Better gas mileage from a 2002 Chevy Trailblazer

OK,

What you need to change is the mass air flow sensor and the air cleaner. andy granatelli mass air flow sensor, air raid after market air cleaner system. this will give you better mileage and horse power to start with. then i would go with a hi flow catiletic converter and new exsaust. all together you should see about 25 to 50 horse power differance and 20% better gas mileage.

It must be in a pretty crappy state of tune if you can get 25+ extra hp and 20% better fuel econmy....
Maybe that explains why the US auto industry has gone down the tubes .
(This isn't anti US... the Brit industry went long ago.... so don't shoot the messenger)
Del

the gas mileage is poor...
I'm thinking of putting a...few more ponies under the hood.

Maybe you should just trade it in for a Sherman tank and forget the gas mileage.
Del <Slaps furry head with paw>

Just out of curiosity, are you sure it's a 4.2L and not a 4.3L??

Make sure it's fully tuned up, plugs, wires, PCV valve, intake, exhaust, O2 sensors, Catalytic Converter, Injectors/Throttle body Etc.

Also, scan the Computer, with a real scanner, that checks all sensors in real-time, while under load, to pinpoint any poor readings from any sensors. Sometimes mileage can be killed from 1 faulty sensor, and it may go unnoticed, and not cause the "Check Engine" light to illuminate. The only way to find any poor performance causing sensors is to do a "Live" test, and get the actual readings from each sensor.

Changing out the chip will certainly give you more horsepower, but I expect it will give you even poorer gas mileage. But redoing the intake, having the head polished and ported by someone who knows what he is about, and putting in something like a K&N intake and filter kit will certainly improve the "breathing" of the engine. They advertise a 10.85 HP increase at 5474 RPM for your specific model.

What mileage are you getting? Your trailblazer is advertised to get 16 city and 22 hiway. How are you checking your mileage? Only expect poorer mileage from the chip and a broken engine, altho you will get better performance for a while.

the sarcsm is free.......

You need chip tuning for petrol mileage not HP!! This will probably slow your truck down a tad, but give a far better mileage......

Some companies here do that as well, have a search around on the web where you live.....

You might even call it a "Tune-Down".....

All the other compnents need to be in first class running order to achieve anything usefull - plugs and ignition system.

You might be able to go down a petrol grade with the correct chip......assuming you are not already using the cheapest....

Trick chips can boost power and mileage.

Remember that with these new electronically controlled engines, the power is available on demand, not constantly. The problem stems from trying to build one engine for all applications, and building it as cheaply as possible. There are plenty of after-market chips, some of which can be custom programmed with a laptop. Improving air flow both in and out of the engine can only help. Remember that James Howden discovered that if you controlled the air into and out of a boiler, you could get more work from your fuel. An internal combustion engine is a heat pump the follows the same principles.

I had several cars in my youth that I improved both power and gas mileage by advancing the timing by 6 to 10 degrees over book and running premium gas. I know of several people who have installed better intakes and chips to get both more power and better fuel economy.

What needs to be done is to determine what improvements need to be made under what driving conditions. Then start exploring options in magazines that support that particular venue; 4 Wheel and Offroad, Road and Track, Street Sheet, etc.

http://autos.aol.com/cars-Chevrolet-TrailBlazer-2002/available-trims

Your truck's fuel poor consumption, is mostly due to its high weight. Check the link above and you can see that it weighs 4400 to 4600 pounds. Back in the 1980's the smaller Blazer truck may have weighed 3200 pounds - but was not as comfortable or crash-worthy of course. With the heavier truck simple physics is at work, especially in city driving. Fuel consumption is linearly proportional to weight, when the exact same driving approach is used.

You can do a few simple things (like the hyper-milers) and mostly avoid accelerating quickly and then following up with hard braking which turns your kinetic energy into heat very soon after. Harsh driving is proven to increase fuel consumption by 30% or worse.

Also see: http://www.eartheasy.com/live_fuel_efficient_driving.htm

1) Buy and install a Scangauge II. This will help improve your driving habits and provide you with accurate engine temperature.

2) After installing Scangauge II, experiment with blocking the grill. 30% of the drag on a vehicle is from pushing the air through the radiator. The Arizona heat will determine how much of your grill you can block during each season.

3) Join a site like Ecomodder and track your gas mileage. My 05 Lancer is up to averaging 36 mpg when it is only EPA rated at 30 with just an upper grill block and a cold air intake. I don't do or suggest the crazy stuff like drafting or EOC (Engine off coasting).

4) Another suggestion is to place a belly pan to close off all of the open spaces on the bottom of the truck. The back bumper is like a parachute on most vehicles.