Jim Culver
12-03-2005, 10:32 PM
About 3 months ago (warmer weather) I bought a 2001 F-350 Crew Cab LB 7.3 Auto 4x4. From my experience with my '85 ATS turbo 6.9, I had the 7.3 muffler removed making it straight 3" exhaust. Other than a K&N type (panel) intake filter it's stock.
Since the cooler weather has begun (KS) after the engine has started just fine (idling) you begin to hear the waste gate opening and closing sounding like a 'blow torch' (not cool for the neighbors @ 6 AM). Once I touched the accelerator it was fine for a little bit, then the cycle would start again. Once driven it was fine.
Now with the OAT in the 20 degree range it does the above plus the engine & truck surges (approx 200 RPM). Not good.
A chat with a local dealer mechanic suggested I might want to replace the Exhaust Back Pressure sensor (4C3Z-9J460-A, retail $138.00), I bought one but decide to write you guys before I swapped them out. The mech explained this sensor reads the pressure between the engine and the turbo, and didn't really think the muff removal was a big factor. He also said he did some other work on a truck that did the cycling but didn't surge and the customer didn't complain about it (it's muff was removed). A buddy who had a '99 that he had removed the muff on cycled like this.
Help, my fellow 7.3 brothers. Not gonna do this much longer.
Since the cooler weather has begun (KS) after the engine has started just fine (idling) you begin to hear the waste gate opening and closing sounding like a 'blow torch' (not cool for the neighbors @ 6 AM). Once I touched the accelerator it was fine for a little bit, then the cycle would start again. Once driven it was fine.
Now with the OAT in the 20 degree range it does the above plus the engine & truck surges (approx 200 RPM). Not good.
A chat with a local dealer mechanic suggested I might want to replace the Exhaust Back Pressure sensor (4C3Z-9J460-A, retail $138.00), I bought one but decide to write you guys before I swapped them out. The mech explained this sensor reads the pressure between the engine and the turbo, and didn't really think the muff removal was a big factor. He also said he did some other work on a truck that did the cycling but didn't surge and the customer didn't complain about it (it's muff was removed). A buddy who had a '99 that he had removed the muff on cycled like this.
Help, my fellow 7.3 brothers. Not gonna do this much longer.