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2006 chevy trailblazer_lt
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Discussion Starter #1
I looked at an earlier thread in regards and it seems most 5.3 Trailvoy owners are getting better than my 10 MPG that im getting. I have an 06 with the 5.3 and 47k on it now. The Truck runs great and pulls strong, not sure if this is just as good as it gets or something has been neglected or ill maintained. I just got it and it was from a dealer so I dont have any info on previous maintaince records. My plan of attack was just to change out the Fuel filter and air filter and see where that gets me. I know its a v8 pulling a heavy truck but it should be doing better than my 89 vette with huge injectors and other such anti-gas saving mods, that at least gets 11mpg and thats with 80s tech under the hood. Again, sorry if this was previously asked or addressed, but all previous post didnt seem to help me in regards. Any replies offering suggestions are greatly appreciated, other posts telling me to deal with, "what did you think you were going to get", or otherwise general moching of me are less so appreciated. oh and Happy New Years to all, wishing you and your family a safe and happy holiday.
 

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2006 chevy trailblazer_lt
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I don't see what your rear gears are, and you don't say what kind of driving you are doing to get 10 mpg. So it is hard to comment.

Most of the points applicable here have been made in this thread:

http://forums.trailvoy.com/showthread.php?t=49362

In addition, I have never understood how a fuel filter affects gas mileage. My understanding is that within a wide range, the PCM "adjusts" for variations in fuel pressure. Same for a dirty air filter. The fuel injected is matched to the amount of air actually getting into the engine, so a dirty air filter won't affect fuel mileage, at least within a fairly wide range. If those two things are true, and I believe they are, then I would never start with a fuel and an air filter when trying to improve gas mileage on any modern vehicle.

I would start with a baseline. A two hour Interstate or turnpike trip, one hour out and one hour back, with cruise control set, and in mild weather conditions, to establish a baseline. Then I would do things to the truck and when I had done as many as I reasonably could, I'd do another baseline comparison.

Also, I would not use the DIC to tell me the mileage. I would do the actual calculation. Fill the tank full, drive it, fill it full again, then divide the number of gallons used into the number of miles driven. Hard data is what you want.

Were it me, I'd start by replacing the O2 sensors. Then I'd replace the coolant temp sensor, assuming your thermostat is working properly. But I'd probably replace that just to make sure. Just my thinking.
 

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2005 gmc envoy_denali
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My 5.3L gets between 15 and 18 MPG. Lately more toward 15 MPG with the cold weather. Winter fuel blends also don't help. Different brands of gas also could be a problem. Here all gas has at least 10% ethanol :mad: and with the cheaper gas prices may have more than 10% ethanol. :hissy:

My best mileage is with 100% gasoline, which doesn't exist anymore in OH. :hissy: F***in government. :x

The fuel filter on your truck is in the fuel tank. Not a cheap or easy change.
 

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2003 chevy trailblazer_ls
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My 5.3L gets between 15 and 18 MPG. Lately
My best mileage is with 100% gasoline, which doesn't exist anymore in OH. :hissy: F***in government. :x

I think the tree huggers are more to blame. They are the ones that push to get the ecology laws passed.
 

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2005 chevy trailblazer_ls_ext
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In addition, I have never understood how a fuel filter affects gas mileage. My understanding is that within a wide range, the PCM "adjusts" for variations in fuel pressure. Same for a dirty air filter. The fuel injected is matched to the amount of air actually getting into the engine, so a dirty air filter won't affect fuel mileage, at least within a fairly wide range. If those two things are true, and I believe they are, then I would never start with a fuel and an air filter when trying to improve gas mileage on any modern vehicle.
Thank you! I've been saying this for a long time. No one has ever really explained it to me. Yet many people around here instantly suggest "fuel filter" for complains about poor MPG. I don't get it!

I would start with a baseline. A two hour Interstate or turnpike trip, one hour out and one hour back, with cruise control set, and in mild weather conditions, to establish a baseline. Then I would do things to the truck and when I had done as many as I reasonably could, I'd do another baseline comparison.

Also, I would not use the DIC to tell me the mileage. I would do the actual calculation. Fill the tank full, drive it, fill it full again, then divide the number of gallons used into the number of miles driven. Hard data is what you want.

