CM871 poor power and fuel econ
04-09-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #28
RE: CM871 poor power and fuel econ
I did the leak down test and replaced the injectors. #4 was obviously bad. Blew multiple bubbles every revolution and less resistance against the handle when turning it through. #1 only blew a small bubble, but did it every revolution. But I have not retested it since putting it back together so I will do that again. The only thing that changed, apart from taking the overhead apart and putting it back together, was the injectors. And after I fired it back up, it would shut down correctly and has since. So maybe a slightly bad actuator and bad injector combo caused the run on???

The reasons we ran the cutout test are low power, rough running, and a white haze at idle and puffs white smoke if you tap the throttle while idling. No oil usage and no water loss. The mechanic did the cutout test while I was watching and talking with him. Rear bank ran good and exhaust cleaned up. Front bank ran rough and the haze was present. Both fueling actuators had the tops popped off while driving and we replaced the timing actuators for excessive side play. All had some debris in them but not much. All looked to be original equipment with 925k miles.
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04-09-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #29
RE: CM871 poor power and fuel econ
(04-09-2022 )Grounded Pilot Wrote:  I did the leak down test and replaced the injectors. #4 was obviously bad. Blew multiple bubbles every revolution and less resistance against the handle when turning it through. #1 only blew a small bubble, but did it every revolution. But I have not retested it since putting it back together so I will do that again. The only thing that changed, apart from taking the overhead apart and putting it back together, was the injectors. And after I fired it back up, it would shut down correctly and has since. So maybe a slightly bad actuator and bad injector combo caused the run on???

The reasons we ran the cutout test are low power, rough running, and a white haze at idle and puffs white smoke if you tap the throttle while idling. No oil usage and no water loss. The mechanic did the cutout test while I was watching and talking with him. Rear bank ran good and exhaust cleaned up. Front bank ran rough and the haze was present. Both fueling actuators had the tops popped off while driving and we replaced the timing actuators for excessive side play. All had some debris in them but not much. All looked to be original equipment with 925k miles.

Then the next thing to do to find the hazing and smoking at cold idle is to slide the exhaust manifold away from the head a bit and fire it up. .. see what cylinder(s) it is.

Also to inspect it for wet exhaust valves... make sure it is not leaky valve guide seals.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-10-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #30
RE: CM871 poor power and fuel econ
Rebuilding this motor is probably in the not so distant future, but my pressing issue at the moment is figuring out why it’s throwing a 974 cab side code “tps low voltage” (according to the mechanic/insite). Just replaced the sensor again. All three sensors (I still have all 3) read the same voltage outputs at the sensor and at the inputs to the ecm. With a constant 5v supply to both APS and IVS circuits under all conditions, so I’m assuming it’s not a sensor problem. Motor running or not, throttle pedal depressed or not. But the thing throws the 974 code constantly. Idling in the shop or on the road. I have cleaned and polished every connector on the firewall multiple times and flushed with methanol. Just figured out that this thing had a pto and it’s been removed. Is there a secondary computer somewhere I should be checking for a aux throttle input??? Or any other ECM reasons that it would be throwing that code??
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04-10-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #31
RE: CM871 poor power and fuel econ
(04-10-2022 )Grounded Pilot Wrote:  ... Or any other ECM reasons that it would be throwing that code??

if the program does not match the engine ser# and/or that model make truck it can over-sensitive and throw TSP faults too.

Make sure the program in the ecm matches the truck/engine.

re-read my very first reply to this thread ...
(02-16-2022 )Rawze Wrote:  DEMANDATE PROGRAMMING...
first and foremost, assume the delete program is bad. Pull a copy of the program out of the engine and e-mail it to me for a proper review.
ref: http://rawze.com/forums/showthread.php?t...0#pid70220

You need to ensure the program in the ecm is correct and safe for that engine/truck and that the demandate was done properly.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-10-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #32
RE: CM871 poor power and fuel econ
Thanks! Yeah, I’m going to get the inline6 or nexiq adapter asap and get it copied. I’m really not confident in the ecm programming at this point. And I think the mechanic shop we work with does good work, but they don’t want to mess with the computers much other than diagnostics it seems. They copied the original ecm with the demandate program to the unit that’s in the truck now from what I understand, and what he remembers doing. From the paperwork, it just says “installed customer supplied ecm”. So not much help.

On that subject, which system is best to do Cummins/cat/Detroit all with one adapter?
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04-11-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #33
RE: CM871 poor power and fuel econ
Nexiq, but do yourself a favor and buy a legit one from snap-on or fleetpride. It's gonna cost you around $1,000.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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 Thanks given by: Grounded Pilot
04-11-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #34
RE: CM871 poor power and fuel econ
If all you have is cummins equipment, Many people don't want to invest $1,000+ into something they do not use but every so often, so an inline-5 or inline-6 adapter from flea-bay or obd2.com works well too for only about $300 bucks or so.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: Grounded Pilot , Andre_The_Giant
04-11-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #35
RE: CM871 poor power and fuel econ
Thanks again! And I will check with them if that is the way I go. My issue is that the guy that owns the truck has pretty much been soured to Cummins on this truck and is looking to go back to a Pre mandate Cat. So if I buy an adapter I want to make sure it has options for more manufacturers.

Also, would the CECU have anything to do with the TPS problem? Maybe the aux throttle for the PTO? I pulled the cover for the center console and the CECU and ABS were just jammed in the hole and not bolted (one screw in the CECU) and they are dirty and nasty. Also, the wiring for the PTO and air lime is just cut in the dash and stuffed in there. Not taped or capped. Trying to get them sorted out and see if there is a short in it somewhere.
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04-11-2022, (Subject: CM871 poor power and fuel econ ) 
Post: #36
RE: CM871 poor power and fuel econ
sounds like you have a real mess on your hands there. Owner should stop blaming cummins (as the manufacturer) for problems created by 3rd party shops screwing around and doing half arsed work.

Like rawze said, check out that programming. You could be chasing ghost problems or just be unaware of other faults/problems being hidden/suppressed by bad programming.


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