pull off the oil fill cap , start engine , place hand over oil fill hole and feel for engine blow by

if you feel a lot of air being blown out , then you have a serious worn engine

i still say it is the computer not reading the coolant temperature correctly

 

No, none of these, if the fuel pump was out-putting to much pressure to make it run at 10mpg, then the plugs would be black and sooty, and so would the exhaust as Ron pointed out.

I don't think his engine is worn out to the point where he's only getting 10mpg.
A worn engine with that much blow-by that would only allow 10mpg would be excessive.
There would be an oily mess inside the throttle tube where the vent is off the oil filler cap.
Also on the other valve cover where the PCV valve is.

There is a possibility that the engine isn't getting up to temperature, but as Ron pointed out, if it's only getting 10mpg, the plugs would be black and sooty _ as would be the exhaust.

@ ArcticWolf

I think the fuel test has to be repeated and here's what we did in this car club I used to belong to on our fuel economy runs.
Fill up with fuel to the neck of the filler tube to the point where you can see the gas and note as best you can where that level is.
Write down the reading on the odometer (I don't think our trucks have a trip odometer)
Take it on that same drive where you only got 10mpg (or anywhere, it doesn't matter).
Now go back to that same spot where you first filled up. If your truck was sitting on level ground the first time, try to find a spot where the ground was just as level.
Now this is important, fill up to exactly where you did the first time around, or as close as humanly possible.
Write down how many gallons and from your odometer reading you can simply calculate how many mpg you're getting.

Obviously tire size, pressure, and odometer accuracy will have an affect on the outcome, but I don't think those things are "out" so much that it would only show 10mpg.

Filling up to the neck is also a good "leak" test for that system too.

 

Wouldn't filling the tank that full damage the EVAP system?

Although that does bring to mind, could my cap's seal be part of it?

@david: I do plan on replacing the sensor here within the next week, as I don't believe it's accurate anymore. So, that can be crossed off the list here somewhat soon.

 

At this point, only Ron can answer that question if it will damage the EVAP system, but I don't see how.
It will certainly show up any leaks in it though, but remember, if there were any leaks, you would get a CEL.
If your cap seal was a part of it and the excess gas was simply evaporating out a bad seal, a CEL would come on for the EVAP system.
It would be a very big leak indeed to leak out that much fuel, you would smell EXCESSIVE fuel odors.
That much gas leaking out of the system would be seen and smelled.
That's why I think you should do your fuel economy test again.

 

no! the engine oil fill cap does not have a sensor

( the oil fill cap on the engine`s valve cover )

you are pulling the cap off and putting your hand over the hole to feel for cylinder compression blow by with the engine running

 

take some time to read this blog

it seems that some vehicle owners in the southern states are experiencing serious mechanical problems or even catastrophic engine failures .

due to the hot moisture laden air

Fuel School: Phase Separation in Ethanol Blended Gasoline

 

That's possible, I suppose; however, why would my father's 03 edge 2wd be getting 350 miles out of a tank? He, too, burns 87 and lives in the same city I do. His is also a flexfuel 3.0.

After doing some research to read some numbers, it looks to me like the ECU is fighting itself. The o2 sensors seem to favor telling the ECU to add fuel, but the longterm fuel trim numbers mostly stay negative, as if the engine is continually trying to remove fuel.

 

did you at any point in the past months take your truck to the dealership for any type of service

ford was ordered by the u.s government to update the ecm / pcm software on all of their built trucks dating back to 1999 , at no cost to the vehicle owner ( due to emissions non compliance )

if you did , then they may uploaded the wrong software to your pcm

 

I've never taken my ranger to the dealership. The closest it's been to their bays is when I pass through the used lot when I'm bored.

 

For cheese_man, Ford mechanic would set the "choke off" for 78C, which is 170F
Yes the EEC-V computers(1996 and up) are easily programmable if you have the software.



The spark plugs don't show signs of running Rich so choke mode is off and computer is running the engine for best fuel economy, regardless of what temp says.

