Only 14 Mpg? Got Codes, What Do They Mean?

[ForOffRoadDriving]

so my "new" 1994 ranger has about 1,000 miles on it and i filled the tank up for the first time so i could drive it all week and also to do a fuel milage test on it. i went through a whole tank of gas (14gal) in less than 200 miles. my mpg test turned up 14.5 mpg. keep in mind ive got 3.73 gears, 30" mud tires, a 150lb bumper and skid plate, and 3 hellas on top of my roll bar creating drag, but doesnt 14 seem very low for a fresh motor or should i be expecting lower mpgs because its still breaking in? i put my scan tool on it last night and came up with a KOEO code of 4095, undefined code; and a KOER code of 411, cannot control RPM during self test. i also viewed my live data and noticed that one 02 sensor was not reading anything while the other had readings that were varying, which as i understand is normal. i viewed the engine rpm and compared it to my autometer tachometer and noticed that the tachometer was about 600 rpm below the engines rpm data. is there a way to calibrate the tachometer or could it be resistance in the wires to the tach causing a delayed reading? hopefully someone can point me in the correct direction.

 

[Big Jim M]

A week long test driving in Michigan is a check of the daily milage to be expected on one cold engine after another. You done about average for a week long in town test.
If you really want to know the hiway milage you must take a tank or two test on the hiway..
Withthe hellas and the unusual shaped front bumper you prolly won't do the VERY best milage on the hiway either.
Big JIm

 

[Jay FX4]

I live in Michigan and I routinely get 18-21 city mpg out of my 4.0/auto trans/4.10 gears. You could probably tweak your driving style a bit to milk a couple more mpg's out of it. Have you filled it up more than once? I'd fill up and drive the tank empty at least twice, since your calculations are going to be for the previous tank.

 

[Jon4x4]

I always heard that once you rebuild a motor your gas mileage will take a few thousand miles til it kicks back up

 

[ForOffRoadDriving]

ok thanks guys, im going to try to figure out which sensor is not reading and swap in a new one, then ill run a couple more tests on it to see what kind of mileage im getting. I usually only drive country roads and occasionally i drive in the city (small town), so i rarely ever use the freeway to travel.

 

[oachs83]

The 411 is more than likely your IAC (idle air control) also if your timing is off or you have a vacuum leak it will set this code as well. The 4095 code must be a missprint? You should only have 3 digit codes on a obd1 system.

 

[ForOffRoadDriving]

thats what i was thinking but it said it was a memory code? like it was tripped once or twice but never became a Diagnotsic Trouble Code? im still learning how to use my tool and decode these codes, so please bare with me.

 

[ForOffRoadDriving]

i replaced the bank 1 o2 sensor and it didnt seem to make a difference, so now im thinking maybe its not getting any voltage since a closer look at my scanner shows a (v) next to the numbers. heres a few screen shots, ill go take a pic of the 4 digit code screen so maybe i can get some help with that.

the tahcometer data doesnt match as you can tell in the picture, while driving it is consistently off by around 500-700 rpm, but at idle its olny 150-200rpm difference.

 

[ForOffRoadDriving]

heres the two stored codes that i can go back and review

 

[oachs83]

Pictures do not work for me

 

[Jay FX4]

That's weird, the pics showed up fine earlier....

 

[ForOffRoadDriving]

Sorry guys, i exceeded my bandwidth allowance with photobucket, i t should be fixed on the 17th.

 

[Jay FX4]

Sorry guys, i exceeded my bandwidth allowance with photobucket, i t should be fixed on the 17th.

You could repost them with the "attachment" method...

 

[ForOffRoadDriving]

I fixed the tachometer today, there is a little switch inside the tach that has to be set for the proper amount of cylinders and me being a normal guy neglected to read the first page of the instructions, where it tells you to callibrate the tachometer! as for the idle code i was told by my co worker to check my throttle plate stop screw and see how far in it is screwed and also to check that the throttle plate is all the way closed at idle. it wasnt so i readjusted it and then cleared the codes out and ran the test again and came up with code 111 no codes stored, so i guess im fixed? my bank 1 o2 reading is still not showing voltage so im going to start back probing the white wires on the engine harness that feed the o2 to see when i pick up voltage.

 

[ForOffRoadDriving]

Ok, i ordered a new scanner today (an updadted version of the old one i was using) and now its reading the voltage of that 02 so now im all set!