Loosing more and more MPG!!

[BG1988]

I’m not arguing that the timing of lights may have been adjusted, but to say that the reason is so people burn more fuel to drive up gas prices is what I’m called BS on.

In a lot places the pedestrian buttons at traffic lights are pretty much disabled because all lights are synced up with the greater system.

https://www.google.com/amp/s/www.bl...pedestrian-push-to-walk-buttons-actually-work

that is fake and might only apply to tiny streets in Portland, Oregon
its not automatic, not all of them here in the city of LA
in my neck of the woods you have to press it other wise you will have a short light and a DONT WALK (just enough to get a few cars ) the street speed limit is mostly 45, 50 to 60mph so you don't want to mess with a short light... most main roads are 4-6 lanes(total) wide... do you think caltrans is going to cycle a walk for an invisible person ??

if it does have automatic it might be in school hours at some lights(near a school) and those have 20 second extended crossing time...



they also use camera detection controlled intersections... I have been testing my turn signal maybe 1/4 mile back or so to see if activate the left turn it has done it a few times not always though( independent sensor controlled left turn lights)..

I gotta to do more experimenting on that

the only one time the button failed me was at night in ventura,ca when i was 17 the light was cycling for me green. then yellow red (for the other person) in that split second a car zoomed right by me. going about 100mph i though he was going to stop. but the light recycled back to green for him.. almost was splatter on someones windshield.. maybe someone was watching the camera at that intersection and override the signal

 

[BG1988]

I’m not arguing that the timing of lights may have been adjusted, but to say that the reason is so people burn more fuel to drive up gas prices is what I’m called BS on.

In a lot places the pedestrian buttons at traffic lights are pretty much disabled because all lights are synced up with the greater system.

https://www.google.com/amp/s/www.bl...pedestrian-push-to-walk-buttons-actually-work

it was a joke remember the state/city is down on fuel tax revenue this year adjusting the lights and claiming it's to slow down drivers


these cities want to make money GAS is like almost a dollar in just sales tax..


by even claiming it's to slow down drivers is kinda suspicious in itself

i see people still blowing threw red lights all the time still so it changes Nothing

I say let them die in a crash... that is why I got a SUV instead of another Car

(more room to crush)


1990s honda accord vs 1990s tahoe your honda gets crushed into a cube


do you think the people in the tahoe walked away or the people in the accord

the accord was hit at 55MPH and got thrown 100 feet or so (they were making a utrun)
Answer: people in the accord left in a body bag..

 

[swathdiver]

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

Brandon, do you have one of those Bluetooth OBDII adapters and the Torque Pro app or Dash Command for your phone? If not, get it and set it up to read your Long Term Fuel Trims and Alcohol Content. Also set it up to look at all 4 of your oxygen sensors.

I suspect that your cats are slowly failing, this is what happened to mine a few years back. More recently, one piston on a front caliper was causing the pads to drag on the rotor and got progressively worse, cause the steering wheel to wobble and then a few months later it locked up and smoked the brakes on that side. Anyway, pull the wheels and check that out too.

With the O2 sensors, you are looking to see that your upstream sensors are moving continually while cruising and that the downstream sensors are fairly steady. If they are moving like the upstream sensors, the cat(s) are no good.

The LTFTs can identify all sorts of problems, if high while parked at idle, that's usually a sign of a vacuum leak (like intake gaskets). But don't freak out when they're -25 right after refueling, the computer is figuring out the alcohol content and adjusting for it. The computer needs at LEAST seven miles or so calculate a new alcohol content after refueling, it is not good to fill up right down from the house and then go home all the time. We often fill ours up about 20 miles from home and it begins to settle down at the end of the highway run but still usually fine tunes itself the next day, or two or three!

Your truck was originally rated for 14 City and 20 Highway. Knock off a couple MPGs for the lift and tires. The average economy of these trucks across all models and years (5.3 engine) of the GMT900 is 14.3 MPG according to research done on Fuelly. My truck's average is 14.8 MPG on 93 octane gasoline (E10).

Any stations with Ethanol nearby? I mix E15 or E10 with E85 and average 15.6 MPG while getting the benefits of high octane fuel at 87 prices.

 

[Jolly Roger]

33's and a lift would drop your MPG prob 1 or 2.. The light bar, prob only at
hwy speeds maybe a hair...
You might want to clean the MAF and the Throttle Body...
I would suspect that your upstream Oxygen Sensors may be off, esp
if you've been running really rich... O2 sensors are kind of a tune up item..
I don't see the evap code causing any MPG issues, although very annoying..