So not a computer or sensor issue or you would see signs of it on the spark plug tips, no way around that, they are inside each cylinder, so they "show" if engine is running lean, rich, or just right, very light brown is just right.

Lower compression would show as a lack of power, especially when climbing even a small hill, it would feel like you were pulling a trailer.


Most engines stall now when you pull off oil filler cap while they are running, but depends on PCV system, better to pull dipstick, should be a slight, very slight, negative pressure there.


On some models the EVAP canister is back by the gas tank, if you overfill the tank the gas will go into the canister and ruin the charcoal filter, can be an expensive repair.
So best to stop filling at first "click", second "click" for sure.
If you fill it up the filler neck too far the gas can get into the EVAP hoses at the top of the gas tank which over time can cause them to clog up as residue builds up in the low spots of the hoses, another expensive time consuming repair

 

According to my eyes, the plugs look snow white.

I've noticed my truck is loving to contradict itself as of late. It's exhaust smell says rich, it's plugs say just right, no codes are thrown, and in my opinion, it looks like the computer is fighting itself. Would it be a wise idea to replace the upstream 02 sensors? I'm considering doing so. From what I've read, many people report a decline in fuel economy right about my mileage and supposedly swapping the sensors restores their mileage.

 

Your father's truck is a 2WD with spindles in the front and he also has the 2002 + 3.0 with the composite upper intake set up and that makes a big difference.
I'm also thinking that your fuel tank isn't a 20 gallon tank. Most of the gas tanks I've seen in the Rangers would only hold 16.4 gallons of gas.

 

NO RON!! the mechanic made it clear to me

He set the choke off point to 78 degrees fahrenheit not celcius

i have removed my oil fill cap several times with the engine running , the engine never stalled any one of those times

this is why i so hate computer controlled vehicles

carbeurated vehicles are so much easier to figure out running problems

 

Upstream O2 sensors last about 100-150k miles
Downstream O2 sees cleaner exhaust so lasts at least twice as long if not more.

As the chemical in an O2 sensor is used up they tend to show the computer a high oxygen content for exhaust, Lean, so computer will run the engine Richer than it needs to be run.
But not 10MPG Richer, lol.
So yes, changing older(100k+) upstream O2 sensors will improve MPG on any vehicle.



Liquid gasoline won't ignite with a spark, gasoline needs to be in a vapor state for a spark to work.
Gasoline vaporizes/evaporates fairly well even at room temps, 70+ degF, this is why it feels cold if you spill some gas on your skin, it is evaporating from body heat.

And that's why a gasoline engine needs at least 120psi compression, to heat up the gas and get it to vaporize completely and warm enough for a spark to ignite it.

The rate at which gasoline(or any other liquid) can evaporate at any temperature is based on the exposed surface area of the gasoline.
One large drop of gasoline will evaporate slower than many smaller drops at any temperature.

In a carburetor the air flow passing the Jets would suck gas out and into the intake, so Jets have 0psi pushing gas out, only suction pulled gas out, and while the drops of gas are small they are not that small, lol.
So not alot of evaporation/vaporization taking place at room temps, as engine/intake got warmer evaporation got better.
This is why most engines still use pre-warmed air on cold start, air is pulled from around exhaust manifold after startup, this helps to increase intake air temps to evaporate gasoline better.

Not sure on exact numbers so just an example here:
Lets say at 70degF 20% of the gasoline coming out of the Jets was a vapor when it reached the intake valves.
And a cold gasoline engine needs 60% vapor to start.
The Choke Plate was needed to increase the vacuum at the Jets to suck in 3 times more gasoline than normally needed, to get at least 60% vapor in each cylinder for starting.

The engine is running Richer by definition since it is consuming more gas but that gas isn't being used specifically to power the engine, just to get enough vapor to keep engine running until it warms up enough for gasoline to vaporized better in the intake.
And the higher idle is to keep the % up.
Engine still needs the same 14.7:1 air:fuel ratio to run, just needs more gas to get that ratio when engine is cold.

