MPG question

Short Answer is YES.


You are loosing all your MPG due to the O2 not being hooked up.

The computer needs the input from the O2 sensor because it's tells the computer how the mix is going. As soon as the computer does not receive the 0 to one 1 volt signal, it throws the CEL and goes into limp mode - it's best safe guess for what fuel it needs based upon the throttle position sensor and Mass Air (90 to 93) or MAP sensor (87 to 89). The limp mode is set rich to keep the engine from burning up in a lean condition. Much cheaper to replace spark plugs than an engine.


The O2 fine tunes the mixture to balance out the pulse of the injectors. When the computer sees less than 1/2 volt it pulses the injectors more (the lean side) and when it shows over 1/2 volt it leans out the mixture - this happens several times a second.

I have a 93 and an 88 Mustang - i drive the 93 daily - most highway but some city. I get an average of 27 to 28 with the ethynol crap they use here. I do have a 5 speed and i run an 8.8 axle with 2.71 gears - i get my best MPG in 4th doing 75 MPH at 2500 RPM. The 88 is a convertible and still sports the original 7.5 axle, and on my last road trip it got 30 MPG.

In short, you need to hook up the O2 sensor - it should remove the CEL. The O2 is before the cat originally, and having no cats is actually a benefit - it runs better and more power. I gutted both converters on both cars and it gained from getting 24 MPG to the 27 .

Get a 93 or 94 Ford Ranger exhaust manifold for a 2.3 - it's a factory header with the O2 bung in it. (95 to 97 Rangers are similiar but no O2 bung) The Ranger header will bolt in without having to move your current exhaust pipe.

Also, disable the EGR. The tube that runs from the exhaust up to intake isn't doing you any favors either. It's worth the effort to plug it up at both ends (but leave the electric hooked up). You can plug it up cheaply (or free) by undoing the pipe, cutting it in half, take a hammer and flatten the cut part of the pipe for about 3-4 inches, thentake some vise grips fold about an inch or so over and then hammer the bent part back to the flatten out part. do this for both areas and bolt them back into the manifold and intake.

If you still have the stock air delivery tube from the air filter to throttle body, there is a major restriction in the bulge area. you can remove the inner plastic parts of this by undoing the hose clamps and you will see an inner plastic 2 piece that can be pried out of both ends with a screwdriver, it takes a little effort to get it started, but once you get going, it pops out. It necks down the airflow to a little over a size of a quarter.

After you do any of the above, disconnect your battery for 10 minutes and let the computer reset itself and learn it's new found power.

Also forgot to mention. On my 93 I tapped into the O2 sensor feed to the computer and run an Air / Fuel guage. It's amazing how rich the car runs when you disconnect the O2 sensor - the guage almost completely pegs rich full time. Nice thing about having that guage in the car is that it lets you know if your O2 is good or bad.

The Mazda one is the same header. The header is the same for both Cal/ and non Cal manifolds. The difference is the california one had the EGR tube. The non California one has the EGR bung, but has a pipe cap on it. In fact my 93's header is off a 94 Mazda B2300 all I wound up doing was having to mod the EGR tube at the intake side.

Measuring Now

bonestock87 said:

I'd like to know how other 4-cylinder owners are doing. I'm always a little disappointed each time I calculate my MPG's after a fill up and end up between 21-22.

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My last tank came back at 14.161 gallons over 297.6 miles which works out to be 21.015 miles per gallon. Mind you, this last tank-full was driven with a bad coil pack and bad ICM so I was running only on 6 plugs not 8. I will report my mileage on this next tank-full. My 92 2.3L has a T5 (1352-162) and a 3.73 rear. More to come next week...

FVBonura said:

My last tank came back at 14.161 gallons over 297.6 miles which works out to be 21.015 miles per gallon. Mind you, this last tank-full was driven with a bad coil pack and bad ICM so I was running only on 6 plugs not 8. I will report my mileage on this next tank-full. My 92 2.3L has a T5 (1352-162) and a 3.73 rear. More to come next week...

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You should be getting more than that - i assume you must drive more city than highway? Can't wait to see your next tank results.

on a side note: 3.73 rear? Nice, is this an 8.8? I thought the stock 7.5 was 3.55ish?

