Got my good mileage back!

[billcu]

My green Mark has been losing miles per gallon lately.

I first noticed it during my drive to Carlisle this June. I usually get around 30 mpg on long expressway trips. This year it was 28 and it's been getting worse since.

I suspected the O2 sensors, and a few weeks ago a check engine light confirmed it.

I usually work on my cars myself, but I can't seem to get at these sensors. Once again, I have to thank Jeremi for installing them for me. He also put the new O2 sensors on my red Mark years ago when I first met him.

The car never ran bad, the mileage just suffered.
I've gained a solid 4 mpg increase in fuel economy back.

The car has around 185k miles on it, and it looked like these were replaced at least once before.

If your mileage seems to be getting worse lately, you might want to replace the O2's.:big-grin:

 

[k9t8m]

That'll do it...

 

[95blklsc]

Yea they can be a pain sometimes. I should check how long it has been on my 95, it might be time to do them again, at 160k now...

 

[Roadboss]

Great reminder of how important maintance is on our cars for them to produce what's expected of them. Thanks for the reminder Bill !

 

[Trixie]

I have GOT to get my car in shape, and then take her to Lonnie for a dyno tune or something. She runs so rich, the best mileage I can get out of her is highway about 21-22.

 

[whiplash15]

Gees Trixie. I get up to 26.5 on cruise at 75-80 with my CE. At one time I got 30.8 with my 94.

 

[Trixie]

I know, she is and always has been a gas hog. Then again, I stop frequently and have a bit of a heavy foot.

 

[driller]

She runs so rich, the best mileage I can get out of her is highway about 21-22.

Dang, I can get that and more out of the '93 with 4.30s! LOL, and to think I thought I needed to replace the O2's.

 

[Roadboss]

Yea even Whiner gets 20 MPG on the highway. "Get ur dun " Trixie !

 

[Misanthropy]

can bad o2 sensors cause surging ?

 

[billcu]

can bad o2 sensors cause surging ?

If they're bad enough they can cause some some misfires and 'stumbling' sometimes, but at that point there would be a check engine light. That's what both of my cars did eventually.

 

[BlackIceLSC]

Bill...that's exactly what happened to my 94. 170k miles on it at the time...and it was netting an average of 27 mpg, when I can usually avg about 31.

I slapped a new set of O2's in just because...and sure enough, the mileage went right back up.

Of course, I did this when gas was $4.50/gallon, so the cost of the O2's was a good investment. Now gas is $1.85/gal, so...whatever...at least the 94 is still chuggin along.

181k now, BTW.

 

[billcu]

Yeah, the difference is hard to believe. The mileage was going down gradually, and all of a sudden it's back where it should be.

My odometer reads 183,142 miles now, but it's been reading that since it stopped working this summer.

I actually want to fix that.

 

[driller]

can bad o2 sensors cause surging ?

You may want to try cleaning the MAF and check for a vacuum leak.

 

[BlackMark8]

It is seriously amazing how a 15- 16 year old can get 32 mpg highway. Brand new 4 cyl barely get that. These cars are way ahead of their time.

BTW i thought 02 sensors CANT cause misfires ! Maybe my 97 just needs new o2's !

nah there is no compression on that cylinder.

 

[billcu]

I'm not sure if it's really a misfire, but it's definitley a bucking or stumble.