Getting 8.5 mpg need help

[BlueCollarTahoe]

Ok, let's go back to the tires. Are they P-Metrics or LT tires on their now? If LT and you're running the air pressure the same as door sticker you're under-inflated (unless your door sticker is for an LT tire, not a P-Metric).

Did you run those little bottles of Super-Tech yet?

If all else is well I'd start eyeballing those cats. Changed mine and my mileage is finally back up to near where it was when I bought it and getting better. Haven't been driving it lately due to back pain though so no updates on its mpg journey.

AT terrains and the pressure was around 42 i think when i checked it. i ran BGK44 and that Berrymans stuff. how do i check the cats? the temp of the pipes before and after the cat after driving?

 

[swathdiver]

42 psi is a little low but should not be the mpg culprit. 42 psi will support 4,300 pounds an axle (assuming 265-70-17 tire). Your maximum axle weight is probably just under this.

How did the fuel system cleaners work out? As for the cats, that seems like a good way to do it. Maybe someone else will have better ways?

How have the LTFTs been? Last time the right bank was a little off.

 

[Scottydoggs]

im still getting 9 mpg all local stop and go BS driving. im tuned with a wideband. so im fairly certain all my junk is up to *****.

so being a city driver, it just might be normal.

if i get on the hwy for along trip and reset the mpg avg ill hit 20's. but once im back to local its falls back to that 9-10 mpg no matter how much i baby it and feather the gas pedal.

if the cats were really on the way out the truck would have a pretty noticeable power loss, show misfires and even flash the cel when wot.

temp laser can show the cats temp, pre and post cat. when really clogged up you can drive it somewhat hard at night, then look under the truck to see if the cats or pipes are glowing red. if glowing, they are clogged up for sure, but by that time you already feel the power loss. kinda like the old bananas in the tail pipe bit from Beverly hills cop.

 

[swathdiver]

if the cats were really on the way out the truck would have a pretty noticeable power loss, show misfires and even flash the cel when wot.

Mine didn't.

But you're right about the stop and go city driving. Some days I don't even get up to 45 mph and stop at every darn light from home to my destination. And such trips for me like that are often under 10 miles. Even knocks the Montana down to the 16s.

 

[Scottydoggs]

my drive to work is like maybe 5 miles. im right on the hwy for about a mile or so, so i get up to 70 mph and take the next exit lol, then stop and go. stop sign every 500 feet. then the way home is all local roads with a hill on a 45º angle.

looking up it. i know this hill is killing my mpg.

https://www.google.com/maps/@40.877...4!1sQ-bMkZXkEhdwZDozWTm3cA!2e0!7i13312!8i6656

looking down the hill. i went up this after a 6 inch snow storm un plowed. you dont want to go down it even after its been plowed. and you really dont want to fail on the way up either. as tom pettys says, coming down is the hardest part lol

https://www.google.com/maps/@40.878...4!1sHreeqKcg0R0NvMJLYvGT2g!2e0!7i13312!8i6656

 

[BlueCollarTahoe]

42 psi is a little low but should not be the mpg culprit. 42 psi will support 4,300 pounds an axle (assuming 265-70-17 tire). Your maximum axle weight is probably just under this.

How did the fuel system cleaners work out? As for the cats, that seems like a good way to do it. Maybe someone else will have better ways?

How have the LTFTs been? Last time the right bank was a little off.

i didnt see any difference in the mpg after the cleaners. the rb was off at idle? how should i check them or track them? idle, driving at different speeds etc??

im still getting 9 mpg all local stop and go BS driving. im tuned with a wideband. so im fairly certain all my junk is up to *****.

so being a city driver, it just might be normal.

if i get on the hwy for along trip and reset the mpg avg ill hit 20's. but once im back to local its falls back to that 9-10 mpg no matter how much i baby it and feather the gas pedal.

if the cats were really on the way out the truck would have a pretty noticeable power loss, show misfires and even flash the cel when wot.

temp laser can show the cats temp, pre and post cat. when really clogged up you can drive it somewhat hard at night, then look under the truck to see if the cats or pipes are glowing red. if glowing, they are clogged up for sure, but by that time you already feel the power loss. kinda like the old bananas in the tail pipe bit from Beverly hills cop.

no power loss ive heard that from others who had cats go out. i have the AT, a big 50lb push bar and a 25 lb speaker on the front end so may be the difference down to 8.5

Mine didn't.

But you're right about the stop and go city driving. Some days I don't even get up to 45 mph and stop at every darn light from home to my destination. And such trips for me like that are often under 10 miles. Even knocks the Montana down to the 16s.

yea on the highway mine is good its the stop and go when it goes down.

 

[swathdiver]

Compared to your left bank of cylinders, the right was further away from ideal. Just take another reading like you did last time.

I had no perceptible power loss, no flashing CELs, no misfires, etc. when my cats started throwing codes. When we took off the right one, we could see it was falling apart. My mileage has been steadily improving since.

 

[Idaho45guy]

When I bought my Yukon, the average MPG was at 7.6.

It was test driven only around town, apparently. And hard... After driving it a few hundred miles around town, to work and back, and on a trip to the woods, it is showing 17.7 mpg..

 

[bottomline2000]

Compared to your left bank of cylinders, the right was further away from ideal. Just take another reading like you did last time.

I had no perceptible power loss, no flashing CELs, no misfires, etc. when my cats started throwing codes. When we took off the right one, we could see it was falling apart. My mileage has been steadily improving since.

I switched from Shell to ExxonMobil for my last 2 fillups after what u said about them. Go figure my fuel mileage has crept up another 2mpg. I swear that Shell crap is a lower octane even though they show it as 93 and I only run 93. The truck don't even sound the same and feels like its makimg more power which leads me to believe what u said about shell.

My truck is tuned with a cam and all but before the switch I could barely hear the lope of the cam until after longer drives. Now I hear it after getting to the first stoplight..definitely not a placebo effect..

I'm currently seeing 12.5city with a 3k stall with 4l80 and 3.42 gears. Its probably the worse combo for city driving so there has got to be something up with the OPs truck. my hwy mileage is around 18-19mpg cruising 80mph which may be even better after switching fuels.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[swathdiver]

I switched from Shell to ExxonMobil for my last 2 fillups after what u said about them. Go figure my fuel mileage has crept up another 2mpg. I swear that Shell crap is a lower octane even though they show it as 93 and I only run 93. The truck don't even sound the same and feels like its makimg more power which leads me to believe what u said about shell.

My truck is tuned with a cam and all but before the switch I could barely hear the lope of the cam until after longer drives. Now I hear it after getting to the first stoplight..definitely not a placebo effect..

That made my day, thanks for sharing!