I have a 97 z28 with 113k miles on it and it does run good but i am having gas mileage problems. Ive changed all the fluids/filters/plugs/wires/pcv valve/used seafoam/ and a few other things. I got some boltons and switched from a 160 stat to a 180 stat. I am getting about 13mpg driving suburban. I havent had a good chance to see how well it is on the highway. I don't lead foot it too much.

Well i was wondering if new o2s would make a difference or not? They may very well be the original ones in the car. Is there a good way to test the o2s without taking them out or is there any way to clean them?

 

At that milage, I would buy new ones.

You can get both for about $80-90 from www.gmpartsdirect.com if I remember correctly. It's only the front two that will affect your gas milage.

Dan

 

We all hate to buy parts that don't add Hp... but changing the 02's needs to be done... I went down to autozone and dished the cash out to get them...at 55K miles...it was a good decision, because my car is now running properly.

at 113K I'd recommend a change... Pull one out and see how it looks... if it's red...time for a replacement.

 

Reading the O2 sensor voltages using a voltmeter or scan tool/data logger would be the best way to verify if they are responding properly. The appearance of the sensor itself is not always a true indicator of its overall condition.

 

If they looked like mine did they are.

 

It makes sense to replace the O2s at this point, especially with new plugs and wires. When I changed plugs recently I found all four on the passenger side had gaps of .065 or higher. May have been related to a faulty O2. With all the tune-up maintenance you've done already I would for sure change the O2s.

 

As I have not done this - any instructions on how to?

 

Get the correct size wrench a yank it out. It will be tough, soak it with WD-40 or PBBlaster first. They are in there good!

Are there any differences in brands of O2's?

What are the correct 02 Sensor voltage levels, around 4.5X right?

-Dustin-