sudden loss of gas mileage...WTF? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: sudden loss of gas mileage...WTF?


gordinho80
11-28-2006, 02:49 PM
Before i picked up my Wester's Tune, i was getting 250 miles per tank on 87 octane...since the tune, i've been getting 270ish with 89 octane...

all of a sudden, i'm getting less, 240ish now with 89...WTF???

driving style hasnt changed...the only variable i see being an issue is the temp outside and/or the fact that its been 5k miles since my last oil change...

:confused::confused::confused::confused::confused: :confused:

RozmerJJ
11-28-2006, 02:52 PM
All the oil companies are now starting to put out the winter blend of gas. This will cause your mileage to drop and remember that on cold days you will usually allow your car to warm up longer than normal and this to will cause a drop in mileage.

Nukedog
11-28-2006, 02:55 PM
gordonho80 - Octane will not usually affect you MPG...

Different brands may a little bit but should be very similar.

Winter gas burns less effectively than summer gas.

Get some Techron in your system as clogged injectors kill gas mileage...

gordinho80
11-28-2006, 03:40 PM
yeah but such a big difference? wow...i'll get some techron to clean out the injectors...i just cleaned the K&N cone...also need to do that oil change...

MTPockets
11-28-2006, 03:46 PM
going from ~270 to ~240 miles per tank is probably attributed to the ambient temp swings. Ethanol blended / winter gasoline can do it or maybe a pressure drop in your tires.

Joel

Rob
11-28-2006, 04:18 PM
What exactly is "per tank"? 17 gallons? 18 gallons? Running it dry each time? I doubt it. The only accurate way is to track the actual miles driven between fillups divided by the number of gallons you put in the tank. You can't go by a couple of tankfulls either. My average over 3000 miles before the Wester's tune was 16.18 mpg. My average for more than 10,000 after the tune is 16.82 mpg, or around 311 miles on an 18.5 gallon tank. Maybe I'm seeing a half a mile a gallon improvement with the tune.

ieatglue
11-28-2006, 04:43 PM
Make sure you inflate your tires. When it get's cold, your tires drop a few PSI :yes:

gordinho80
11-28-2006, 04:48 PM
now that you all mention it...my tires do look a tad low...

i'll have new tires in 2 days and i work from home the rest of the week so the TB will be sitting in the driveway for a few days...will be sure to properly inflate new tires...

rbarrios
11-28-2006, 05:32 PM
yup I just checked my tires sunday morning after sitting all night.
26 psi is what I found all around. I bumped it up to 31. Doorjamb specs 32But I also noticed a slight decrease in gas mileage with winter fuel.

alvin@pcmofnc
11-28-2006, 05:51 PM
yep, along with winter blends come cooler temperatures for those tires to sit at.

I have tire pressure monitors in mine. The other day I came out to it and the right side was 33 and the left side was 29. Reason? The sun was shining on the right side I guess. I drove a couple miles and both sides leveled out.

Spong
11-28-2006, 05:52 PM
Another vote here for tire pressure and or wonderful mileage killing Ethanol garbage gas.

Another thought might be if you got K&N oil on your MAF wires? :undecided

Dave
11-28-2006, 06:26 PM
Blame it on cold temperatures and winter gas blend. You also get to pay more for the gas since the companies like to share the expense of switching over to the winter blend.

gordinho80
11-28-2006, 08:02 PM
Another thought might be if you got K&N oil on your MAF wires? :undecided

not an issue...cone was removed and sat to dry for at least 30-45 mins after oiling...

pretty sure its winter blend and the tire pressure

ScarabEpic22
11-28-2006, 09:38 PM
And remember only late 05+ I6s have a MAF anyway. Your 04 will not. Clean the throttle body after the techron if it doesnt help.

Turboslacker
12-29-2006, 09:14 PM
I just bought a 2003 Trailblazer with 51k miles. It was getting worse mileage than my 180k mile 1996 Blazer. Then I discovered the fuel filter was still original stock, never changed :crazy: Put in a new GM one and much happier :D

bullethole
12-30-2006, 02:28 PM
Tire pressures drop one pound for every 10 deg. of ambient temp. If the last time you checked TP it was 70 deg. and now it is 40 it will drop as much as three lbs. The previous post was correct that the sun shining on a black tire will raise the pressure slightly. I check mine early in the morning when it is cold so everything is maxed out and consistent.

PDiddy
12-31-2006, 03:17 AM
Fill your tires with nitrogen, I did and my tire pressure (40 psi) hasn't changed in over a month!!

ds8
12-31-2006, 10:08 AM
Fill your tires with nitrogen, I did and my tire pressure (40 psi) hasn't changed in over a month!!

I filled mine with air and the tire pressure hasn't changed in two months. Nitrogen is a gimmick...N2 is still a gas and will behave similarly to air. The temp has remained farily constant over the last month. That's why your tires are still at the same pressure, not because you paid $5 to have them filled with N2.

PDiddy
12-31-2006, 12:18 PM
I filled mine with air and the tire pressure hasn't changed in two months. Nitrogen is a gimmick...N2 is still a gas and will behave similarly to air. The temp has remained farily constant over the last month. That's why your tires are still at the same pressure, not because you paid $5 to have them filled with N2.

Well, that works for you, but in my case, my tire pressure fluctuated like a mofo with regular air. After less than a month, it would drop a few PSI. Now with the nitro, I don't have to worry about it. Do your research first................PS, I got it done for free :p

ds8
12-31-2006, 12:49 PM
Well, that works for you, but in my case, my tire pressure fluctuated like a mofo with regular air. After less than a month, it would drop a few PSI. Now with the nitro, I don't have to worry about it. Do your research first................PS, I got it done for free :p

I charge accumulators for suspensions with 99.99% nitrogen gas quite often for testing prototype systems. We have to add more nitrogen as the temperature drops to keep the same accumulator precharge that we had at the higher temperatures. N2 behaves the same as air.

Blazernut
12-31-2006, 02:17 PM
This is a never ending argument and it goes on forever as we all pull quotes from our favourite experts. :D

“Probably the greatest help nitrogen can provide to the average driver is that it dissipates more slowly through the inner liner and tire than air and therefore assists in maintaining inflation pressure,” said Phil Pacsi, executive director of consumer tire marketing for Bridgestone/Firestone. “It is the inflation pressure in the tire that carries the load, so a loss of pressure translates into a loss of load-carrying capacity. That can result in overloaded tires and tire failure, so this is very important for the average driver.”

Toyo sponsors the Speed World Challenge racing series, and Proxes tires are used in the Touring and GT classes. The tires are filled with nitrogen—a trend in both racing and in street-performance tires—which provides more stable inflation pressure.

For performance applications, however, nitrogen inflation may provide even more significant benefits.

“Primarily because it is a dry gas, nitrogen also reduces pressure build-up due to operation,” Pacsi said. “Air typically contains water vapor, which will increase the pressure in a tire three to seven psi as it is heated, depending upon driving conditions. Because nitrogen contains basically no water vapor, the pressure build-up due to heat is minimized. Therefore the tire’s hot pressure is very similar to the cold-inflation pressure, with much less input from the driving conditions. That means enthusiasts can set a cold pressure and more accurately predict the hot pressures, regardless of usage conditions.”

I love this topic! Creates great debate, :hijacked

B.