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Clogged DPFE signal tubes on EGR pipe

05-06-2011, 01:16 PM
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?

05-06-2011, 02:05 PM
Try bare electrical copper wire. They just might be soft enough to flex around the bend....and hard enough to push through the clog.

05-09-2011, 08:58 AM
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.

05-09-2011, 07:22 PM
Good to read that you solved the problem.

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