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How can i get better gas mileage in my 03 Trailblazer LS

23K views 26 replies 12 participants last post by  keith81 
#1 ·
I have a 03 trailblazer with a 4.2liter 2wd. I can drive 40 miles and burn $10.00 which gas is $3.30 gal. that is all on the highway around 65 mph. I know suv's are not great on gas but i think i should get better than this. If anyone has any ideas that would help me please let me know. Cold air intake or anything. Im not sure what i need to try.
 
#3 ·
Without spending money on anything new, try cleaning your throttle body.

This thread explains the process with impeccable detail: http://forums.trailvoy.com/showthread.php?t=51619

Disconnecting your battery during the process will reset the computer.

Your TB learned to run with the current state of the throttle body, ann will relearn with a cleaned throttle body.
 
#4 ·
:iagree:.. or you could just trade it in for a Prius :crackup::crackup::crackup:

but seriously... the throttle body would be the first place i would start... a can of cleaner costs about $4-$5 bucks.. cant beat that...

after that if you want more mileage.. then you dive into mods such as the PCMforless tune, e-fans, etc...
 
#7 ·
:dielaugh::dielaugh: :rotfl:

Hrmm... Let's buy a 4500 pound vehicle that's designed to cut through the air in the similar fashion that a cinder block does and then complain about MPGs.

Really? :weird:

I invite ANYONE who's got a TrailVoy and whining about MPG to pay for the (premium) gas an SS drinks and then contemplate life a little. :coffee

BTW, I've never whined about my MPG. I bought a 400HP V8 powered brick. I expect it to drink like a relapsed alcoholic at an open bar. :D


... though, cleaning my throttle body should be put on my to-do list. :undecided
 
#14 ·
well 1st of all im not wining about anything. another thing is i have seen where all kinda people are getting 18-20 miles gallon and wanted to see some ideas to get better mileage. if i had a 400hp motor then i know what to expect. with a v6 in a tb i thought it might be better than im gettin.
 
#8 ·
I owned an 2002 rear wheel drive TB LS new and never seen better than 250-260 miles out of that 18 Gallon tank. That's about 14 MPG. It looks like you're seeing the same fuel economy burning 3 gallons for about 40 miles. The numbers were better for me on the highway but not by much. Now, I own an 06 AWD Buick Rainier and have always see at least 21-22 on the hwy and around 16 in the city. Since installing a custom air intake, changing the plugs, replacing the brakes, and changing out all the lubricants (trans case, differentials, ATF), I noticed a bump around 1.5 - 2 MPG (both city and highway). No tune yet but soon. If I can muster 25 MPG on the highway and 19 city after a PCM tune, I'll always have a smile on my face driving my Rainier. :woot::woot:
 
#13 ·
I owned an 2002 rear wheel drive TB LS new and never seen better than 250-260 miles out of that 18 Gallon tank. That's about 14 MPG.
Something seems wrong there. I have a 2002 TB LS 4x4 and get at least 300 miles in a tank. Usually around 17-19mpg each tank, if I do all highway I'll hit 20 pushing 21.

To the OP - what does your temp gauge read? You could have a t-stat sticking (common issue) which isn't letting it warm up fully.
 
#9 ·
If anyone has any ideas that would help me please let me know. Cold air intake or anything. Im not sure what i need to try.
Start with the above mentioned throttle body cleaning w/battery disconnected. Since it's an '03, you might consider replacing the upstream oxygen sensor at the same time. It's also possible that the cat is clogged.....a good repair shop should be able to do a flow test through the exhaust to check it.

How old are the spark plugs, air filter, fuel filter? Do you keep the tires inflated to factory specs? Is the vehicle full of heavy junk for no reason? Is the A/C turned on a lot?

How often do you run a can of fuel injector cleaner? (Chevron w/ Techron is the best) Should be done every 2-3 months or so.

Cold air intake will do virtually nothing for mileage, regardless what some people will tell you.....save your $$ there. Jackrabbit starts, and screeching to a stop at lights and stop signs will all lower mileage.
 
#10 ·
Start with the above mentioned throttle body cleaning w/battery disconnected.
I recall a post recently from Roadie spelling out the mechanics behind a functioning throttle body. http://forums.trailvoy.com/showpost.php?p=1114687&postcount=426. I'm in similar agreement in that when your throttle plate is opening on acceleration (or open at a constant velocity), carbon and dirt buildup will have minimal impact on fuel savings. At idle, yes, there can be some performance issues. But overall, when tb butterfly is more than cracked, there would be minimal efficiency loss. My truck purrs like a kitten idling though! :thumbsup:
 
#16 ·
The temp is normal its around 190-200. I have talked to several people who say they get good gas mileage on theres. I have replaced the plugs, wires, fuel filter, flushed the trans completely (cooler also), checked tire pressure, I have done all the stuff i can think on it except for cleaning the throttle body. I rebuild transmissions and have not had time to get it in the shop and clean it yet though.


I know in the vehicles with a security radio unhookin the battery will lock it. I dont know if the TB has a radio like this in it or not. I have unhooked several here at the shop to pull the tranny out of it and locked the radio. Then i had to take it to a dealer to unlock it for about $50.00 . Does the trailblazers not have that type radio in it?
 
#18 · (Edited)
The temp is normal its around 190-200.
That's not normal. 190 is far too cold for the I6. Your temp gauge needle should be on 210, or slightly to the left of 210 but "kissing" the 210 marker. Any less and its running too cold. Its not uncommon for an older TB to have a thermostat that is stuck open. The system will try and make up for it and will seem to run fine. But it'll eat more gas and eventually clog up your CAT. It very often will NOT throw a code. This is what happened to mine. A new CAT and new thermostat and all has been well since.
 
#20 ·
it also seems like it kinda stalls or is sluggish sometimes when you take off. when i pull out of the driveway at home there is a pretty long hill i have to go up and it seems like it does not have all the power all the time. I have mitchell1 on demand 5 on my shop computer and it talks about a fuel injector balance test. Have you ever done one?
 
#22 ·
Yeah 190 is too cold. Sounds like a classic stuck open t-stat. People have recommended replacing the temp sensor at the same time as the t-stat since they are so close to each other and it is a bit of a bear to get in there in the first place.

Do those first, worry about the cat later. The cat may still be fine.
 
#25 ·
I will replace the thermostat and the temp sensor. I do not know about the gear ratio size but i think its a 3:42. I will look tonite and post back when i get home. I have not looked yet but do you know what and or how many gaskets have to be replaced to clean the throttle body?
 
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