I can imagine it jumps good off the line - I have an 8.8 with a 2.73 and well...it's ok. I used to have a Pinto back in the day with a 4.10 gear and light to light was fun with the V8 boys....

Delray Dude said:

You should be getting more than that - i assume you must drive more city than highway? Can't wait to see your next tank results.

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Yes city driving in Harrisburg, PA.

Delray Dude said:

on a side note: 3.73 rear? Nice, is this an 8.8? I thought the stock 7.5 was 3.55ish?

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As far as I can tell its a stock non-limited slip 7.5" 3.73:1 rear from the original A4LD setup. With the T5, I now can chirp gears and burn rubber.

I don't expect much better mileage than the mid 20's with those gears but I will keep tweaking her.

As a side note, I found this really good Ford Ranger site that addresses 2.3L mileage and performance improvements. It helped me get some more power out of my ride and I'm sure mileage has improved too.

Getting the most out of the Ford 2.3L

I plan to reduce my idle and make a custom 205 degree thermostat as was outlined in the above site. I will let you know if it helps.

Second tank was 297.1 miles over 14.287 gallons or 20.795 miles per gallon. I checked my tire pressure and three or my tires were very low. I will report the third tank with properly inflated tires but I suspect mileage in the mid 20's will require some new plugs, new wires, throttle body cleaner, and swapping out the T5 tranny fluid and the differential oil with synthetic fluids. I will keep reporting my mileage and what I have done to improve or worsen it.

More to come...

Sounds like all of you are doing better than me. I get around 10mpg in my 2.3. LOL. However, I'm running E85 on a really bad tune with 52lb injectors.

My 97 GT seems to actually do better on gas than my 2.3 did when it was NA and stock. The best the 2.3 did was around 18-20 around town and 24-25 on the highway. With the GT, I am getting 20-21 around town and 25-27 on the highway.

Delray Dude said:

Also forgot to mention. On my 93 I tapped into the O2 sensor feed to the computer and run an Air / Fuel guage. It's amazing how rich the car runs when you disconnect the O2 sensor - the guage almost completely pegs rich full time. Nice thing about having that guage in the car is that it lets you know if your O2 is good or bad.

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How are you getting an input to the gauge if the O2 sensor is disconnected?



My 87 would hit 27-28 very consistently... and that was low 8.* CR and worn to hell slider cam...
Check codes
Check cam belt/timing

vristang said:

How are you getting an input to the gauge if the O2 sensor is disconnected?

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I guess I should say that I spliced into the O2 line between the sensor and the computer - so both the computer gets the signal and so does the guage.


but when my computer went bad and the code scanner showed a faulty O2 I was able to see what it (the computer) was trying to do - and it went full rich all the time.

Improvement!

OK on to tank three. This is going to sound like a Public Service Announcement but keeping your tires properly inflated helps mas mileage a lot.

Tank three clocked in at 11.439 gallons over 304.8 miles or 26.646 miles per gallon. That is an improvement of almost 6 mpg from the previous tank-full. I plan to swap all the fluids out for full synthetic and I plan to buy some fresh plugs. I suspect upper 20's are possible on this car after this easy improvement.

You picked up about 6mpg with tire pressure?

vristang said:

You picked up about 6mpg with tire pressure?

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well sometimes. I had my pressures off on mine LF = 25, RF = 20, LR = 28, RR = 30. Got 23 MPG on that run. Adjusted all pressures to 40 PSI and MPG jumped back to 27 MPG.

My SVO averages 26mpg. My base model '94 Toyota pickup averages 28 with a best of 30. It also weighs about 300lbs less than either of my Mustangs. I haven't checked economy with the '68 because I'm not sure I want to know. My guess is ~12mpg because I drive it hard and the carb needs attention. The '89 GT I had before that would average 21 with a best of 24.

I'm seeing low 20's out of my '91 2.3/a4ld convert.

Finally found a local gas station that sells ethanol free gas......can't wait to fill my tank up later this week and see if I hit the 30 MPG mark. Been hovering at 26 MPG lately.