98 Lesabre O2 Sensor

[swipter]

I was reading another Park Avenue post about changing his O2 sensor. He said his mileage improved. My mileage has gotten pretty bad. I used to get almost 30 mpg on trips now I get around 24. My engine is not throwing any codes. Is it recommended to change the O2 sensor at intervals based on mileage or do you wait for it to go bad? I have about 100K on it now. I found where it is. Is it difficult to remove? Do you need a torch or heat gun break the seal?

Thanks

[BIG-L]

Is it recommended to change the O2 sensor at intervals based on mileage or do you wait for it to go bad?I found where it is. Is it difficult to remove? Do you need a torch or heat gun break the seal?

Ive herad any where between 60,000 to 75,000 miles or 5 years.

You need a GM O2 socket to remove it and when replacing it make sure you use some anti-seize on the threads.

The one that seems to decrease mileage is the one in the rear exhaust manifold next to the firewall.The hardest part is to get the harness removed from the engine bracket.Please dont use any other O2 then the AC-Delco AFS-109...Ive read about alot of problems with Bosch O2s.

If your getting bad mileage have you changed the fuel filter,spark plugs and PCV ????....Id start there before replacing the O2 and see how those help with your mileage.Ive also read where a complete tune-up on newer cars includes, fuel filter,spark plugs,wires,PCV and O2 .

~Larry~

[swipter]

I have replaced the plugs and wires and fuel filter has 30K on it. Unsure about the air filter but there was no difference when I changed it last time. I didn't know the PCV would effect the mileage. That is easier than the O2 sensor. WHy the need for the GM wrench? It looks like a standard large hex wrench would work?

[swipter]

BTW, I did remove the PCV valve and shake it and it still shakes. Can it be bad if it still shakes?

[BIG-L]

It looks like a standard large hex wrench would work?

It's a socket with a split down the side for the harness on the end of the O2.

BTW, I did remove the PCV valve and shake it and it still shakes. Can it be bad if it still shakes?

If it still rattles it should be ok,most of the time I just use some carb cleaner and spray it out.


~Larry~

[swipter]

Thanks, I will probably replace the PCV valve anyway. It is a cheap part.

[swipter]

I changed the PCV valve and it seems to run smoother and quieter. I am testing the gas mileage to see if there is any improvement.

[93buicklesabrelmtd]

PCV (positive crankcase ventilation) valve deals with how the car idles..
it should not increase gas milleage

fuel filter if it still worked, then you can NOT expect to gain extra milleage.
my original ac delco fuel filter was changed with 230k on it.
and it still blowed like the new filter i was replacing it with....

the best way to increase your gas mileage is to change your o2 sensor..
dont wait till it fails on you, then you will have a sluggish car. change your o2 every 60k miles..
my original ac delco lasted for 230k.. i replaced it with a bosch, but i also bought another ac delco on ebay.

all cars pre 1995..
o2 replacement is considered part of a tune-up
change every 60k. for best readings
slow reading--equals--- slow ecm input---equal---bad signal to fuel injectors--- equals--- wasted gas milleage..

[swipter]

I will say I can feel a difference in the idle since changing the PCV valve. It also seems to run smoother. Maybe it is in my head. I am checking my mileage now.