A friend on mine purchased a 08' E-450 motorhome, and then passed away. His wife asked me to take a look at it because it was running rough.
What I found was that both banks had lean alarms, and yes, it ran real rough. In the last 9 months, it's probably had about 100 miles put on it. BTW, it only has 16,000 miles total on it.

I inspected the vacuum hoses, and found no obvious leaks. It's a 3 valve engine, so your read the fuel pressure on the OBD2 port----65psi. The oxygen sensors read about .03-.05V, but when I put some propane in the air intake to richen it up both jumped up to about .8 volts. The MAF sensor looks perfectly clean, and with the Key on engine off, it reads .000. At a hot idle it reads about 9.00. On both banks, the long and short fuel trim reads zero. I put in 20 gallons of non-ethanol gas and after a 30 mile ride it didn't change anything. However, when I floored it, it seemed to run OK, but when I let off, both 02 sensors jumped up to .8 volts, and then down to .03. Then the short term fuel trims jumped up to positive 32 for a short time and then went back to zero. Even as lousy as it idles, the engine vacuum is a little over 15 in/hg via the OBD2 port.

Any help would be appreciated because except for the lean condition, I don't see anything wrong.

Frank

 

I began to wonder if it has some water in the gas tank. I talked to the lady that owns it, and she said that she thought her husband had put in non-ethanol gas in it the last time he fueled it up. As I said above, I put in another 20 gallons of non-ethanol gas in it. Non ethanol fuel doesn't absorb much water. I started to pull the fuel filter to see if it had water in it, so I ran the left side up on blocks of wood to get more room underneath it. It seemed to me that it ran better that way, reasoned that there was water in the tank and tilting it caused the water to flow to the lowest point, or the right side of the tank. I seem to have lost my fuel filter connector release tool, so I took it up and filled it up with 10% ethanol fuel (another 22 gallons). I took it for a ride on a 55 mph road, and after flooring it a couple of times, it bank 1 O2 sensor started to indicate a proper mixture at a 55 MPH cruise. The other bank never quite got there. I came to a redlight, and after I started driving again, it stayed lean unless I floored it for a bit. It's still running terrible. I'll let it cool down and then I'll check thoroughly for vacuum leaks again.

 

I think I may have found the problem, or at least one of them. My Actron 9180 reads out pressures in KPA, so I didn't immediately realize that the reading I was getting for barometric pressure (72KPA) was only 21" of mercury. Our elevation here is about 1100' and the ECM was being told that it was way up in the mountains, so it makes the mixture real lean.

Does anybody have any idea where the BAP (Barometric Absolute Pressure) sensor is located on Econolines? Also, how about Freestars? If my Freestar happens to use the same sensor I could try the Freestar's in the Econoline to see how it'll run with the proper signal.

 

I've got a picture that shows where the barometric sensor is supposed to be located....under the steering column on the left side, but it's not detailed enough to tell where it's at close enough to find it. Please help me to find it.

 

I just received the Ford Service manuals for the E series, and it shows that the only engine that has a barometric pressure sensor is the diesel engine. My Actron scanner shows the barometric pressure, so something is telling the PCM what the pressure is. Same with my 06 Freestar---it also shows the barometric pressure but there is no listing for an external barometric pressure sensor. A friend on another site found

Ford Workshop Manuals > E 450 V10-6.8L (2008) > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and Switches - Computers and Control Systems > Barometric Pressure Sensor > Component Information > Locations

which indicates that the 6.8L does indeed have a barometric pressure sensor. I wonder if....

1)There are 2 different emission systems on these vans,

2)Is there a chance that the barometric pressure sensors in this E-450 and also my Freestar are actually in the PCM.

Anybody have any idea on who I could contact in order to find out more information on this? Any other internet sites that I can look for help on?

 

It's fixed!!!!! I stumbled on a video on YouTube that talked about the MAF being dirty and causing the engine to run real lean and also to give you the reading of lower barometric pressure. I'd already looked at the MAF and it appeared to be clean (only 16,000 miles on clock) Hmmm. That meant that the barometric pressure was a calculated number, not from a sensor. I cleaned the MAF and when I started it it was a different sounding engine and the O2 sensors were both in range. I took it for a ride and the indicated barometric pressure reading went from .72 up to .95. I think it's still a little lower than it should be, but it's in closed loop and running good.