ford ranger 1990 4.0l

RonD · May 3, 2015

Try LMC Truck , select Ford Ranger and then "interior" search

alonsito0114 · May 4, 2015

ford ranger 1990 4.0 2" lift suspension

I really need help i drove my truck today and is giving me 10 mpg i dont get it ruuns good and everything has new spark plugs new cables new engine new water pump new baterry new termostat new temp sensor new tps it had a leak on the manifold and got fix plz help

RonD · May 4, 2015

2" lift........do you have larger tires and did you compensate for odometer being off because of it?

O2 sensors tend to make engine run richer as they get older, 100k is expected life span of an O2 sensor.
Slight misfires put extra oxygen in the exhaust, O2 sensor sees that as Lean burn so computer adds more fuel than needed.
Exhaust manifold leak does the same thing, sucks in air so O2 see Lean burn.

If you hear Cat converter making more noise than usual, that heating up metal expanding noise, then you are running rich.

Pull out a spark plug and see if it shows dark brown or blackish color meaning rich mix.

Check Fuel Pressure regulator's(FPR) vacuum hose, if FPR starts to leak that fuel is sucked into the intake.
FPR is passenger side front on lower intake, has the Return fuel line attached and the vacuum hose, check hose for fuel or fuel smell.

alonsito0114 · May 4, 2015

Tires 235/75/r15
And i check the engine with a scanner and give a code 41 fuel system lean fuel control?
Doest have any vaccum leaks at
all
I run the truck for 113 miles with a full tank
And the i fiill up again at it was 11 gallons
And the i divided 113%11 thats how i got 10 mpg rite
It should give me at least 18 rite the book saids highway 23 city 16 i drove it highway

alonsito0114 · May 4, 2015

And the cat converter its there but when the mecanic put the new engine he told me the last owner took all the inside of the cat like the honey cone thy have it was empty
U think thats the problem ? And the town where i live doesnt need smog

RonD · May 4, 2015

No, the Cat being there or not there won't effect MPG

Lean code is from O2 sensor data, it means computer has to run engine richer.

O2 sensor reads oxygen in the exhaust, too much oxygen means Lean burn, too little oxygen means Rich burn

Code 41 comes when computer is adding more fuel than MAF sensor data says it should be adding, so computer is letting you know that something is wrong with either the MAF data or the O2 data, it doesn't "add up", lol.

So engine is not running Lean, as code suggests, it is actually using more fuel than it should to get "normal" reading from O2 sensor.

If you have cleaned the MAF sensor and are not sure about the age of the O2 sensor then I would replace O2 sensor.

Make sure to unhook battery for 5 minutes, so computer will reboot and relearn new O2 sensor or Cleaned MAF sensor data

alonsito0114 · May 4, 2015

Yes i cleaned MAF SENSOR already is another way to test the MAF SENSOR if is bad or not ?
Or u recomend to replace the 02 sensor?
Or can i remove the 02 sensor does it need it?

RonD · May 5, 2015

This page has MAF testing info: http://www.therangerstation.com/tech_library/CleanMAF.shtml

Yes, O2 sensor is required for computer to work correctly, I would change it if you don't know if it has been changed, life of O2 is 100k miles they can/do last longer but some don't, and they do fail towards Lean so cause engine to run Rich

alonsito0114 · May 7, 2015

Does any body knows how to test the map sensor and if the ford ranger 1990 xlt 4.0 has to have a hose from the MAP SENSOR mine doesnt have it

alonsito0114 · May 11, 2015

I check my o2 sensor it works fine i test it will my truck was runing but i took it off the truck and i was dark like carbon black and also check my spark plugs and they were same color carbon black any ideas?? Plz help

alonsito0114 · May 11, 2015

Also when my truck is on throws dark carbon
Leaves a dark spot on my drive way from The the exhaust pipe

RonD · May 11, 2015

Ranger 4.0l never had MAP sensor, 1990 to 2000 the 4.0l OHV used MAF sensor

Some early models may have a Baro sensor for local air pressure, it may look like a MAP sensor, and it would have no vacuum hose attached.
This just reads sea level to 10,000ft air pressure, so computer can compensate for altitude.

I think you are thinking the system is more complicated than it is, it is way simpler than a carb setup.

MAF sensor reads the amount of air coming in.
Computer sets 14:1 air:fuel mix for that amount of air
O2 reads Oxygen in exhaust
too much Oxygen and computer adds more fuel, too little Oxygen and computer adds less fuel
Computer adjusts the mixture a few times a second, it's very fast adjustments.

If MAF data and O2 data don't add up, or make sense, then computer with set a code and turn on the CEL.

Your engine can not run blowing black smoke without the CEL being on, O2 sensor would show very little oxygen.
So either your O2 is FUBAR or your Computer is

alonsito0114 · May 11, 2015

So I went a buy a book for my truck and it shows me how to test the maf sensor so i did and works great
I test the 02 sensor as the book says and pass the test
And also i went to the savegE yard and got another maf sensor i twas good too
so do u know how to test the computer? I will pit a new 02 sensor if i have to and some times when is runing the cell comes on the later goes off so yeah may be is my computer

alonsito0114 · May 11, 2015

Every morning i let it warm up for 10 mins and leave a dark spot on my drive way but the cell doesnt come on until is runing on the road and if i shout off the cell wont come on until is runong on the road again and sometimes disapier after running more

alonsito0114 · May 18, 2015

Thanks RonD i think is fix it was my fuel regulator

ford ranger 1990 4.0l

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