(This is not a fuel mileage rant - I'm trying to diagnose what I think is a problem with mine)

Scenario:
My '05 F250 SD with the new 3v V10 (3,500 miles) is running way rich. The chrome tailpipe is covered in black all around the outside. I clean it and it takes about 50 miles for it to be covered again.
The truck gets 10-11mpg highway at best empty, and 5-6mpg at best towing my 5th wheel - level highway at 55-60mph. It doesn't feel like it's laboring at all, and I'm not on the gas much either. If I do (get on the gas), or climb any hills, etc, it goes down to 4-5mpg.

There are no DTCs and no CEL. The dealer tried the lastest software update form Ford - no change. They are now washing their hands of it.

It seems strange because my last v10 was nowhere near this bad.

Does anyone have any experience with these symptoms? The local speed shop guru is going to start a full diagnostics this week with his latest Snap-On stuff, to see what we can find.

Thanks - Norm

 

Using an OBDII scanner, check the MAF flow and see if it makes sense. Also, of course, check the injector duty cycle/fuel-trim, and whatever else you can check, and see if it makes sense...

Who knows, maybe the MAF was manufactured wrong and it's reading higher air flow than "real"...

One thing - do you think it would pass emissions? If not, Ford HAS TO FIX IT... a failed emissions slip is not something they can say is "normal".

art k.

 

along with what Art said chk the fuel pressure at the fuel rail.If the fuel regulator is not controling the pressure between 35-39 psi the regulator is bad.High fuel pressure will cause a rich condition.
Oh wait this is an 05 ,does anyone know the pressure on an 05 ,has it changed?
Are you running 87 octane in the truck?

Rich

 

Thanks for the data.

In closed loop, I believe that the ECM should trim any MAF, injector pulse or fuel pressure irregularities (via the upstream O2). Things we will be diagnosing:

- Upstream O2 readings vs. actual fuel/air (stable load, part load). Since my problems are during closed loop conditions, this should be a significant indicator.
- Fuel injector pulse width modulation at part throttle (had this problem on another "modified" MAP-based motor, so I figured I'd try this anyway).

These will determine the next set of steps.

I've tried 91 and 89 octane tests (no 87), with no changes in mileage or "butt" feel.

Krewat,
Good point. I am thinking of using the "emissions" route with Ford - just need some "convincing" data to get the dealer to go to the next level.

Thanks - Norm

 

VT,so you are running only 91 or 89 in the truck? if I miss understood your post disregard mine below and continue your investigation
Rich
also what is the elevation your at above sea level?

if so ,you may be using the dirty tailpipe as a bad indicator of running rich.
these vehicle are designed to run on 87 anything above that is really causing unburned fuel to exit the tailpipe.
I believe the fuel mapping in the pcm isn't capable of going less than 14.1 to 1 air fuel ratio in closed loop (stoich )
Once the pcm achieves this it won't lean out any more thus you will get a black sooty tail pipe.
Now this is all based on 02 spec's because this is what I have at my disposal.
If they have changed parameters its possible.
Keep us informed
Rich

 

Im not sure on the V10 but in the past i have seen a few 4.0 sohc run super rich and have mileage go down the tube because the thermostat wasn't opening properly allowing temp to rise enough for the pcm to add fuel to try to cool down cylinders.. probably a long shot at 3500 miles but thought id throw it out there

 

is it driven in a lot of short trip cold weather driving? short trip aand cold wether means it would not enter open loop.

 

VintageTin

go to:

www.motorcraftservice.com/vdirs/retail/default.asp?pageid=diag_theory_retail&gutsid=diags heet&menuIndex1=40

Link to the 2005 OBDII PDF and read the entire thing for some clues to the emissions ares and the truth table and driving cycles to set conditions and perform proper controls.

My guy says that the throttle transducer for the foot feed or the TPS may be out of whack much like CaptChas had when his was new.... his was running too lean if I recall but these areas could impact either way if I am reading the OBDII correctly.

Very unlikely the fuel pressure is set too high...read the section on the new return-less logic

could be as simple as CHT switch stuck low...

In either case Ford has to help because what you are describing sounds to me like the catalytic converter may be polluted and at least you should get a new very expensive cat out of the deal.

I am very leery of techs who first think to re-flash a computer.....not wise in my experience

My tail pipe is light black, sort of rich, not the lean tan/ semi white I am used to when I tune my carbed motors. All the gas V10s I have looked at including my small fleet SuperDuty and a few of the 5.4s in the company lot are mostly light to dark black and not sooty. I rarely smell raw fuel except right after cold start from cool to cold long overnight sit.

 

I have been doing a lot of short trips lately and the tailpipe is fairly dark. If I wipe my finger on the bottom and the sides, nothing sticks to my finger, If I wipe the top of the pipe a little soot sticks to my finger.

As Ford390 says, I am not too worried about this. She runs great and fuel economy is still improving slightly so I think this is normal for this engine. Wife's Honda and both kid's Corollas stay clean and no soot will ever stick to your fingers but a 4 cylinder
car is a different animal for sure.

 

The Microsoft way of fixing things has permeated the general culture of computer users.

Got a problem with Windows? Reboot. Did it fix it? Yes. Well, then leave us alone. If that doesn't fix it, update everything. Still didn't fix it? Well, it must be your fault.

Do you realize how MANY production Windows boxes out there are rebooted every weekend to clear up memory leaks and other problems? I know of more than 5 different Fortune 100 companies that all their Windows servers have scheduled reboots at least once a week.

I can't wait for Microsoft to get into our vehicles - we'll be disconnecting the battery every weekend

art k.

 

After reading some more about this new fly by wire throttle control.
ETC as they call it.I'll go along with what fredvon has said.
Something is not calibrated right.
In most of the tables the time to post a DTC range from instant to 30 secs
Why no codes?.

But running higher octane fuel will show as a black pipe and a waisted $

Art thats the new way reboot it that will fix it! If not at least we get paid warranty $ New techs LOL!

Rich

 

I haven't been following this closely enough to remember, but remember: Just because the check-engine light isn't on doesn't mean there's no DTC's (codes).

I can get a "primary fuel pump circuit low" code without lighting the light, and if that ain't something seriously wrong, I don't know what is

 

art were you talking to me ?
Take a look at the way they do redundant test within the newer system (OBDII/can)
I have to believe its because some of these sensors are flakey and change range so quickly the pcm retest the parameters sees it okay on the next test,so no code.

Rich

 

I don't remember anymore!

Ahhg!

I'll shut up now

 

Me too !
Its raining here so hard ,I'll problably have misfires in the am!!!!!!!! LOL!
Rich