I'll just be leaving mine where it is.

I don't have that kind of skill, nor do I like dealerships.

 

Dealerships are like any repair places, there are honest ones and dishonest ones, the problem is finding a good one.
My Ford dealership was going to pocket the money for the core exchange on my cylinder heads. (our companies delivery truck, not my B3000).

Personally I would trust a Canadian tire store here in Canada over a dealership, but weather or not Canadian Tire has the tools to reset the PCM is another thing.

I don't quite understand this hard reset business, didn't Ron say somewhere in another post that if you install new oxygen sensors (or any sensor) for that matter, that the PCM learns from the new parts after 3 or 4 driving cycles ???

 

Here's a video, I've come across before.
The guy in the video apparently is a Ford technician.

Resetting the PCM after Repairs are made | Ford Explorer and Ford Ranger Forums - Serious Explorations

 

Thanks, Jeff! I'll give that a look.

 

Hmm. I'll have to try that. I'll use my multimeter instead of a jumper though, monitor current flow.

Curious; I'm wanting to replace my oxygen sensors. Should I replace all three sensors or just the upstream (before catalytic) sensors?

 

I would replace all three, even though there is no code, they become less efficient as they age, I know I have to do mine.
I don't know if a multi meter would have the same effect as using a small jumper and alligator clips.
Use the multi meter at first, but the finish up with the jumper.

 

My multimeter has a current measuring function. I used it just for curiosity sake to see how much current would flow. I did let it sit for a couple of hours with just the jumper though.

I'll replace all three, then.

 

It may not cure your millage problems, but it can't hurt.
There was a time oxygen sensors were bloody expensive, but their pretty cheap now.
One of them threw up a code on mine (that was replaced), so the other two aren't far behind.

 

If I'm going through the trouble to replace two, doing the third one makes sense.

Changed out my platinum spark plugs with the new autolite 103 copper plugs, and I noticed it didn't smell quite as rich on startup.

Also, this hose coming off the manifold underneath the throttle body, driver's side of the engine coming out near the EGR. Absolutely REEKS of gasoline. It's like putting your nose in the tank. Wet with gas inside and there appears to be either black carbon buildup inside or just general grime.

 

as explained to me by dennis the mechanic

once the computer reverts to the pre programmed fuel trim , after a sensor failure ( coolant temp sensor )

the computer will not return to reading from the O2 sensors or coolant temp sensor , even though the new sensor (s) are installed '' it is the way the software is programmed "

NOT A HARD RESET !!! a deep reset is required on the newer rangers because of more data installed on the PCM.

BTW. that was 1 of the videos he warned me about

you will be taking a great chance of frying the computer by grounding out the positive and negative power cables while the computer is still connected

 

Well..... Great. Seemed to run fine, at least. Didn't throw up all over the place.

"Newer Rangers". Does my '99 fall under this? If so, I suppose the dealer wants an arm and a leg to do it, right?

 

You're not going to hurt the PCM by connecting the battery terminal cables.
It may not do a hard reset, but it's not going to damage it either.

A PCM is like any other computer, there is a BIOS chip in there (maybe more then one for back-up) that's programed at the factory like any MoBo.
Most BIOS chips can be booted into on a computer to change fan speeds, how many fans you have, setting up raid over-clocking the processor etc.
Most of these MoBo chips also have a factory reset (default setting in case one gets themselves into trouble).
An HP BIOS on a laptop is very limited, you can't do much in there except cange the boot order or clock, most desk top MoBo's have settings.

Like a PCM in a vehicle you can change when the computer stops enriching mixture at a given temperature ( as one example), in the BIOS setting..
And I am sure there are lots of things that can be changes, there may even be a default setting in there.

When someone was having problems with their laptop eg the WiFi kept cutting out even after they put in a new receiver, a hard reset has to be done to erase the "volatile" memory on the board, this drained the voltage in the capacitors so the MoBo could refer back to what the factory BIOS settings were.

The battery was removed and the power button was held down for at least 30 seconds.
No different in our trucks when it comes to the oxygen sensors and connecting the battery terminals together.
I don't think I'm wrong about this and am going to do some digging, to find some answers.
And not on the internet.

 

you may have it done free of charge

i read a news article about 2 years ago , about ford being fined by your NHTSA for failing to meet emissions standards on all of their gasoline pickup trucks

the NHTSA ordered ford to update all of the ecm / pcm computers in all of the pickup trucks dating back to 1999 i believe .

you should call a dealership to double check

mazda only charged me 89 dollars cdn . to update my ecm and pcm

 

I have never heard of NHTSA ordering Ford to update all of the ECM/PCM computers for all pickups back to 1999. I know mine has not had this done and it is ultra clean for the CA emission testing.

You may be right about that but you have also stated a combustion by-product of ethanol is oxygen. So, I question your information sources or interpretation of them because I know oxygen is not a by-product of ethanol combustion. Being a Chemist for over 40 years, I know the products of complete ethanol combustion is CO2 and H2O. Oxygen is consumed in ethanol combustion.

 

Out of boredom I decided to research the damage theory. Looked at 'bimmer' forums, chevy and gm forums, a ford forum or two, etc and I couldn't find anyone saying it would cause damage, nor any solid evidence to prove it could cause damage.

I had set my multimeter to the 'milliamps' setting to see how much current would flow, and for a split second, barely any current at all had flowed between them. I forget the exact number, but nothing to sneeze at.

