'96 XLT - 5.0L 4WD

Started off with a CEL and P0401 code.

Replaced the EGR valve and a cracked air intake pipe. This particular pipe has two small tubes on the side to connect two hoses to the DPFE sensor.

Everything was working fine but I started to notice that the larger of the two hoses (connected to the "HI" port on the DPFE sensor) kept popping off. I could open the throttle in the driveway and it would pop off everytime. I installed a hose clamp to keep it connected to the DPFE sensor. That worked for about half an engine hour, then the engine just started running terrible - like it was only hitting on 5-6 cylinders. I removed the hose clamp and disconnected the hose from the DPFE sensor and within a few minutes it was running fine again. With the hose disconnected, of course the CEL came back on (P0401).

I replaced the DPFE sensor but the same thing keeps happening - the "HI" hose pops off under hard acceleration.

Other than the replacements above, the only other thing I've done is run a tank of fuel with Techron fuel treatment.

Any ideas on what could be causing this or where to go from here?

Thanks

 

Sounds like you have an exhaust restriction, causing extra-high pressure in the EGR pipe.