Poor gas milage, no codes

[boat]

This is perplexing to me. I have a 94 3.2 MTX, I drive it a little spiritedly, not driving like an idiot cutting everyone off. By the way, I did search, but having difficulty finding an answer.

On my last fill up, I had less than 14 mpg. All in town driving.

I am getting pretty crappy gas mileage, but I have NO codes. Is it possible for the 02's to be bad and not throw codes? The suspected O2's have maybe 20k miles on them according to the receipt stack I got when I bought my SHO a year ago.

When I did my upper 60k back last July, I made sure to gap my plugs in the middle of the .042 - .046 (decimal point may be off). Fuel pump and fuel filter were changed new about that same time. I have only put about 6k miles on the car since then, maybe a little bit more.

I am NOT down on power either, she has plenty of kick in the pants response.

What else could be a contributor to the poor gas mileage?

EDIT: I run premium gas. On the trip back from Frankenmuth on 12-19, I got about 25ish, combined with some city driving prior to the trip.

 

[wjayg]

Gas mileage

I keep my receipts for fuel/mpg

1990 SHO MTX w/ 97K miles

Before upper 60K service w/ new AGSP 32PP plugs, new wires, new o2 sensors, new thermostat.

Worst mileage was 15.46 mpg with my foot into it

Best was 23.82 mpg

After 60K

worst: 15.39
best: 21.37

but that is always w/ my foot in it & no long road trip like before

 

[sperold]

The cold weather contributes to poor gas mileage, but the biggest culprit is your 02 Sensors. Replace them with new Motorcraft units. I found the other brands to be very shakey. Buy them yourself to make sure that is what gets installed.

 

[rubydist]

Yes, it is possible for the o2 sensors to be bad w/o throwing codes. The pcm will allow +/- 25% adjustment on the fuel trims before it trips the cel. The o2 sensors nearly always go bad by seeing the mixture as too lean, which means it will richen the mixture by ~25% before it throws a code. By that time, mileage will be in the tank.

ps, unless you hear ping on regular, save yourself a little money and use regular.

 

[stangeater]

Could be the 02's. I also suspect your right foot may contribute to your problem.

 

[LJRuddy]

I vote to change your 02s. Although the mileage that you are seeing is similar to what my 95 mtx gets in the winter with my heavy foot and city driving. I usually average 14.8-17.1mpg in the city. On the highway though, I get double that.

 

[zak]

How far does your temperature needle move up when warm (e.g. which letter in NORMAL doews it reach)?

 

[boat]

I will most likely replace the o2's, but I am going to give a little more time and see what happens, see just how much of my right foot is causing my poor mileage.

Yep, at times I would agree with that. But, I have been pretty easy on it with the slippery winter roads around here.

Could be the 02's. I also suspect your right foot may contribute to your problem.

It usually is around "M" and "A" of NORMAL, since I have changed the thermostat around Thanksgiving last year. One morning on the way to work driving at like 15 to 20 mph, it did rise to "O", (after the thermostat was replaced), but has not done it again since.

How far does your temperature needle move up when warm (e.g. which letter in NORMAL doews it reach)?

 

[bubba]

lol....Boat put his right foot into it! He's pretty easy on it some of the time.... But he drives like 10 over the limit though.... I would agree that the o2's are bad, as should replace them with "new" stuff!

 

[itwonder]

Cold wx + winter gasoline formulation = poor mileage.

 

[1995mtxsho]

Cold wx + winter gasoline formulation = poor mileage.

What he said. Sounds normal to me and my 95.