My opinion: doesn't damage anything if you do it correctly.

 

The discharge would have been vey small, the capacitors involved are very tiny.

And that phot in post 109, will you take a photo from further back, it's kind of difficult to see where that is with no point of reference _ even knowing where the compressor is.

EDIT:
Never mind, I figured it out.
If that line is wet with gas, I think that's the fault.
That line goes into the EVAP purge valve, I'm surprised there isn't a code thrown up, but if the main diaphragm is leaking that bad and there is no sensor to monitor an internal leak, there won't be any code.
Assuming the diaphragm is ruptured, then the intake manifold would be sucking the gas fumes produced by the tank through the charcoal canister with no control at all from the computer.

If my diagnosis is correct the charcoal will be choked with fuel with the intake manifold constantly sucking the fuel into the EVAP system.

To see if this is the problem, remove that hose and block of the port on the manifold.
Plug the hose too and also disconnect the yellow vacuum line from the EVAP purge valve.
Remember to plug the "live" vacuum line that you just disconnected.
Don't leave the hose itself plugged off too long, you don't want allot of pressure building up in the tank from the gas fumes, just leave it plugged off long enough to see if it's the problem, but make sure that the manifold vacuum port is plugged off, having that open will cause a major vacuum leak and cause the truck to run like crap _ if at all.

This will throw an EVAP code up, but if your fuel millage increases then the EVAP system is the problem.

The only thing that doesn't make sense if that's where all the gas going, one would think that the plugs would black and sooty, but then again maybe not.
The excess fuel isn't actually being added through the injectors, but being pulled into the engine as gas vapour in excessive amounts through that port on the manifold.
The faster you go, the more vacuum is created (up to the max atmospheric pressure) and the more fuel is being sucked into the engine.
Slow speeds would less vacuum and the affect wouldn't be as prevalent.
Because the vacuum never remains constant under different driving conditions the gas is never being sucked in there at a constant rate _ this would explain why the plugs are not black.

Just a theory...
But easy to test if you do the above.

 

Right now I've got a clear line going from the manifold to the black hose. I'm going to drive it a little bit first and see what builds up inside the clear vinyl hose.

I'm going to do a bit of research on this system and see what all I can find. This would certainly explain why my truck smells rich, why the plugs aren't sooty, and why my mileage sucks lemons.

Also, I have a new coolant temp sensor headed this way. for 7 bucks I figured it couldn't hurt to toss a new one at it, given I don't believe it's accurate.

 

Why even bother with all that.
Just disconnect the EVAP system, do another millage test and see if there is improvement.

 

I plan on doing that as well.

I went out to the garage and pulled the device off of it's mount and did some inspection. I noticed right away it was covered with black crud, although it didn't smell like much of anything.

Checked the plug, and it's receiving battery voltage with the key on, zip with the key off. On the bench, I attempted to pull a vacuum via the small yellow hose and noted that I could not pull a vacuum under any circumstance. I could also not pull air through the two larger hoses either.

 

It sounds like it's OK, mine reacts the same way.
The engines vacuum is in the "always-on" position _ the solenoid doesn't turn it off, but rather diverts it to the large diaphragm for it to vent the gas fumes.
The PCM controls the vacuum to the unit through that solenoid motor that you tested the voltage on.
The solenoid opens the vacuum and some of it is diverted to the large diaphragm venting the fumes from the charcoal canister into the intake manifold through the larger hose connections on the device.

This is the way I believe it works, I couldn't find any exact info on how it actually works.
I also tested the same unit on another truck that someone I knew, and it acted the same way.

Even though the unit appears to be operating correctly, the excess small and wet gas in the manifold hose isn't normal and I'm still going to maintain that there is something wrong with the EVAP system.

Here is my vacuum diaphragm, yours should be the same.
https://www.ranger-forums.com/2-9l-3...7/#post2107388

The only other electrical device in the system is "Vent Solenoid Valve" at the rear underneath the box.
Check to see if yours is rusty, but again, any fault in the system would bring up a code _ one would think.

 

Well, with the evap system disconnected, I'll see how it runs tomorrow when I deliver a package. If it throws any codes at me, I'll post them.

 

With it disconnected, it will throw a code, but at this point that doesn't matter.
All I want to find out (what you want to find out) is if the EVAP system is the fault of the bad fuel economy.
By disconnecting it, you will find that out, the engine will run normally with out it as long as that manifold vacuum port is plugged off.

 

Both sides are plugged off. the yellow vacuum line on both ends, and the larger hose on both ends. Used some clear tubing I had in place of the factory hose with some 1/2 inch bolts stuffed in them so I wouldn't ruin the black hose by stretching it.

 

Just ran around with the evap system disconnected. Oddly enough, even after probably 20 minutes of driving with two restarts, it didn't throw a check engine light. It, at first glance, seemed to not care at all, as if I didn't disconnect it.

 

It can take a few days, and yes, the truck will run happily with it disconnected.
The EVAP system doesn't directly affect the proper running of the truck, not like faulty plugs or bad wires etc.
All it does is manage the fumes from the fuel tank and those fumes are simply pulled into the engine through that port on the intake manifold.
There's no sensor involved in that area, so there's nothing for the PCM to adjust or throw up a specific code.


You should eventually get a code that you have a blocked vacuum line.
And there may be others.