Horrible Gas Mileage
 

I have been getting horrible gas mileage lately, i live in northern Wisconsin and i guess it doesn't help that it is in negative weather for 2 weeks or so, but i try to drive like a normal person and get the mileage that i should, but i don't. I live on a highway and drive 9 miles on a highway and then get into town and drive about 4 miles, everyday, i have no idea why it is so bad. Like now I'm below half tank and have not even drove a hundred miles yet :(

BTW there is no gas leak.

If you could maybe give me a few suggestions that would be great.

I was getting terrible mileage with my 2.2 when there was a problem with my o2 sensor.

I just discovered that my 2.2l has a cracked exhaust manifold...I will start a thread and post pictures later, but I am betting that is a huge part of my problem, it is likely related to o2 sensor readings regardless of what it is

Don't trust the gauge. Mine does the same thing.

You should get more than 100 miles by half a tank the gauge is unproportional but not by that much

Well i filled up yesterday and drove about 14 miles and the gas gauge already moved past the full line...like you could see the whole full line. Put it in my dads garage last night let it sit in the warmth for a night and well i think i smelt a little gas :( so I'm gonna have to look at it sadly....

Mine only use to get 100 miles on a full tank with the 3.4 now my truck gets 250 per tank with a v8 LOL if ya ever need help with installing anything or doing anything shoot me a message I live in the hustisford/ Watertown area and can drive! Jawa helped me out a long time ago so its my turn to return the favor and help someone else out

No codes I take it? Have you tried scanning for stored codes at all to see if something did pop a code and not illuminate the dash? There are a few in there that would be set to no MIL light from factory and you may find something if you check. Just an idea. Other than that, O2 sensor, charcoal canister, plugged cat, cracked manifold or a bitched MAP would be my first concerns. There are many reasons your mileage could go to hell, something as simple as a couple of fouled plugs or a set of boots or coils needing replacing could be it as well, even a plugged air filer!
Another one to check is the dam fuel pressure regulator, that is a common one too

I had this same issue but I have the 3.4. While tearing it apart to change the intake gaskets I noticed that my cam sensor wiring had melted together due to the power steering leak softening up the wire insulation. I also noticed a high amount of fuel line pressure when I let it out through the valve on the fuel rail. This leads me to think the injectors have been running wide open. I spliced in a new pigtail and my gas mileage is awesome once again. It's worth a shot to check your wiring to the cam sensor. It really seems to make a difference.

Our fuel control setup is considerably different from a 3400
http://www.ecotecforum.com/forums/sh...osition-Sensor
http://www.j-body.org/forums/read.ph...68262&t=368262

Coils in the 4 cly are a much bigger problem than most know too. It's another issue that for some dam reason the car will not throw a code but if you test them you may find a very different answer. The boots from coil to plugs do go bad contrary to what a lot of these forums will tell you. I spent 12 years driving the 4 clys and 6 different models in that time. I have seen it all bud...

some tips to help increase gas mileage(excluding mechanical problems)
1)check air pressure (i do 32 psi a tire)
2)change oil when you should, i run a oil additive,
3)if your carrying around dead weight or stuff the shouldn't be in the car, take it out of your car and bring it into the house
4) check air filter, most people run a K&N or some type of upgraded filter.
5) i keep the outside clean including keeping wheel well area free of mud and dirt(use a hose at a car wash for $2)

Fuel Pressure regulator
 

That is a cheap and easy thing to try. When blown it pulls gas into the engine through the vacuum hoses. Costs about $50.00. Put a rag over the regulator as you pull it out or you will get a face full of gas.

Check for gas in the hose leading from the regulator. If you pull off the hose and it smells like gas your regulator diaphragm is blown and letting gas through to the engine.

You can also put a clear piece of hose on the reg and do the "suck test". If any fuel shows up in the tube the regulators diaphragm has a tear in it and is done