Fuel injection sprays the gasoline out under pressure so much smaller drops with more surface area to allow faster vaporization/evaporation, and since injectors are just outside the intake valve, there is less cold metal contact to change the vapor back to liquid.
But............cold engine still needs that 60% vapor to start.

Outside temp dictates engines cold start temp, the lower the temp the less vaporization there will be even with fuel injection, as that is a property of the gasoline not the engine system.

Not sure why any one would use 78degF, lowest I would go would be 100degF.
And the "Choke off" temp is only one part of the computers calculations for air:fuel mix.
IAT(intake air temp) sensor would still keep extra fuel coming in as that is an air density calculation, colder air is heavier and causes less evaporation so requires more gasoline.

Yes, my 4.0l OHV won't stall with oil filler removed, but many other newer vehicle I have worked on will.
Dip stick tube is still best method to test for blow-by, worn rings.

 

dennis is the mazda mechanic

he owned a b4000 for 7 years , he played with various CHOKE OFF settings during bone chilling cold temperatures to ensure maximum fuel economy during those temperatures

he stated that once the engine starts , and the engine coolant reaches 78 degrees the CHOKE is not required after that

as the engine is running and will continue to run

after he updated my pcm , he had to go into the soft ware and change some settings back including the CHOKE OFF settings

after the CHOKE OFF is enabled , he set the software to start reading from the oxygen sensors

i willl see if those settings work ( dare i say )when winter arrives

we had a 15 minute discussion

 

Today while I was messing with my new center console, getting it wired in and all that, I decided to wipe my fingers on the inside of the tailpipe. Black and sooty.

I also used my scan software on my father's 03, 3.0 edge 2wd while he drove, and I found the behavior to be somewhat different from mine. While mine seemed to be fighting itself, his did not. I also noticed that it would not come out of 'closed loop' unless heavy deceleration was detected, even on the highway. Once mine is put back together, I'll run the same test again now that I have my electric fan installed.

 

Your father's truck is a 2WD with spindles in the front and he also has the 2002 + 3.0 with the composite upper intake set up and that makes a big difference.
I'm also thinking that your fuel tank isn't a 20 gallon tank. Most of the gas tanks I've seen in the Rangers would only hold 16.4 gallons of gas.

 

Did see anything mentioned but are you able to use GPS to determine actual mileage gone (entire tank) fill up then divide the number to see actual MPG. If this was done, apologies for bringing it up again but I wasn't sure if the 10mpg was estimated off the speedo rather than using GPS.

-Nigel

 

Unfortunately I don't own a GPS capable of calculating MPG for me. The most I have to go on is the trip odometer.

 

Did another run today. It runs closed loop 99.99% of the time. I noticed that the sensor on bank two takes a while now to start sending something, and it's very lazy, too. Bank 1 sensor is still rapidly responding.

 

did you replace the coolant temperature sensor / sender

it will not return to open loop until the computer is reset

 

I'm going to place an order for the sensor tomorrow.

Correct me if I'm wrong, but closed loop means that it's reading from the oxygen sensors. Open loop means it's running a preset of sorts. Isn't closed loop ideally what we want?

Tomorrow I'm also going to install my copper spark plugs after I get some more antiseize. The new wires are already installed. Runs a bit better now.

 

the computer is not running closed loop even though it looks like it .

the computer needs the proper engine coolant temperature to switch to closed loop

dennis told me that the software will only switch to closed loop just before the engine reaches normal operating temperature .

that is why he set mine for " CHOKE OFF SETTING " to 78 degrees . to attain and maintain maximum fuel economy

 

Makes sense. When it was stone cold and I pulled out, it was reading 'closed loop'.

I'm assuming a guy would need to take his Ranger to the (shudders) dealership for that setting to be changed?

 

during our 15 minute discussion

dennis warned me about youtube videos showing you how to reset engine computers

his words were!!! those people really want to pay for a new engine computer don`t they

only the dealership has the proper computer and software to deeply reset engine computers