I wonder if the shop that jacked up the O2 sensor wiring got into the vehicle
side of the O2 and "repaired it"... You can't extend or really repair O2 wiring as
it screws up the relationship of the voltage... Check to see if that's the case..
If so, find used wiring harness for the O2's or see if gm still makes it

Thank you Foggy, I have a brand new ACDelco MAF I just installed after I herd about the other ones being problematic. The TB is clean as a whistle and I even threw on a new MAP for good measure. I asked the mechanic to check out/inspect the O2 wiring and he said he did...I also think he was more inclined to wanting to prove me wrong and himself right about the trim levels. Before I had the latest work done I happen to see this (pic) right under the pas. side door. thus why I asked for them to inspect the wires..

Whats the weight difference in the current tire/wheel combo vs. what was on it? When I put some 20s with 305s on my Dmax in place of the factory 17s with 265 I lost fuel mileage. The 20 are heavier..

Surprisingly there was little weight difference. I was expecting more for sure. The ones that were on it were 265/70/17 E ....and I replaced those with a BFG 285/70/17 E
Think it only increased the size by an inch overall in ht. I wasnt expecting to find load range "E"s on it,...I thought they were "Cs" all along.

10-12 MPG city is normal for the 5.3L engine most areas have adjusted the traffic lights so you burn more
fuel

the worst i have ever gotten in my 3.8l was 12MPG in the metro area years ago so yeah your tahoe is sipping fuel.. even the 4.8l sips fuel more efficiently

It's a Conspiracy to boost up the oil/gas prices


Now on to the CEL
P0446 is a restriction in vent "solenoid" this is a electronic code not a cat code(if it was the cat you would have a P0420/P0430 code)


so you have an issue with one of the following:
Baro(MAP sensor)
MAF sensor
IAT sensor
ECT sensor
Ambient air?
TPS_FA (Throttle Position Sensor)
Vehicle speed sensor
engine power limited
View attachment 252127

Thank you BG.
If 10-12 MPG is normal for the 5.3s than you made my day. (really) not even being sarcastic!, all I could find were higher numbers.
The vent solenoid has been replaced about 4 times now. The MAP, MAF are new. I think Ill be checking out the TPS next. Before I had this shop work on it, and they reset the Fuel trim..my gas pedal seems to be less responsive by just a bit. It seems like before if I gave the pedal a tap while idling the RPM needle was faster to rise than what it is now. Now it seems to just kinda creep up and fall just as slow... Maybe my imagination? but I remember that was the first thing I noticed when I got it back from service. I was thinking the computer may need to relearn?...

Brandon, do you have one of those Bluetooth OBDII adapters and the Torque Pro app or Dash Command for your phone? If not, get it and set it up to read your Long Term Fuel Trims and Alcohol Content. Also set it up to look at all 4 of your oxygen sensors.

I suspect that your cats are slowly failing, this is what happened to mine a few years back. More recently, one piston on a front caliper was causing the pads to drag on the rotor and got progressively worse, cause the steering wheel to wobble and then a few months later it locked up and smoked the brakes on that side. Anyway, pull the wheels and check that out too.

With the O2 sensors, you are looking to see that your upstream sensors are moving continually while cruising and that the downstream sensors are fairly steady. If they are moving like the upstream sensors, the cat(s) are no good.

The LTFTs can identify all sorts of problems, if high while parked at idle, that's usually a sign of a vacuum leak (like intake gaskets). But don't freak out when they're -25 right after refueling, the computer is figuring out the alcohol content and adjusting for it. The computer needs at LEAST seven miles or so calculate a new alcohol content after refueling, it is not good to fill up right down from the house and then go home all the time. We often fill ours up about 20 miles from home and it begins to settle down at the end of the highway run but still usually fine tunes itself the next day, or two or three!

Your truck was originally rated for 14 City and 20 Highway. Knock off a couple MPGs for the lift and tires. The average economy of these trucks across all models and years (5.3 engine) of the GMT900 is 14.3 MPG according to research done on Fuelly. My truck's average is 14.8 MPG on 93 octane gasoline (E10).

Any stations with Ethanol nearby? I mix E15 or E10 with E85 and average 15.6 MPG while getting the benefits of high octane fuel at 87 prices.

