Loosing more and more MPG!!

Jolly Roger said:

This also raises a question with my new Bluetooth OBDII adapter tool that I have coming.
I run the Superchips tool and turn off my AFM. I unplug the Superchips and store it away until its time for someone to service the truck.

Am I going to be able to plug in and run the new Bluetooth OBDII tool while I have the Superchips changes installed at the same time?
..or should I uninstall all the options I have with the Superchips before plugging in and running the new Bluetooth OBDII tool?

The only things I change with the Superchips is turning off AFM, turning off speed limiter, and change tire size so the speedometer is correct.

https://superchips.com/shop/gm-flashcal-for-truck

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What is the timing of you getting 16 mpg and putting in the Superchips tool?

wjburken said:

What is the timing of you getting 16 mpg and putting in the Superchips tool?

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If I understand you correctly you are looking for a correlation to lost fuel due to my usage of the Superchips flashcal?

My loss of fuel or MPG happened right after the front dif and transfer case were changed. A year later I purchased the Superchips tool to delete the AFM. I didn't notice any MPG decrease after installing the Superchips tool and deleting AFM.

Jolly Roger said:

This also raises a question with my new Bluetooth OBDII adapter tool that I have coming.
I run the Superchips tool and turn off my AFM. I unplug the Superchips and store it away until its time for someone to service the truck.

Am I going to be able to plug in and run the new Bluetooth OBDII tool while I have the Superchips changes installed at the same time?
..or should I uninstall all the options I have with the Superchips before plugging in and running the new Bluetooth OBDII tool?

The only things I change with the Superchips is turning off AFM, turning off speed limiter, and change tire size so the speedometer is correct.

https://superchips.com/shop/gm-flashcal-for-truck

Click to expand...

Yes, you can still use the Bluetooth adapter.

I have a DiabloSport intune i3 device that allows me to make some changes like your Superchips does (disable AFM, tire sizes, remove trans torque management, etc) and after it has flashed the ecu and is unplugged, I can use the Bluetooth adapter and Torque Pro app to get all my sensor readings

Sent from my SM-G930V using Tapatalk

gooffeyguy said:

Yes, you can still use the Bluetooth adapter.

I have a DiabloSport intune i3 device that allows me to make some changes like your Superchips does (disable AFM, tire sizes, remove trans torque management, etc) and after it has flashed the ecu and is unplugged, I can use the Bluetooth adapter and Torque Pro app to get all my sensor readings

Sent from my SM-G930V using Tapatalk

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Thank you!

Jolly Roger said:

My MPG just seems to keep going down no matter what I try.

2007 Tahoe 5.3 Flex Fuel
4x4


Anything come to mind after hearing my long winded story?

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Jolly Roger - I don't know what AFM is, and I have NO IDEA how any engine built after 1996 works but it strikes me you should find a competent mechanic who excels at diagnosis, have a compression test, and basically fix what the codes are implicating. Strikes me an exhaust analysis might shed light too.

However, in principal if you were getting 16mpg had no problems and no codes, then put a lift and 33" tires on it, I would expect at least a 10-12% drop in gas mileage no matter where you started from. That would be within each type of driving or driving range, so the mileage drop in actual gallons would vary depending on your speed. It sounds like you already knew this(?), but are lamenting that it's been made worse by the problems that preceded your tire size change.

Incidentally, .... and I'm not trying to be a dick or killjoy here, but with an IFS SUV like these, a lift and big tires has limited benefit off-road. It lifts the body out of harms way but does nothing for articulation. At the end of the day we still have IFS in front.

Don't get me wrong! Getting that undercarriage up and away from the rocks is worth something. You don't have to be as careful or slow. However if you going to do a lift and you're serious about trails a solid front axle conversion might be worth the effort and I think doing that conversion actually necessitates a lift.

Easiest ways to kill mileage are underinflated tires, altering aerodynamics (even by lifting), increase in tire/wheel or drive-line weight, oversized hi-output alternators.

RBlack - 90 Blazer[retired], 96Tahoe [retired], 2020 Tahoe

Jolly Roger said:

Thought I had the 3:73 for the longest time until I started decoding my RPO's
Is the 4:10 harder to come by?

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go get a g80 3.08 if you want better mileage... 4.10 is for towing

retiredsparky said:

Brandon, I didn't see in this thread anybody talking about AFM delete.

It is a great mod, since it eliminates an expensive repair down the road.

But, there is a cost in fuel economy, which can be 1-2 mpg, depending on city/hwy driving percentage. That AFM system will constantly switch between 8 and 4 cylinders. The newest version controls even more cylinders (A GM solution to a crappy solution-make it worse).

I would rather pay for fuel than repairing the engine.

Also, in the future, you could experience a failure in the sensor that detects level of alcohol in the fuel. It is not an uncommon failure.

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the issue with AFM is a factory error a shit load of them left the factory.. with loose bolts (the VLOM valley cover) this causes excessive wear and tear (push rod and lifters) to the engine.. basically if you did not catch it early you're screwed... also you're at a significant risk of starting a fire ( if you park inside your house) there has been a couple of fires all ready it's rare but does happen ..

BG1988 said:

go get a g80 3.08 if you want better mileage... 4.10 is for towing

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I think the "G80" designates a Positraction or Limited Slip, and a "G91" for a 3.08 rear gear. My RPO says "GT5" which should be the 4:10 gear if I decoded it all right. I also have a "G80" listed on my RPOs...

G80 is an actual auto-locker - I believe it only works below 35mph, 3.08s are GU4 - you can have a G80 with any gear set.

GreyStone said:

G80 is an actual auto-locker - I believe it only works below 35mph, 3.08s are GU4 - you can have a G80 with any gear set.

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So....is there a chance they replaced my front differential with the wrong gear? Is that even possible?

Remember the notice of MPG loss was after the transfer case and front differential change....
and I think the front drive-line is always engaged on these..hhmmm