Were it me, I'd start by replacing the O2 sensors. Then I'd replace the coolant temp sensor, assuming your thermostat is working properly. But I'd probably replace that just to make sure. Just my thinking.
I also agree with this 100 percent. Personally I changed my spark plugs at about the same mileage as the o/p is at. Yes everyone including GM states the plugs are good for 100K miles, but I lost a lot of performance by 40K miles.
I have seen as low as 11 MPG on my EXT with the I6 - especially in the winter time. Yes winter here in Southern Ca. is not the same as it is on other parts of the country/world, but it still gets colder than summer.
In the winter time, people tend to let the engine "warm up" a little longer. Plus it takes the engine a little longer to get to operating temp. My 11 MPG happens on my morning commute - especially when traffic is heavy and I spend a lot of time idling. Idling is a definate MPG killer! But then so is a heavy right foot! :D
 

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2006 chevy trailblazer_lt
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Discussion Starter #6
The milage estimate I posted was given after filling my tank all the way, driving the car down to a quarter of a tank, and doing the math based on miles driven. I did this for about 5 tanks of gas with mostly around town driving, with some highway mixed in. As far as rear end gears I havnt had the change to look up my RPO codes on the vehicle yet. Thanks again to all of those who replied.
 

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2005 chevy trailblazer_ls_ext
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The milage estimate I posted was given after filling my tank all the way, driving the car down to a quarter of a tank, and doing the math based on miles driven.
Either you left out an important step or you are doing it wrong.

Should be - fill the tank, drive down to a quarter of a tank, refill the tank and THEN do the math based on the amount of gallons on the second refill.
 

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2006 chevy trailblazer_lt
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I can see how mostly around town driving would give you 10 mpg. Remember too, your truck is 1500-1800 lbs heavier than your Corvette, and it takes a lot more gas to move that extra mass.
 

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2006 chevy trailblazer_lt
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Discussion Starter #9
im not sure I get what you mean, I did my calculations based on repeated trails over 5 full tanks of gas to achieve a more accurate sample. In any event, If that mpg is what everyone else seemed to get, I wouldnt say anything, I just dont get why it seems so much lower than anyone else, even my old yukon with 5.7 litre TBI got better milage than this, and it was a heavier truck than my TB. Some people replied saying to look into the plugs and O2 sensors however they both are rated for 100,000 mile service interval and at upwards of $150 for an 02 sensor its not the price range to just swap out on a whim.
 

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Some people replied saying to look into the plugs and O2 sensors however they both are rated for 100,000 mile service interval and at upwards of $150 for an 02 sensor its not the price range to just swap out on a whim.
Just because parts are rated for a particular service life doesn't mean every part lasts that long. Just doesn't happen.

I'll bet the O2 sensor doesn't cost anywhere near $150 for your truck. But even if it does, how long would it take if it improved your gas mileage by 5 mpg to pay for itself?

We don't offer advice on a whim. We have experience and knowledge to back up our recommendations. You asked for our advice, but because it is expensive, you don't want to take it.

Ok, that's fine. Take it to the dealer and pay the mechanic to diagnose and repair it, paying list prices for the parts. Or don't try to fix it, and pay for all the extra gas it will swill.

We tried to help. Apparently you don't want our help if it doesn't agree with your wallet. So be it. But don't insult our intelligence or our recommendations or our knowledge.
 

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2002 chevy trailblazer_ltz
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...... or something has been neglected or ill maintained. I just got it and it was from a dealer so I dont have any info on previous maintaince records........
Go back to the dealer, and ask the service manager to pull the records for your vehicle. As far as I know, they can tell you what was done by a dealer. I know this doesn't help if all the service work was done by the owner or a private garage, but you might find out something useful (original owner complained of poor fuel mileage, etc, etc).

A couple of things come to mind to check. The above mentioned O2 sensors, how clean is the Throttle body, a plugged catalytic converter. Also, try disconnecting the battery for about 30-45 minutes to let the PCM reset back to factory default setting.

Hope some of this helps.
 

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2003 gmc envoy_slt
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At this point you can try a bottle of Chevron Techron to clean the injectors and intake screen in the gas tank. :m2:
 

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im not sure I get what you mean,
Very simple. You fill up the tank. You drive until - let's say the gauge has about 1/4 of a tank. Then you fill up. You take the miles you drove by the amount of gallons it took to fill up the SECOND time, not the first.

In your previous post you said "The milage estimate I posted was given after filling my tank all the way, driving the car down to a quarter of a tank, and doing the math based on miles driven."

That makes me think you filled up the tank, wrote down how many gallons it took to fill it - then drove until 1/4 of a tank and then refilled, but used the gallons from the FIRST fill up, NOT the second to figure your MPG. If I wrong correct me. That's what it sounds like to me.

There is no magic potion for getting better gas mileage. Like "markarock" said, you asked for our opinions, we gave them to you. I've had my TB for over 4 years.

Like I stated I know GM and others say you can leave the spark plugs in until 100K miles. At 40K mine were not doing that well. Kids on 10 speed bikes were leaving me in the dust at a stop light! :D For at least the first 30K miles or so I drove mostly freeway.
I changed my 02 sensor before changing the spark plugs. It helped a little but not much.
For the I6 the 02 sensors are about 50 bucks a piece and you really only need to change the one before the cat. converter. Rock Auto has 02 sensors for your truck from 35.00 and up. Since you have the V8, you would need two to change the before the cat. converter ones.

