Cm871 help!

[TwinD]

I made the mistake of buying a demandated truck and after reading article after article on this site I am 110% sure my issues are in the the tune and hopefully that's all for now. I have a 2011 peterbilt 386 with the cm871 and she has poor fuel mileage and low boost. Fuel mileage is usually in the mid 5s and boost at max gets up to maybe 17. No boost leaks, turbo is new from a certified holset shop(purchased just before I discovered everyone's recommendation on here), and actuator went out and was replaced just one week later(last week). I have the ebay special insite on the way and will be here by Friday. Can some please help me and tell me what I'm looking for and how I can get the @m*m^2 into my truck? Also yes the cans are all completely empty, egr is still there but everything is blocked off, no lights on dash, and currently no codes, on my dash however under engine info it says "engine model 2007 isx1" which leds me to think it has a cm870 tune but i have absolutely no idea truthfully thats just my assumption. I'd greatly appreciate any and all tips, tricks, and advice

[Rawze]

The CM871 can be your best friend, or it can be your worst enemy. It is all in how its set up.. how its driven. .. and how its treated and maintained.

Having an unknown quality de-mandate/programming is NOT in its best interest.. so yeah .. copy the program out of the ecm and e-mail it to me for a proper review of what someone did in there.

here is a post related to getting this done: http://rawze.com/forums/showthread.php?t...5#pid72945


Next would be to verify 100% that all the cans under the truck are hollowed out all the way to the bare metal ... and to find out why that turbo is giving you troubles. They typically last about 600,000 miles or so unless something caused its pre-mature failure.

Low boost could be programming.. but also could be several other things too.

here is just one example ...

Is the EGR cooler still in place? .. and .. Is there a proper block plate between the exhaust manifold (near cylinder #1) and the EGR cooler on the exhaust side?. If not then this could be what is causing your turbo to get damaged/weak.

If the egr cooler is in tact, and there is no block plate ... then eventually carbon chunks will build up in the cooler, and then come spitting back out, damaging the turbine blades of the turbo and causing it to become weak, or its VG ring to hang up, etc.

Bad programming aside for a moment ... I have seen many people with de-mandated trucks go thru 4 or 5 turbos before realizing this was their problem.

There should also be a block plate installed at the intake manifold side where the egr (venturi) pipe meets it too. The egr piping running back to the egr valve and across the back of the head likes to rot out and cause low boost. This especially right at the top of the egr valve.

Give the EGR pipe that runs back to the top of egr valve a hard yank where near it meets the egr valve, and if it pops off, or is hanging loose because it rusted out right there ,.. then this could be a big issue if there any block plates missing.

[TwinD]

I can't say she's been my worst enemy yet but it's definitely far from being my best friend so I still have high hopes. The cans are completely hollow nothing in them at all, the egr cooler is gone, and the egr pipe feels solid as well. I'll make time this evening or tomorrow and take things apart to inspect the block plates and as soon as I get all my insite in and on the computer I'll send the tune over for you to review.

[Rawze]

(02-15-2024 )TwinD Wrote:  ...
the egr cooler is gone
...

Is there a coolant line going from the back of the water pump to the back of the engine block in its place?... The engine needs this whenever someone removes the egr-cooler to keep 5 and 6 cylinders properly cooled, and to prevent face-loading of the water pump due to the otherwise, blocked off circuit.

[TwinD]

There is not. This thing is definitely turning into my biggest nightmare, I'm kicking myself hard for not doing more research before buying a demandated truck.

[TwinD]

So the egr cooler was removed and was replaced with this dummy piece and it has coolant lines running into it. I was hoping I was wrong and coolant ran through there still(this is my first truck new enough to even have egr so I'm completely clueless as to how they're supposed to work). So I took the line off at the back of the water pump and it is completely dry so somehow whoever did this demandate managed to block the line from in the water pump. I don't understand at all how that would even be possible but that sure seems to be the case. It looks to me like someone did a whole hell of a lot of work to do an absolutely horrible demandate. It has block plates everywhere that I've read on here that they need to be and they're all in place and solid. Also my ebay special got delayed and is now showing it'll be here Tuesday. I guess I'll get my coolant lines figured out and ran proper then once that gets in I'll get copy of the programming sent to you and see how bad they did on the programming side. Looks like I'm apart of the bad demandate club

[Rawze]

YUP .. it sounds like it to me.

[Nilao]

I have 2 EGR coolers for a CM871 if you need 1. Neither one was leaking. One I purchased when I thought the one on my Prostar was leaking but it turned out to be a pinhole in my oil filter header plate spraying a stream of coolant up onto the EGR cooler where it ran down and dripped making me think I needed a cooler. My Prostar is down permanently so I have the new one as well as a good used one.