Fuel Range Question
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Joined: Sep 2019
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From: Blacksburg SC
Fuel Range Question
I've got a fuel economy question (yes, I know...it's a bike, who cares?). My 15 Street Glide Special has gotten strange on range and economy--I only noticed due to riding to/from work. On a 75-80 degree day, normal highway riding at 70-75 mph it gets about 44 mpg(per gps). 70-75 degree night, running same speed it's getting 38 mpg on average(per gps). Always start and let it warm up, stock bike other than SVT Boneshakers slip-on exhaust(been on there for about 5-6 years). Fresh 3 hole service, new plugs and air filter at 35k, currently sitting at 37.5k. Not so much bothered by the mileage as much as wondering if there's something wrong with the bike that I'm missing. Display typically shows range being about 225 at fill-up, used to run 250-260. Just curious what the great minds here think or have seen. Sorry if this is posted in wrong place, wasn't sure where to post.
Last edited by James-4speed; Apr 3, 2024 at 11:21 PM.
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sooooooooo many factors
the only way to hone in is to do data logging, looking at short term and long term fuel corrections. the long term will be more insightful, the short term gives an idea of how well the system is working at present point.
an engine responds diff to a lot of things like temp and humidity and such.
for starters, look at O2 sensor data and at dwell times, a lazy sensor will increase fuel usage. next i would look at the map sensor. most newer systems have the map ported into the manifold but if yours is connected via hose, look for leaks.
also do not forget fuel quality and road conditions.
also of note is that GPS is relative just like radar.
the only way to hone in is to do data logging, looking at short term and long term fuel corrections. the long term will be more insightful, the short term gives an idea of how well the system is working at present point.
an engine responds diff to a lot of things like temp and humidity and such.
for starters, look at O2 sensor data and at dwell times, a lazy sensor will increase fuel usage. next i would look at the map sensor. most newer systems have the map ported into the manifold but if yours is connected via hose, look for leaks.
also do not forget fuel quality and road conditions.
also of note is that GPS is relative just like radar.
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Joined: Sep 2019
Posts: 79
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From: Blacksburg SC
That is a valid point that had completely slipped my mind. Just took over doing maintenace myself on the bike (had dealer servicing since I had an ESP--less headache if something happened) and it hadn't occurred to me to go there. I know they have one, and I know the service interval is some insane mileage for a fuel filter, IMO. Thanks!
Thread Starter
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Joined: Sep 2019
Posts: 79
Likes: 13
From: Blacksburg SC
sooooooooo many factors
the only way to hone in is to do data logging, looking at short term and long term fuel corrections. the long term will be more insightful, the short term gives an idea of how well the system is working at present point.
an engine responds diff to a lot of things like temp and humidity and such.
for starters, look at O2 sensor data and at dwell times, a lazy sensor will increase fuel usage. next i would look at the map sensor. most newer systems have the map ported into the manifold but if yours is connected via hose, look for leaks.
also do not forget fuel quality and road conditions.
also of note is that GPS is relative just like radar.
the only way to hone in is to do data logging, looking at short term and long term fuel corrections. the long term will be more insightful, the short term gives an idea of how well the system is working at present point.
an engine responds diff to a lot of things like temp and humidity and such.
for starters, look at O2 sensor data and at dwell times, a lazy sensor will increase fuel usage. next i would look at the map sensor. most newer systems have the map ported into the manifold but if yours is connected via hose, look for leaks.
also do not forget fuel quality and road conditions.
also of note is that GPS is relative just like radar.
Thanks!
Thread Starter
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Joined: Sep 2019
Posts: 79
Likes: 13
From: Blacksburg SC
Thanks!
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From: Running with the gators
I run top tier. Hoping of course they added some detergents like they are supposed to. I also each oil change add fuel system cleaner like Lucas or what have you.
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Thread Starter
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Joined: Sep 2019
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Likes: 13
From: Blacksburg SC
Thanks!
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Joined: Mar 2021
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From: backwoods
On the riding conditions that give poor economy, gas up and do the math, and make sure it is not something to do with the internal calculator. After awhile I don't trust them. Though odd it is night and day based. Maybe something you are missing, on how you ride night and day. Maybe collect more data to be sure.
Also I am up on how the MAP sensor works, could it be giving different values at night and day, skewing the calculator? Again, I have not idea about the MAP.
Myself, I would collect more data, filling up the tank, and doing the math myself, before I got to worried.
Also I am up on how the MAP sensor works, could it be giving different values at night and day, skewing the calculator? Again, I have not idea about the MAP.
Myself, I would collect more data, filling up the tank, and doing the math myself, before I got to worried.