Mazda MX-6 Forum banner

Poor gas mileage and loss of performance

879 views 7 replies 6 participants last post by  Stage36 
#1 ·
How many miles MX should run on full tank?
Earlier I reached 310 and even 320 miles before fuel warning steady light
Now it's about 230-240 miles :-((
Can O2 sensor make such big difference? I can't believe
Another problem is that car won't accelerate from 60-80 mph on 5 speed. I need downshift to 4th everytime when passing
I remember when I test-drove MX6 for the first time (not mine) I was impressed how it accelerate from 80 to 100mph on 5th
(much better than 626 with 4cyl). But my car don't :-((
Pls give me idea where to dig...
I changed all spark plugs, wires, air filter with no effect
 
#4 ·
O2 sensors are definite candidates when it comes to poor mileage. They can degrade (slow response time) over time without the PCM tossing a code. Have you pulled a spark plug? If so, what colour do you see?

Also, since you've got a 1993 model, check to ensure that the rear calipers are not seized and causing drag. How easy is it to push the car on a level road? Jack up each side and make sure each rear wheel rotates freely.
 
#6 ·
626butnotforlong said:
in 5 gear at 100Km/h (60Mil/h) my engine rev about 3000Rpm is it normal
Yes, it's normal.
 
#8 ·
if you havent done so sice youve purchased the car, do the fuel filter, O2 sensor, and check the cat. And like Mike mentioned, the spark plug should be the tell tale sign if youre having problems with stoichiometry, cylinder temp, etc...

you might wanna try a compression test as well to rule out a faulty ring/leaking head gasket, etc.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top