Do you have a suggestion as to what OBDII Bluetooth to get? I remember your posts and warnings about the brakes and the little spring, The truck seems to coast like a dream and the guys doing the breaks used ample lube on all the friction areas. (I can see it)
I've talked about the cats here before and with only 73k on the truck... do you think its likely? It does smell like Im roasting coffee if I really get on it.....its either coffee smell or something similar to two part epoxy curing.....

With the reset of the alcohol content after a fill up, Im under the impression that the system closes the loop temporarily by closing the purge solenoid. It crossed my mind, (and if I understand the system correctly) that if Im getting a PO446 maybe I need to check and see if Im getting power to the purge solenoid? I mean,..dang thing has been changed 4 times now trying to fix the fill-up issue and code. Maybe there is a problem with the power going to it?

7 miles! I've been looking for that little bit of information for a long time now too! I even asked the mechanics and non of them knew!
I never make it more than a 1/4 mile until I get home and shut off the engine after a refill. You always full of good info swathdiver!

Are there any particular problem areas on the 5.3s that I should check extra close for vacuum leaks? The elbow going into the brake booster turns pretty freely and I've been meaning to change it...
Im off the Amazon to shop for OB2II Bluetooth gizmos...
Thank you!

 

[Jolly Roger]

Brandon, do you have one of those Bluetooth OBDII adapters and the Torque Pro app or Dash Command for your phone? If not, get it and set it up to read your Long Term Fuel Trims and Alcohol Content. Also set it up to look at all 4 of your oxygen sensors.

I have that Superchips flashpaq,..it may be able to do some of what you ask. I think I just need to download the software. Ill check.

 

[swathdiver]

Do you have a suggestion as to what OBDII Bluetooth to get? I remember your posts and warnings about the brakes and the little spring, The truck seems to coast like a dream and the guys doing the breaks used ample lube on all the friction areas. (I can see it)
I've talked about the cats here before and with only 73k on the truck... do you think its likely? It does smell like Im roasting coffee if I really get on it.....its either coffee smell or something similar to two part epoxy curing.....

With the reset of the alcohol content after a fill up, Im under the impression that the system closes the loop temporarily by closing the purge solenoid. It crossed my mind, (and if I understand the system correctly) that if Im getting a PO446 maybe I need to check and see if Im getting power to the purge solenoid? I mean,..dang thing has been changed 4 times now trying to fix the fill-up issue and code. Maybe there is a problem with the power going to it?

7 miles! I've been looking for that little bit of information for a long time now too! I even asked the mechanics and non of them knew!
I never make it more than a 1/4 mile until I get home and shut off the engine after a refill. You always full of good info swathdiver!

Are there any particular problem areas on the 5.3s that I should check extra close for vacuum leaks? The elbow going into the brake booster turns pretty freely and I've been meaning to change it...
Im off the Amazon to shop for OB2II Bluetooth gizmos...
Thank you!

As for the OBDII adapters, we bought a Foseal WIFI so my kids can use it on their apple phones. Works with my android too.

Yes, the cats can fail prematurely if they get contaminated. Let's say an injector stuck open or excess oil was spit out, those things can foul or kill a cat.

P0446 usually means that there is a blockage in your lines causing too much vacuum to be developed. Probably charcoal in the line between the canister and the engine.

You really need a Tech-2 to diagnose that PITA properly.

All LS engines usually develop vacuum leaks along the intake gaskets at some point. While running a graph of the upstream O2 sensors, you can spray water or sprite or propane along suspect areas such as that booster and see if the O2 Sensor reading spike or change.

Your short trips back home eventually knocked the system out of calibration. Try altering your routine so you drive for 7 miles or so before stopping, or get the Tech-2 and reset it once it gets out of whack!

 

[Jolly Roger]

I was looking at this one, but Ill buy the Foseal if you have had good luck with it!
https://www.amazon.com/BAFX-Product...85HJTSYK4C4&psc=1&refRID=PX7NB75BA85HJTSYK4C4
I have android

 

[exp500]

BAFX is a good unit, Can Buy direct drom them too.

 

[swathdiver]

I was looking at this one, but Ill buy the Foseal if you have had good luck with it!
https://www.amazon.com/BAFX-Product...85HJTSYK4C4&psc=1&refRID=PX7NB75BA85HJTSYK4C4
I have android

Looks better actually and look at those reviews!

If memory serves, we chose the Fosseal because it was listed by the app designers as being compatible with their products. Even if that one is not, it will probably work just fine.

 

[Jolly Roger]

Ordered...................with a fancy extension cable