MX-3.com

I've been observing my mileage for the past few months, and I can't seem to get above 21.5 mpg no matter how I drive and what gas I use. My driving is mixed between city and highway. There are hills, but it's not too bad.

I tried 87, 89, and 92 octane gas, and I didn't notice much difference. Maybe 2 mpg max. I also tried driving as gently as possible, barely touching gas, and coasting whenever I could, and I still got 21.5 mpg. ZE with JE50 VAF and Probinator. New plugs and replaced O2 sensor.

I don't know how accurate the gas gauge is, but after filling up I get 80 miles from full to 3/4, from 3/4 to half I'm at 120, from half to 1/4 I'm at 175. My fuel light comes on at 215.

Ideas?

Transport Canada Fuel Economy ratings:

Mx-3 GS (K8 MTX) - 26 MPG City, 37 MPG Highway

I'm not sure how having the KLZE affects these numbers. Shouldn't you always use above 91 octane with a ZE??

you're doing better than i am. i'm getting about 18. mind you im in a small town so its drive a block...stop, over and over.

How in the world do you guys get 18 mpg on the ze... tune it up, ise 91 octane.


I used to get max around 30 mpg mixed hwy and city.

it's kinda obvious... change your fuel filter, ur plugs and wires, maybe tour o2 sensors and clean up your injection system and ull be doing much better

hharb wrote:it's kinda obvious... change your fuel filter, ur plugs and wires, maybe tour o2 sensors and clean up your injection system and ull be doing much better

I agree...

man people keep telling me to get a probinator chipped K8 ECU and that my kl-36 runs too rich but I am getting about 25 MPG on average with it and I run the crap out of my car daily... so what's the deal here?

i was running just as bad 21, or less on my ze and i changed my ecu did the injector treatment, and changed my fuel filter. i was originally running a probe ecu and i chipped a k8 and installed it on. man did it make a difference, i was running 30mpg, sometimes even more, but now its back to square one because my disty cap it broken and is apparently causing the horrible stutter when i accelerate. it shakes like a mofo, anyways she's getting all rebuilt and fixed up, but for moonegs, i would definitely try a chipped k8, its damn cheap anyways and you got nothing to lose, the only hard part is the installation, but u could always pm me for that or ask around. Also a tip, to calculate mpg, i fill up the car all the way, i run it for as much as i want normally till the light comes up, i fill it up again all the way, use the amount you filled the second time to calculate, not the first amount. its kinda obvious but some ppl dont know.

i get about 22\23 city with some hwy, thought that was good?, its been giving me that MPG since i installed my ZE with new Fuel filter, wires, sparkplugs, 93 octante

it depends what you mean by city driving, but i would say 23 is low, what kind of ecu, vaf combo are you running? i would say 25 is good, anything below could be eventually brought up...

boosted i get around 22 mpg and like 20 if i run way to rich. so yeah something is wrong if you are not boosted..

So, besides the plugs and the O2 sensor, what's the most likely culprit? Fuel filter and injectors? Could taking care of those two take me from 20 mpg to 30 mpg that some people here are getting? Sounds pretty dubious.

I think my HEI mod helped too... because I did air filter, wires, plugs, injectors, 02 sensors, fuel filter and the HEI mod all at the same time.

I think if my mileage was that far off from norm.. I'd try swapping out VAF's. Or at least check the shop manual and see if there is a test you can do on the VAF. My gut says that the VAF is telling the ECU there is more air present than there is so the ECU is juicing more fuel because of the erroneous reading. Dunno if this is correct or not.. but something to check if you can.

Tunes67

I get around 21-23 city with my K8, so I dont see how you guys claim 30+ city as it gets ~23 city brand new
http://www.edmunds.com/used/1993/mazda/ ... specs.html

I get about 22MPG in both Seattle and Chicago with ZE, which are both at approximately sea level. The only time I've ever gotten significantly more milage is when driving through Colorado at 6,000 feet elevation. Less oxygen = less fuel pumped in as long as you're not WOT.