for might not exist (yet) -- the "Fuel Mileage" Power Commander...?

 

[fljab]

My current daily rider...BMW's...G650GS. I've put 15K miles on...Fuel economy has reached 80mpg at times.

I can verify those mileage figures -- I have a friend with a BMW F650GS Dakar -- and, in general/ordinary riding, I've observed him getting 75 MPG. I think BMW/Rotax does this by using very sophisticated computer control of the Fuel Injection: using no-to-very little fuel when the rider's not asking for power and a closed-loop 02 sensor.

It appears to be a different approach to how the F.I. is controlled... :huh:

What you may be looking for might not exist (yet) -- the "Fuel Mileage" Power Commander...?

You could very well be right! Yes, I know of maybe downsizing to a BMW F series or maybe a 650V strom (?), but just sorta wanted to explore better economy with what I have + I pretty much plan to put 100K+ miles on this bike.

I am no computer/FI expert by any means, but on (some) cars, isn't there an aftermarket control where you can put it in "valet" mode so it only revs to ~2K or so? I'm saying that because it seems there are products out there - not necessarily for FJR's - that allow multiple tunes to be loaded and you can switch between them.

I know on my '05 Dodge Magnum R/T, there is a plug in product you can get that allows 6 different settings for the transmission, from stock to tire-squealing firm, all with a touch of a rotary switch. Not the same thing I know, but still a computer control.

How does the new C14 go into economy mode with the flick of a switch?

 

[charismaticmegafauna]

You could very well be right! Yes, I know of maybe downsizing to a BMW F series...but just sorta wanted to explore better economy with what I have + I pretty much plan to put 100K+ miles on this bike.I am no computer/FI expert by any means...isn't there an aftermarket control...?

I'm saying that because it seems there are products out there - not necessarily for FJR's - that allow multiple tunes to be loaded and you can switch between them.

I'm in no way an expert either...

But, I think the problem lies with the FJR's limited ECM computer power and limited number of adjustable engine controls -- just not as sophisticated as some...?

Too bad about that 100K Mi. plan -- given some knowns: FJR's avg 40 MPG and 'Silver Penguins' 80 MPG -- in 100K miles (at $4/gal) it'll cost you an extra $5,000...

How does the new C14 go into economy mode with the flick of a switch?

I don't know...

But, I suspect more computing power... :blink: