Awful gas mileage
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Joined: Oct 2018
Posts: 77
Likes: 22
From: Canada
Without a tuner of some sort, it is pretty much impossible to help your buddy out. He is running short shots with a high flow air cleaner. Does he have the baffles in or out? I have a similar setup and run a PowerVision as my tuner. I have pretty much eliminated my decal popping, and I am getting 185 miles/tank. I have the baffles in with homemade lollipops as well. There may be a tune in the ECU and your buddy just inherited a bad tune, and no tuner to load new maps. If there was no tune loaded and it was stock, it would be very lean and mileage would not be so poor. With EFI bikes you're pretty much humped unless you fork out the coin for a tuner. How do the plugs look?
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,160
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From: San Diego, CA
The fact that it is a sudden drop in MPGs is the key...
Assuming all else is equal, ie: riding style, riding locations, and the bike is well maintained.... the sudden drop in MPG suggests an over fueling issue. Also, backfiring can be caused from over fueling
Has he looked at the plugs?
There are several things that can break/malfunction and cause an over fueling issue. It could be one of the sensors that monitor the airflow that tells the ECM to supply the proper fuel, the fuel injectors, or even the O2 sensors.
Usually it is a sensor that needs to be replaced/cleaned like the MAP sensor, IAC sensor, etc.. or the wiring to a sensor has been pinched, chafed, or broken.
He needs to start investigating the various sensors, their wiring , and then ultimately some hardware like the fuel injectors and/or O2 sensors to find what is causing the over fueling into his bike...
Good luck with the fix
Last edited by hattitude; May 25, 2021 at 08:59 AM.
Grand HDF Member
Joined: Mar 2018
Posts: 3,873
Likes: 3,482
From: Arizona
You'll need a tuner to begin with. I have a Power Vision. I would get one from Fuel Moto. You can leave it plugged in and tune these on the fly. Get a RAM mount.
With a fairly quiet Supertrapp 2 into 1 pipe and S&S 583 cams I get about 160 miles to a tank. I'm a heavy guy and tend to get on the the throttle in Phoenix region.
With those nice looking loud 2 in 2 pipes you're just not going to be running efficiently. Decel pop drives me batty, that would be my first problem to solve.
With a fairly quiet Supertrapp 2 into 1 pipe and S&S 583 cams I get about 160 miles to a tank. I'm a heavy guy and tend to get on the the throttle in Phoenix region.
With those nice looking loud 2 in 2 pipes you're just not going to be running efficiently. Decel pop drives me batty, that would be my first problem to solve.
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Joined: Sep 2011
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From: ontario, canada
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Tourer
Joined: Feb 2016
Posts: 486
Likes: 155
From: British Columbia
Component failure maybe.
Sounds elementary but have you guys checked the speedo for a code being thrown ? Seems if there is an electronic component failure, it should throw a code. Best of luck.
Novice
Joined: Apr 2021
Posts: 20
Likes: 13
From: Sunshine Coast
Something that hasn't been mentioned yet, I would rule out intake leak and exhaust leakage before the O2 sensors (if fitted) Both those things can upset the air/fuel ratio noticeably. It's probably worth mentioning to rule out poor economy caused by lots of little things too, like low tyre pressure, dirty air filter, belt adjustment, temp sensor and all the normal maintenance type stuff. A decent dyno shop will want all that stuff done before tuning it anyway, they do like to pump up the bill if they spend a couple of hours putting new filters and plugs on the bike.
I would expect that short pipes and air cleaner like that would also require a fuelled up map from standard. That would explain some fuel economy loss from standard, however not a drop with out modification.
I'm guessing that short pipes would make it impossible to hear any form of leak at the flange gasket. A good mechanic will check that in a few minutes. Thats where I would start.
I would expect that short pipes and air cleaner like that would also require a fuelled up map from standard. That would explain some fuel economy loss from standard, however not a drop with out modification.
I'm guessing that short pipes would make it impossible to hear any form of leak at the flange gasket. A good mechanic will check that in a few minutes. Thats where I would start.
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