I have read a few threads that discuss cleaning the passage in the upper intake manifold (UIM) that runs from the EGR valve to the throttle body opening.
Most people say that they remove the throttle body and clean the passage.
What tools do you use to clean this passage? I have searched many stores for a flexible wire brush to no avail.
How big, in diameter, is this passage?
Does anyone use recommend using chemicals (e.g., throttle body cleaner, electrical parts cleaner, etc.) to clean the passage?
FYI: I have a P0401 (insufficient EGR flow) that I have been trying to solve. I have already checked all of the vacuum lines, replaced the EGR valve, and replace the EVR (EGR vacuum regulator). I have not replaced the DPFE yet, but I wanted to clean the EGR passage before throwing another part at the problem.
