low boost pressure or component failure....

[Kopperhed]

'00 F250 2wd, 150k miles, starts fine, will run all day, never dies. Per my Edge Evolution gauge, max boost is 3-4 psi. I had quite a time towing a 33' 5th wheel from Anaheim to Tulsa, barely able to run 65 mph on the flats. I had no idea about the boost issue because I had the gauge monitoring trans temp, eng oil temp, ex gas temp & voltage. On the trip out, unloaded, I could cruise at 80-85 and get 20 mpg, plenty of power for that anyway, didn't suspect anything. Since temps didn't look too bad (stock coolant "gauge" in dash never even hit 1/2 way up), figured I had tackled too much trailer for a mostly stock set-up ( 4" full system MagnaFlow & K&N FIPK to go w/ the Edge Evo set to "tow").

Enuff back story.... after switching gauge display around, never hits more than 4 psi boost, ever. Pulled DTC codes: P0470, P0603, P1247. All sources concur that 1247 is low boost, only found 1 desc. for 0470- exhaust pressure sensor circuit malfunction. Does that mean a MAP sensor or something like it? Does it sound like I really am only boosting 4 psi, or a component failure giving a false indication that throws everything else off?

As stated before, can drive it all day, never dies, or runs rough........ but it makes some strange noises when the trailer is hitched up and foot is to the floor at 55 mph with the A/C on, gets a surge going like flipping a switch on and off.

Any help is appreciated.

Chris
Bixby, OK

[Kopperhed]

After more research on this site & others, I checked the rubber hose from the intake manifold (the "y" ?) to the boost sensor or MAP sensor by the A/C core. It had been previously "repaired" with a piece of a Bic pen, laying open inside some black plastic wire wrap. Replaced & now getting 11 psi boost max ....... much better, but is that all? Cleared codes before test drive, now just getting P0603.

[Kopperhed]

.............bump