Also, as was mentioned you can't compare apples and oranges. Because someone else CLAIMS to get 15 around town doesn't mean you will. Road conditions, different gasoline, vehicle condition, tires, mods, driving habits ALL will have an impact on your MPG. Driving habits is pretty much the biggest one.

What another vehicle will do with a similar engine isn't even worth mentioning. There are too many variables. As was mentioned, vehicle weight, axle ratio, even the year of the vehicle will make a difference.
 

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2004 buick rainier
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winter driving

I can see how mostly around town driving would give you 10 mpg. Remember too, your truck is 1500-1800 lbs heavier than your Corvette, and it takes a lot more gas to move that extra mass.
Also they are shaped like a brick. My all time low was 12.5MPG a couple of weeks ago. These factors are to blame::m2:
15 degreeF weather
10 miles to work and short trips
extra warm up time
snowy roads
driving in 4WD hi
teenage driver(part of the trip)
slush build up
reduced hiway speeds due to the weather and so on........
Lately it is at 15.5MPG in 23 degreeF temp. and no snow.
Paul.
2006 5.3L TB 3.42 gears. 53k miles.
 

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2006 chevy trailblazer_lt
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Discussion Starter #15
um...what the hell is with all the hostility? all I was saying is I think there might be other options to explore before swapping out expensive parts hoping it might solve the problem. I am well aware not all parts make their life expectancy however to think a part rated at 100,000 miles would die after 47k is a bit pessimistic. Nobody is insulting anyone's intelligence or perhaps lack there of. Just because someone doesn't blindly follow your immediate instructions doesn't mean there is some sort of inherent disrespect nor does it necessitate you going off on a defensive rant.
 

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I am well aware not all parts make their life expectancy however to think a part rated at 100,000 miles would die after 47k is a bit pessimistic.
Actually, it's not pessimistic, it's reality. As I said I've had my TB for 4 years since it was new. I've been reading on this forum for about the same about of time. (Joined about 2 years ago).
Many of us "old timers" have seen a lot of parts fail "prematurely". Ignition switches, end links, water pumps, fan clutches - to name a few.

Personally I don't see any "hostility". You asked our opinion we gave it to you. If you don't like it, figure it out for yourself. But don't shoot the messenger . . .

BTW, there are NUMEROUS threads on this forum about MPG. Use the search function - you will have enough reading to keep you busy for quite a while!
 

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Today I drove from Wexford, PA (near Pgh.) to Leesburg VA. Temp varied from 9F at the start to 30F upon arrival. Total miles = 245.

Calculated gas mileage was 18.6 with cruise set on 70 nearly the entire way. Load was driver, passenger and 150 lbs of cargo.

When I was not on the Turnpike or Interstate, I drove as though there was an egg between my foot and the gas pedal, so I was trying hard to maximize gas mileage.

One thing I noticed was that the first part of the trip was very hilly, and according to the DIC my mileage was less than it was at the end of the trip in more rolling terrain.
 

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2007 chevy trailblazer_lt
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few things

First, I have the same truck only blue and grey, 5.3 V-8 g80 and 3.73 gears. Tachs about 2000 at 65 mph.

Now, during the cold months, the air intake temp sensor adds fuel to compensate for colder, denser fuel mixture. The DoD feature will only help you on highway mileage and some around town. The dod can be "felt" in the engine and I would recommend HIGHLY the dashhawk!!! It allows you to monitor your intake temps, dod status, fuel used, many other options.

Try not rapid starting on the highway, cruising at about 65 and warming the car up before the trips. Also, set the A/C compressor off (automatically runs it above 30* outside temp) by hitting the snowflake symbol on the hvac controls.

The average for mine is about 15 mpg during the winter. Highway, I can get 22-24 mpg on a steady road, NO CRUISE CONTROL!!! Dont use it...it kills the gas mileage!!!

So, these trucks should average 15 highway and 12 city during the winter months if its real cold (12* in Jersey!!!)

Don
 

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..... Also, set the A/C compressor off (automatically runs it above 30* outside temp) by hitting the snowflake symbol on the hvac controls......
Not that it really matters, but I think the actual temp. that the A/C shuts off automatically is approx 37 degrees F.

I shut it off all the time, except for when I need A/C in the summer, or if the windows fog up. I'm pretty sure it has to be worth an extra 1-1 1/2 MPG with it off.
 

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Thank you! I've been saying this for a long time. No one has ever really explained it to me. Yet many people around here instantly suggest "fuel filter" for complains about poor MPG. I don't get it!
I have experienced a +4 mpg difference replacing a clogged fuel filter. I didn't have driveability problems, just a drop in mpg. The way I see it, the pcm would see lean o2 readings (due to lack of fuel volume) and increase injector pulse time to richen the mixture.

I change mine every 15K.
 
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