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BCM average fuel mileage

baddog2010

By baddog2010
in Troubleshooting & Recalls

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baddog2010 Enthusiast

baddog2010

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Is there a way to 'recalibrate' the Average Fuel setting on 2018 Silverado ?
I am aware of the 'reset/clear' option on the dash display for the 'Instant Best mpg display'. Resetting has no effect. When I calculate fuel mileage manually its always 1.5 - 2.5 mpg less than the BCM display. Its been like this since day 1. Had 7 miles when purchased. Current mileage 35??. Assume should be past break in learn period time. I do same fill to neck each time, I dont round gallons. BCM claims 15.5-18 mpg avg, I get 15-16.5 manual. Same 25-30 mile drive daily. Did a 380 mile, 70-80 mph run and vehicle stated 20.1 mpg, manual 17.8. Have not done another long mile run.

SS502 Senior Enthusiast

SS502

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Posted
33 minutes ago, baddog2010 said:

Is there a way to 'recalibrate' the Average Fuel setting on 2018 Silverado ?
I am aware of the 'reset/clear' option on the dash display for the 'Instant Best mpg display'. Resetting has no effect. When I calculate fuel mileage manually its always 1.5 - 2.5 mpg less than the BCM display. Its been like this since day 1. Had 7 miles when purchased. Current mileage 35??. Assume should be past break in learn period time. I do same fill to neck each time, I dont round gallons. BCM claims 15.5-18 mpg avg, I get 15-16.5 manual. Same 25-30 mile drive daily. Did a 380 mile, 70-80 mph run and vehicle stated 20.1 mpg, manual 17.8. Have not done another long mile run.

I honestly don’t know but I don’t think so...I never use that view, I do what you’re doing and go the manual math way...I have my Yaw, Pitch and drive status showing full time.

6A568E94-B534-4701-87DD-B66EEE0ABF5D.jpeg

baddog2010 Enthusiast

baddog2010

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Factory tires 265x75?x18, Somebody mentioned speedo is off, I have a Diablo tuner thought might try jacking with tire size, yet speedo appears proper, relative to other drivers. Dont have a speed, radar check around here, other than those I dont want to be checked by. have to do mile minute check on highway

Darmichar Enthusiast

Darmichar

Posted
Posted
On 2/15/2019 at 8:15 PM, baddog2010 said:

Factory tires 265x75?x18, Somebody mentioned speedo is off, I have a Diablo tuner thought might try jacking with tire size, yet speedo appears proper, relative to other drivers. Dont have a speed, radar check around here, other than those I dont want to be checked by. have to do mile minute check on highway

Get a GPS speedometer app for your phone.

SS502 Senior Enthusiast

SS502

Posted
Posted
3 minutes ago, Darmichar said:

Get a GPS speedometer app for your phone.

Best answer given :thumbs:

Darmichar Enthusiast

Darmichar

Posted
Posted
4 minutes ago, Darmichar said:

Get a GPS speedometer app for your phone.

That said, my 2014 with 3.08 gears was about .5 MPG off all the time when I calculated manually.  My 2018 with 3.23 gears is ALWAYS 1.5-2 MPG off when calculated manually.  I have used a GPS app to check my speed and it is spot on.

baddog2010 Enthusiast

baddog2010

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3 hours ago, Darmichar said:

That said, my 2014 with 3.08 gears was about .5 MPG off all the time when I calculated manually.  My 2018 with 3.23 gears is ALWAYS 1.5-2 MPG off when calculated manually.  I have used a GPS app to check my speed and it is spot on.

GPS vs Vehicle are same..... any other ideas why manual MPG is off ?

Sounds like the VolksVagon scam?!?

Darmichar Enthusiast

Darmichar

Posted
Posted
1 minute ago, baddog2010 said:

GPS vs Vehicle are same..... any other ideas why manual MPG is off ?

I truly don't know.  I drove over the road for 13+ years in Semi's that could track MPG to the +/- .1.  It baffles me why these trucks are so horrible at doing the same.

I've seen others post here in other threads that there is a baseline map that isn't compensated for the different gear-sets they install in these trucks.  Based on what I've seen owning two of them, I believe there has to be some truth to that.

baddog2010 Enthusiast

baddog2010

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I had a '16 Impala that was always off 1.5-2 MPG manual check vs BCM. Figuered it was just a fluke, but now same on my '18 Silverado and hearing lots of other people have same issue.

baddog2010 Enthusiast

baddog2010

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Found some information.

https://www.edmunds.com/fuel-economy/your-fuel-economy-gauge-is-fibbing.html

Seems to be a common issue among all manufacturers. Vehicle fuel economy gauge MPG reports a higher MPG  than actual manual MPG calculations. Tweek the EPA requirements and to make the owners think their getting higher MPG than they really are. Gov Motors, Typical.

6_2LTZ Enthusiast

6_2LTZ

Posted
Posted
7 hours ago, baddog2010 said:

Found some information.

https://www.edmunds.com/fuel-economy/your-fuel-economy-gauge-is-fibbing.html

Seems to be a common issue among all manufacturers. Vehicle fuel economy gauge MPG reports a higher MPG  than actual manual MPG calculations. Tweek the EPA requirements and to make the owners think their getting higher MPG than they really are. Gov Motors, Typical.

My 14 was bang on. Seems like 18's especially are off. 

TJay74 Senior Enthusiast

TJay74

Posted
Posted
On 2/16/2019 at 11:38 PM, baddog2010 said:

GPS vs Vehicle are same..... any other ideas why manual MPG is off ?

Sounds like the VolksVagon scam?!?

 

 

There is no scam, the fuel mileage isnt even calculated by the BCM it is handled by the ECM and is a byproduct of the ECM calculating fuel used by the injector data of how much fuel it believes it has injected. It is only there as a tool and has never been accurate on any vehicle I have ever owned that provided that info. If you want accurate fuel mileage then you need to hand calculate it.

Sierra Dan Senior Enthusiast

Sierra Dan

Posted
Posted

On previous Gen. GM Trucks and SUV's you could reset this.

I have not seen a way to reset on K2's or 2015 up GM suv's either.

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