2 post about MPG 2020 Chevy 3.0 diesel MPG WAY DOWN

[wildbill1973z28]

For those who did not read first post. For 16,000 miles this truck averaged over 28 miles per gallon every freaking tank !(Only kept up with by on board computer did not write it down). November 1 check engine light came on, then call came in from onstar! That if the check engine light started flashing truck was going to shut down on the spot.
Light was for number three glow plug plus there was a recall for break reset.
Since all the work was completed at the dealership truck will get 23 miles to the gallon!The dealership has started a TAC. So they can research all the avenues of troubleshooting with this new 3.0 L diesel.10 speed transmission.
1. One of the first things they wanted me to do was fill it up drive 100 miles or so and fill it up again? And do it on paper.
Here is where it gets Interesting
145 miles down 120 -4.8 gallons when filled up! 30.21 MPG
145 miles back up i20-5.9.gallons when filled up! 23.7 MPG
Let’s here it ? What is going on? (I know normally you run the tank to empty)

 

[jdm333]

I'm my opinion, 100 miles is nowhere near enough to get an idea of mileage, especially with a diesel. Diesel fuel foams when filling and, in my experience, very inconsistently.

My motorhome has a 100 gallon tank and I swear I've had 20 gallons of foam after some fill ups.

Did they reflash your computer when in for the original service? If so, they may have corrected an overly optimistic algorithm for calculating mileage. That or they may have removed a cheat similar to what volkswagen got caught using (now where is my tinfoil hat??}

 

[wildbill1973z28]

I'm my opinion, 100 miles is nowhere near enough to get an idea of mileage, especially with a diesel. Diesel fuel foams when filling and, in my experience, very inconsistently.

My motorhome has a 100 gallon tank and I swear I've had 20 gallons of foam after some fill ups.

Did they reflash your computer when in for the original service? If so, they may have corrected an overly optimistic algorithm for calculating mileage. That or they may have removed a cheat similar to what volkswagen got caught using (now where is my tinfoil hat??}

Thanks

 

[lftd&pwrstrok'n]

I'm my opinion, 100 miles is nowhere near enough to get an idea of mileage, especially with a diesel. Diesel fuel foams when filling and, in my experience, very inconsistently

My thoughts precisely, that's why I have never bothered doing the math to figure out my mileage. I know that once the handle clicks off the first time, I can slowly add another 4-5 gallons of fuel. I don't think there is anyway to consistently get the same fill up.

 

[wildbill1973z28]

My thoughts precisely, that's why I have never bothered doing the math to figure out my mileage. I know that once the handle clicks off the first time, I can slowly add another 4-5 gallons of fuel. I don't think there is anyway to consistently get the same fill up.

I agree! This is my first diesel! And was so happy with the 28MPG- but not happy now with the 24.

 

[jeep78]

300 miles, and fill up at the same pump. That will give you more usable numbers than 100 miles between fillups.

 

[UptaCamp]

27 mpg average is pretty close to what it was. Try measuring over longer distance.

 

[dcline9163]

Drove mine to Mississippi last Monday and mine was 25.3 and running between 70 and 80 mph,just by the truck's calculator, I'm good with that too, but I agree with filling a diesel, a lot to take in consideration.

 

[lftd&pwrstrok'n]

I agree! This is my first diesel! And was so happy with the 28MPG- but not happy now with the 24.

Before my computer data system gave out, I was getting between 8-10mpg. Count your blessings w/ 24!!!

 

[wildbill1973z28]

Drove mine to Mississippi last Monday and mine was 25.3 and running between 70 and 80 mph,just by the truck's calculator, I'm good with that too, but I agree with filling a diesel, a lot to take in consideration.

Are u driving the 3.0