Cummins & Carbon

[Keith Browning]

No different than the Ford engines. EGR engines all have similar problems with carbon build up, sticking EGR valves, loose carbon breaking off, plugged passages and fouled sensors. These pictures are from a 2003 F750 NJNG truck that has low miles but a LOT of idle hours. Complaints were lack of power and rough idle at times  especially after decel coming to a stop. It had two codes for intake manifold pressure one being a pressure sensor circuit code. Funny thing about Cummins codes is that circuit codes are often "conditional" codes. If the circuit codes are not "Active" it is recommended to go after the boost related codes. Of course if you are a Cummins tech using QSOL and EDS (Expert Diagnostic System) you will be running all codes through the code analyzer and proceeding from there. 

 

The intake air heater grid was 75% restricted with carbon - a LOT of free chunks of broken up carbon. I did not

remove the intake to clean the grid. I simply used my shop vac, a pick and a brush.

 

 

The EGR valve nicely crusted up and sticking a little. They disassemble for cleaning and Cummins has a nice

cleaning solution that eats through the carbon - flushes out with water. Dodge has the same cleaner available.

 

The passages in the EGR adapter block were heavily restricted as well. I assume that the free chunks of carbon

on the intake heater grid came from here. Used the cleaning solution on this as well.

 

And of course the intake manifold temp/pressure sensor was fouled up too.  It got replaced.