cm 871 regen fail

[Rawze]

Watch my video on how a healthy CM871 regen process works. Take note of the time it takes for it to get up to temp... how high the temps go etc.

You mentioned that it only got to 700 gecrees or so.. this is too low and will cause the process to fail, or run endlessly. it should have quickly gotten to 900+.

Some thigs to also verify...

ENSURE the exact program in installed into the ECM for that model engine and truck. - Often, people will "uprate" the power by using a different program for the engine/truck and those emissions systems will act up and not function correctly.

The RPM readings for the turbo .... Depends on what model turbocharger and tier engine it has. you did not mention this. - a small tier engine will have higher positioning on the turbo during a regen cycle than what you mentioned and will have higher rpm readings. - A big-tier engine (500+HP, larger injectors, bigger impeller holset) will have the lower 85-89% range positioning and the much lower rpm on the turbo that you are seeing. -- Again, right back to ensuring the 100% correct program for the particular truck and engine is in the ecm.

Like others have said, REPLACE the imap and exhaust gas pressure senors if they are more thana year old. Do not rely on them, and they cannot be cleaned properly without them reading incorrectly after.

i talk about some of this stuff in this video. Here is how a healthy one should act...



take the time to watch through it as I talk about time it takes to get up to temp, etc. and a lot of other stuff.

And then there is the fact that no one has likely doen a thourough egr tune-up on it, cleaned out the egr valve, possibly the egr cooler removed and cleaned out or replaced if it is the origional (or at least 5+ years old) and it has been all these yaears later, etc. etc.
and it is no longer doing its job to keep exhaust empts down properly or is packed up and restrictive.

For the fuel to ignite properly and get that DPf quickly to 900+ degrees on its face, it needs to be spraying very well out of the doser injector. Cleaning that injector is a novel idea, but if it can;t regen properly and temps are the issue, the next step is to simply replace that doser, especially if it is old, has a lot of miles on it, like has been mentioned.

Exhaust/intake/egr piping leaks can caue it too. EGR piping boots across the back of the engine are notorious for developing a hole in them where you cannot see it. Plus the egr hard-pipe that leads away from the intake manifold, down to the top of the egr valve likes to rot out right at the top of the egr valve and leak like mad there, or pop loose form its welds. Give it a medium-hard yank and see if it has popped loose at the egr valve joint.

It is heavily recommended to make and insteall blocking plates at the intake of the turbo, and turbo outlet, and pressurize the entire engine up to 30 psi or so to find all the places that are causing boost, egr, and exhaust leaks. - It is amazing the places they can leak, like compressor pushing air into the crank case, egr piping elbow connections that have failed, and all sorts of places besides just the CAC.