Follow up to my angst-filled O2 posts below.... after reading some posts here and elsewhere, I picked up a fuel pressure gage from AZ. Connected to the schrader valve and turned key to start-

13psi from the fuel pump

Started truck (03 Ex, 4.6l), pressure jumped to 53psi.

Disconnected fuel pressure regulator vac hose - 53 psi.

No vaccum gage on hand, but I could hear and feel strong vac from the regulator hose, so I am assuming it is good.

My Haynes manual says idle pressure w/vac = 30-40 psi, 40-50 psi w/out vac. I should notice a "significant" jump in psi when vac is removed. Nada.

Reved truck with accel cable, no change in fuel pressure at all. constant at 53psi.

Shut truck off. psi dropped to 43, held steady until I relieved pressure via gage.

I do not have the vacume gage to test the regulator per se. It seem fairly clear that the regulator is not working.

Could this be causing the "rich" condition seen by Bank 1 O2? Either way, it cant be good. What causes a regulator to go south?

Any thoughts or other suggestions? LIke, how do i take the regulator off? I think I see a compression ring in there. I"m guessing - relieve pressure, move stuff around, take ring off, remove old, add new, replace ring, replace vac line, retest.

Concensus?

thanks for this great forum.

 

I swear that my manual said something like 35 psi for the pressure to be considered normal. I would say if my memory is correct, then your pressure would be a good indicator of a rich condition.

As for removal and replacement, ya, you are about right. pressure relief first, then snap ring removal, install is reversal. As for the regulator going south, maybe a bad diaphragm inside.

Gotta love where Ford placed the darn thing. Right on the fuel rails right over a piping hot engine, so you will have to let it cool off first to avoid possible gas vapors in the vicinity of a hot engine valve cover. Hey, that is better than on non-returnable fuel systems, the regulator is in the tank on the fuel pump!!

Good luck!

 

I checked Haynes and those are the values they list. However, I checked the Ford OEM manual on CD (from Ebay), they list 50 psi, no values for removal of vac line. Went to double check that and couldn't find them again - that stupid "manual" is so not-user-friendly. I will have to hunt for it again to make sure.

A friend of mine who is a mechanic feels that if the regulator were bad, it would create a rich reading on both sides of the engine, and I only have it on one side. He suggests there may be a gasket leak or leak in the exhaust manifold upstream of the O2. I am going to borrow his propane test wand and hunt for intake gasket leaks. Oye. Like looking for a needle in a haystack.

 

Replace the regulator. You've verified it is defective.

It will likely also fix your rich conditions.

Your mechanic's instincts are good, however, the PCM has been trying to compensate for the over-pressure in the syupply and has had only limited success, therefore only the single rich code. If you looked at your long-term fuel trims and your freeze frame data , you will likely find that the values for both banks are skewed far to the negative side of the range and that the O2 sensors have still been reading rich exhaust mixtures.

Look at those readings before going any further with any diagnostics.

Steve

 

Ok, took another look at my manual and found that for your expedition with either the 4.6L or 5.4L, you have a range of 35 to 65 psi as a normal operating range, guess my 35 psi single value was pulled out of my **** or something. But I found something else interesting on your Expy: Apparently you only have a Mechanical Returnless Fuel System(MRFS) which is defined as:

Mechanical Returnless Fuel System (MRFS): This type of fuel delivery system does not return fuel to the fuel tank by means of a return line. Fuel pressure is controlled by a mechanical pressure regulator located on the Fuel Pump Module in the fuel tank. Vehicles equipped with MRFS do not utilize an Fuel Rail Pressure (FRP) Sensor.

If that is true, you shouldn't be able to see your fuel pressure regulator as it would be in the tank. Did your Expy have its engine replaced along with the entire fuel system? I am confused. If I am going by my service manual and comparing to what you are describing then I am afraid my info source is not helping.

There is also an Electronic Returnless Fuel System(ERFS) that is used on the 2003 Lincoln Aviator. Why on earth do car makers have to redesign something proven over and over just so they can make more variations than what is needed? This is ridiculous!! Make one proven design/concept and stick with it!

I looked further and found in the work manual section that the 2003 Expy does have a fuel regulator under the hood. This damn dvd is contradicting itself.

naw, it used to be that easy to work on these engines. now needle finding is much easier

 

Talk about confusing... the "thing" on the rail is a fuel pressure dampner - According to the manual, it smooths out the pulse (ah, that's it, a pulse dampner) from the injectors binging up and down. My DVD manual states not to confuse this with the pressure regulator. the drawing of the regulator looks very different. The manual specs say the pressure on the rail should be 50 psi, key on, engine off, and 50 psi, key on engine on. That's exactly what I got when I re-did the gage test.

My friend the mechanic took a look under the hood, and he indicated that this is the regulator. Stopped in to Ford to get a new hose for the EVAP system (hose is deteriorating, flaking off maybe related; I don't know ) and asked him to look up the regulator on his computer. He didn't show it to me, but he said, yeah, its right on the fuel rail... Ugh.

So who knows.

I used a propane wand to look for intake leaks - intake sucking up propane through a bad gasket and revving the engine. No leaks that i could see anywhere, around any hose connection downstream of the MAF.

Also got my 13 yr old son to stuff a rag in the exhaust to create back pressure to listen for an exhaust leak around the manifold to see if the manifold might be sucking in fresh air just above the O2. No such luck. I could hear exhuast hissing from around the muffler somewhere, as expected, but nothing up by the exhaust manifold. Also heard my son hissing about not being able to keep his hands on the rag! Told him I couldn't do it myself and needed his help. Suck it up son, and do it

So I picked up a vacumm gage and will check all the vac lines, but from what I can see they all have some vacuum.

