Clogged DPFE signal tubes on EGR pipe

[tomj76]

The two signal tubes, located on the EGR pipe at the back of the engine are clogged on my '96, 3.8l. It appears to be clogged with carbon.

I first discovered this while diagnosiing the cause of P0401 from the PCM. I checked that the EGR valve operates and the EGR tube and orphice is clear enough allow flow that will stall the engine at idle. The DPFE operates, as I can apply pressure to one port and demostrate a voltage change on the signal wire. However, no exhaust pressure is evident at the outlet of each of these tubes. In addition, I can't blow any air through them, either by mouth or by compressed air. They are completed blocked.

I used a small drill bit to remove part of the clog, but since the tubes are curved I can't remove the entire blockage. I tried a small piece of music wire, but the material is hard enough that the progress was slow.

Are there any suggestions of cleaning approaches that will be effective in this situation?

[Off_Timing]

Try bare electrical copper wire. They just might be soft enough to flex around the bend....and hard enough to push through the clog.

[tomj76]

I used tried soaking it in some B-12, but that alone didn't work. Then I tried a piece of music wire as a drill, which worked to some degree. Finally, I heated the pipe until glowing red to burn out the carbon and then followed up with the music wire to clear them out.

The EGR codes are now gone.

[wiswind]

Good to read that you solved the problem.