CM871 code 2973

[Rawze]

(02-25-2020 )Valley11 Wrote:  I loaded the file that Rawze so nicely updated and fixed up for me. As soon as I started the truck it was noticeable that there were changes made. At low idle 750rpm the truck idles smooth Turbo 54% closed compared to 72% closed. Test driving around the truck seems to run nice Intake manifold and exhaust gas pressures are both lower then compaired to before. Had about 34psi boost trying to load engine up a hill on test drive. The real test will be once I get it out with a load again. I pressure tested the intake system starting at the CAC did not have the correct fittings to start at turbo, tightened couple turbo boot clamps but didn't find any big leaks. Very interested to see if my poor MPG improves 2mpg before.

34 is a touch low, but it should not hurt anything for that power/torque. That can very easily be adjusted up to a more normal 36-37 if necessary and it has been confirmed that nothing else is wrong.


if you say you were getting 2 mpg ... something is still likely very wrong. Even heavy haul trucks, and trucks with pretty bad programming get higher mpg than that if the engine and exhaust is healthy.

Also might want to disconnect the exhaust piping at one of the joints between the turbo and inlet of the DOC element temporarily, test drive it and see if the boost improves / goes up. -- if so, then you have an exhaust restriction somewhere that needs to be corrected.