Not sure what else I can check. Might have to break down and take it to F.O. R.D. double ugh.

Any other thoughts? I am getting desperate

 

I did collect the fuel trim data. I have the specs in the manual and wil check those. If I remember correctly, the short and long term trims looked fine, about +1% correction here and there. Perfect ratio would show trims at 0%

I will check carefully though. Good suggestion. Thanks.

 

Train him well and he could be your go-to garage buddy in the future!!

I believe since you are holding a constant 50 psi then that tells me there are no leaks. How old are your Heated O2 sensors? Fuel filter replacement? Maybe unplug the battery, turn the headlights on for an hour or so and make the PCM reset itself, although you mentioned that the fuel trims looked in spec. Clogged injectors maybe? clogged air filter or air horn? Gummed up throttle body? maybe time for some maintenance TLC. Otherwise with no leaks, not sure what to tell ya. Might end up being something so simple.

 

Sigh. My truck is so clean you could eat off it...

TB cleaned, using AF1 CAI - just cleaned the filter (then cleaned the maf with apprpriate cleaner), O2's were new 10k miles ago (replaced trying to fix this problem, neither new nor old O2's fixed problem concluding its not the O2's), I have an XcalII for the custom tunes and logging. Have reset the PCM numerous times with not effect. Changed back to stock and still have the bad O2 reading.

I'm beginning to think it may be electrical - wiring harness upstream of the O2 connector? The Ford guy suggested that a capacitor in the PCM may be bad, not sending enough voltage fast enough to the O2. Interesting thought but not sure how i would check that.

I guess the next thing I need to do is hook up a sacrificial O2 connector so I can reach the wiring with a meter and measure voltage in the harness and look for grounding or something.

 

Hmm.. how can you get a "rich" reading with flat trims since a skewed trims are what triggers the rich fault code(s)?

Figure THAT one out..

Steve

 

Ok, so we can rule scheduled maintenance out. I had caps go out on my Eagle Talon Tsi, which was a commonly known fact for those early DSM motor controls. I pulled its PCM and soldered new ones on the pc board. I cant remember but I thought when I was installed my SCT chip, that most if not all components under the factory gunk was surface mounted, not thru hole.

To even begin to test, you would need the entire circuit of the PCM of ONLY the portion you want to test, find the cap(s) in question and test those. There are test boxes that can measure the Farads. And by the time you did all that you could have replaced the PCM a hundred times over!! Rule absolutely anything else out that is not part of the PCM. If all else is good, sounds like a PCM replacement which mechanically is easy. And like many other electrical parts, caps can go partially bad making diagnosing them as the problem being, well, a problem. Dead caps are much easier to find and deal with.

I will say this, it might be possible that a cap did go out but yet your problem only got as bad as it did and not worse because redundant caps in the circuit at least got you running, although with a rich mixture. It might be at least worthwhile to pull the PCM and inspect the board on both sides and look for obvious component damage usually associated with a burned looking area, may be a small area but caps typically show physical signs when they go out.

HTH

 

my mechanic friend is checking at work to see if they have a test box for the 03 so we can hook up the pcm and check all the voltages. If not, then I will just make a pigtail for the bad O2 and back probe the reference voltage, ground etc.

this is simply too much fun for one person.

And meanwhile, back at the bat cave, mama's 98 E350 club wagon (yes, my other car is a 15 psgr van), has leaking rear heater lines which must be repalced, deteriorating rear AC lines, ditto, and two front calipers that need to be replaced. The van has 85K miles on it.

Gotta LUV Fords.

I will let you know about testing the pcm. I really appreciate all your inputs. Keep 'em coming if you have any other ideas, like maybe alien abduction?

 

I believe for my 03, my O2 nominal voltage is 0.45 v

Let's throw a truck party then!

Now that seems like a bunch of stuff to do on a relatively low mileage vehicle.

INDEED!!

If you see weird voltages but components otherwise seem fine, you may have lost some wiring insulation on the factory harness somewhere and it is touching ground or another voltage source. Now doesnt needle finding seem easier?

Tell the aliens not to bother unless they can fix the problem!!

 

Amen to aliens. I'm willing to give 'em a try. Couldn't do any worse.

On the pigtail, I'm looking to find the reference voltage (5v) and the ground. Make sure that there is no open ground, short etc. I can datalog the O2 switching voltage and yer right, it should vacillate around .45v.

On the van, yeah. too much work on a newish van. Bought at 48K, had $600 worth of steering work done. 2 months ago, had $#1500 of steering work done, including gear box, all ball joints. Now this stuff with the rear climate control.

I should just quit my job and become a full-time mechanic - for myself

 

Imagine asking yourself for a promotion, eh?

If I am not mistaken, and I have been alot lately, I believe O2 sensors typically range from 0 to 1 v dc. I am gonna take a guess and say that for your Expy, it is one of the two black wires as the white wires are to heat the O2. I cant believe that what I have are heated O2 sensors. Doesnt my exhaust temp get more than hot enough on its own?

Sorry to hear about the van, hope that gets better. Knock on wood, I have been very fortunate with my truck. So far trouble free, and it is quite forgiving for all the mods I have put on it, not one single CEL over 4 years and 58,000 miles.