BCM average fuel mileage

[TJay74]

33 minutes ago, Sierra Dan said:

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.

 

There has never been a way to change, alter or modify the way the ECM calculates fuel mileage on any GM vehicle. Sure, you can reset the dash DIC screen but that doesnt alter the fueling calculation that is used to provide the data on the DIC screen. That is hard coded into the ECM systems.

[Sierra Dan]

46 minutes ago, TJay74 said:

 

There has never been a way to change, alter or modify the way the ECM calculates fuel mileage on any GM vehicle. Sure, you can reset the dash DIC screen but that doesnt alter the fueling calculation that is used to provide the data on the DIC screen. That is hard coded into the ECM systems.

My reference above was not aimed at stating the ECM could be modified or altered in reference to mileage.

I was simply stating you could reset Average Economy displayed in the instrument cluster.

I could do this on my 2015 Avalanche.

GM changed the reading to INST ECON on GMT 900

[EpicLT]

My computer has always been at least 2 mpg off. I don’t get it because I have a 12 year old Infiniti that is accturate to under .5 mpg. Seems that in 12 years Chevy could have gotten close to the ability to calculate accurately

[TJay74]

2 hours ago, EpicLT said:

My computer has always been at least 2 mpg off. I don’t get it because I have a 12 year old Infiniti that is accturate to under .5 mpg. Seems that in 12 years Chevy could have gotten close to the ability to calculate accurately

 

The fuel injection system is completely different than years ago, back then we had return lines that ran fuel back into the tank. The current DI dont use a return line, all fuel sent up to the front of the engine is considered as used in the combustion process. So thats why the DIC fuel mileage is an estimate.

The EPA test is done based off of actual fuel mileage, not the computer system estimate.

[baddog2010]

On 2/18/2019 at 7:54 AM, TJay74 said:

 

 

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.

I thought it to be ECM controlled and the BCM handles the display of such info from ECM. It still seems that the ECM calculation is faulty. One would think that a $50,000 vehicle would have the ability to calculate or allow manual manipulation of the ECM calculation to fine tune the actual fuel mileage. As also to display the gear the trans is in somewhere on the DIC, yet another peev of mine. I still believe it is false, inaccurate information misleading people. 1.5-2.5 mpg better than actual mpg ?!? that's openly false misrepresentation. Thought there were laws against that. But if it makes EPA n Gov happy guess that makes it OK.

A certified GM tech at a local dealership said it was a BCM function and to get the MPG display to 'learn' 'my' driving mpg it was necessary to reset the 'best' fuel economy setting with each fuel fill up.....I smiled, said thank you, got in my truck and left....  what do I know... I'm not a certified GM tech.

[SS502]

On 2/17/2019 at 1:09 AM, 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.

So is it all manufactures or did you just feel the need to single out GENERAL MOTORS?

[baddog2010]

I prefer Chevy over all makes. My experience has been with Chevy/GM, '15, '16 Impala, '18 Silverado. All having same ECM mpg inaccuracies. Cant say for other manufacturers, have read some reports of similar results. Seems higher ECM MPG than actual manual results started with the '15 series of many vehicles from what I have read from others. All Vehicles are grossly over priced, yet we have to eat it and suffer the conglomerates that keep jacking up prices to line their pockets and we foolishly keep buying. The reasoning for vehicle prices to increase so much so fast over the last 10-15 years is outrageous. Greed and big oil owners. My first house was only $75k. I think its extremely wrong for any manufacturer to tweek, misrepresent failures and mpg results that are not accurate, only to fool the buyer that their getting something that is false. Many people will simply just get use to it or don't care, saying goes...give 'em two weeks they'll forget about it. 

Apologize if i hit nerve with some folks. But Facts are facts. This is'nt a bash GM statement. I got on a rant about a $50,000 2018 pickup being no better than my $2500 1998 pickup. My '98 gets the same mpg as my '18. Other than looks not sure now why I bought the '18.

So it appears there is no fix or ability to modify the ECM parameters to produce accurate results. Guess "I'll have to get use to it". Or sell it and go electric....HA...

So no more ranting and stick to Q n A's on these wonderfully fine, advanced, improved technology vehicles.