96 grand car.fuel economy...oxy sensor????

[roonie]

I have a 96 grand caravan with 200km/3.3 engine.the fuel economy has never been great.....15mpg in the city 18mpg hywy.this is when its warm weather.when it gets cold the van gets much poorer fuel mileage and when its really cold it really eats gas!
My question is what fuel mileage should i expect from a 3.3 that runs really well?
Can the oxygen sensors cause poor fuel economy even if they are not bringing up codes?I have talked to dealers but they,as usual, want to start looking which can be expensive.
should i change the oxy sensors anyway?some say they either go bad or they do not.
I go through a tank of fuel sometimes in 4 or 5 days and we do not do that much driving at all.
what other things can cause this fuel consumption problem?what else should i check/change

[GTP Dad]

Yes, change the O2 sensors. Especially if they have never been changed. Fuel economy will suffer greatly with an aging or bad sensor although you may never see a computer code. You can do the job yourself and save some major dollars. Other items that can cause this type or problem are cold weather, bad or aging plugs, bad wires, dirty air filter. Start with the sensors and see how that goes!

[murph7727]

I agree with GTP Dad, change the sensors. It should definetly help. The other items he mentioned are also correct but they will have a much more suttle effect on gas mileage. I would also change the plugs and wires just to know that they are up to date. Even if they aren't that old it will still help with the overall performance of the vehicle along with your gas mileage. Happy fueling!

[roonie]

my plugs have just been changed.the old ones were original and not in too good of shape.Tell me,the wires have a couple of digits on them that say ....4 95....is this the manufacture date of the plug wires?also what brand of 02 sensors should a person purchase as i have heard that some brands are of poor quality?I live in Canada so the brands may be different in the USA.

[GTP Dad]

Most O2 sensors are good as long as they aren't Bosch. I have heard the Bosch sensors are not very good. The 4/95 probably does indicate the manufacture date for the wires. Most wire sets are as good as any but make sure they meet OEM specs.