CM871 code 2973

[Valley11]

I have a CM871 in a T800 Kenworth demanded 3 years ago by a fairly reputable guy out of Ontario. Over the last year code 2973Intake manifold 1 pressure - Data erratic, intermittent, or incorrect has been coming up once in awhile with a full load. Now it comes active 4-6 times on a 2 hour trip. When code is active boost pressure is lost and stays at 0PSI, when code is not active I can build 36-38PSI. It will go active in higher gears at 1600-1700rpm goes away after awhile and truck runs fine until it happens again. I monitored some values on the last trip but can not seem to find if they are in spec or not. Any help would be greatly appreciated.

I have found that the crankcase pressure sensor has been disable and no code shows when I disconnect it.
Intake manifold pressure went as high as 78.5 inHg usually ran between 40-65 inHg
Exhaust gas pressure went as high as 158 inHg usually 80-120 inHg
Barometric pressure was 28.5-29.3 inHg according to weather network local pressure was 30.7
Intake manifold air temp bounced all day started at 50F then dropped 9-12F and then ran around 22F It was -27C -38C with the wind
Turbo speed top was 103000rpm
OEM temp is set at 72F never moves with truck out in the cold or in the heated shop
If anyone could tell me if some of these tubers seem correct or not or any insight on what I could check next

[Rawze]

Just about everyone who comes on this forum, all swears by their "reputable guy", almost always learns the hard way that their program has some sort of serious issues that may or may not show up right away. Most of the delete programs that people make, copy, steal off others, buy/sell, etc... then shove into other people's engines will shorten the hell out of the life it as well.

Pull a copy of the program out of the ecm and e-mail it to me for an inspection of safety and stability. -- AT LEAST eliminate the questionability of it if you actually value your engine and its longevity/stability.

I would begin by doing this first and foremost, because for all you know, it could be jumping operating modes unpredictably for some reason or another.

As far as programming is concerned,.. if it has been 3+ years since it was done, even if it has the best programming on the planet in it,.. It is well past due/ in dire need for some updates that have to do directly with power boost, etc. to correct some issues that are well known on the 871's.

ALSO, when is the last time you replaced the IMAP, exhaust gas pressure, and other important engine sensors?

What mods, things have been done to it mechanically?

Does the engine still have its factory VG turbo?

Has the crank case filter been drilled out? -- or are you using the cummins maint.free one?
ref: http://rawze.com/forums/showthread.php?t...376#pid376

Are the exhaust cans (DOC and DPF) 100% hollow? - Exhaust as open as possible? -- or something else?

[Valley11]

(02-21-2020 )Rawze Wrote:  Just about everyone who comes on this forum, all swears by their "reputable guy", almost always learns the hard way that their program has some sort of serious issues that may or may not show up right away. Most of the delete programs that people make, copy, steal off others, buy/sell, etc... then shove into other people's engines will shorten the hell out of the life it as well.

Pull a copy of the program out of the ecm and e-mail it to me for an inspection of safety and stability. -- AT LEAST eliminate the questionability of it if you actually value your engine and its longevity/stability.

I would begin by doing this first and foremost, because for all you know, it could be jumping operating modes unpredictably for some reason or another.

As far as programming is concerned,.. if it has been 3+ years since it was done, even if it has the best programming on the planet in it,.. It is well past due/ in dire need for some updates that have to do directly with power boost, etc. to correct some issues that are well known on the 871's.

ALSO, when is the last time you replaced the IMAP, exhaust gas pressure, and other important engine sensors?

What mods, things have been done to it mechanically?

Does the engine still have its factory VG turbo?

Has the crank case filter been drilled out? -- or are you using the cummins maint.free one?
ref: http://rawze.com/forums/showthread.php?t...376#pid376

Are the exhaust cans (DOC and DPF) 100% hollow? - Exhaust as open as possible? -- or something else?

IMAP sensor was replaced 2 years ago and put new one in again 2 days ago. Exhaust gas pressure sensor changed last year. Not sure what other sensors I should be replacing. Was going to replace barometric pressure sensor trying to locate it and from what I can find looks like it might be zip tied to wiring harness under the ECU.

It still has factory VG turbo passed calibration today.

Be honest I haven’t taken the crankcase filter out to look. I will check it tomorrow. Just came across today that could not monitor it and found it was disable and can’t find how to enable it or if the program removed it.

The cans were not 100% hollowed I fixed that last night they are all clean now. There is blocker plate on intake after egr and one before egr cooler. All parts are still in place.

[tree98]

[/quote]
The cans were not 100% hollowed
[/quote]

This is a tell tale sign of a bad delete.

[Rawze]

It is not unusual for a delete program to disable the crank case filter... that in itself will not cause harm on its own, as long at the truck owner is aware if it and the cc filter is properly dealt with ... BUT!!!-- The person doing that job should have well informed the truck owner(you) to either drill out that CC filter, perhaps like shown in the link I provided,... OR HAVE TOLD YOU TO use the cummins maint-free filter, as the maint.free one (link: http://rawze.com/forums/showthread.php?t...50#pid8950 ) from cummins is simply a drilled out housing with no element in it.

because ... <- A CLOGGED CC FILTER CAN DEFINITELY CAUSE TURBOCHARGER FAILURES! among many other problems like the engine brake harness bleeding oil, various gaskets, covers, seals, etc. leaking and bleeding oil, and several other issues related to too much pressure in the enigne under its valve cover as it build up.

As far as the EGR cooler blocked off,.. there is nothing wrong with stopping the exhaust gas flow through it (assuming you live in a country that allows such mods), but NEVER IMPEDE THE COOLANT FLOW through it. Hopefully the coolant flow through it has not been blocked or altered. Biggest issue that i see people do when blocking exhaust flow between the exhaust manifold and the egr cooler though, is that they use a blocking-plate they got off the internet and IT IS NOT THICK ENOUGH to hold back the 80 - 90 PSI+ of hot exhaust gas pressures behind it for long periods of time (many years), and they break apart, or get etched through, or corroded, and many other issues. <- If it break apart/cracks under these kinds of stresses, then the pieces will go through the turbocharger, destroying it. <- nothing to play with.
That plate should be at least as thick as a person's thumb, and made out of no less than 304-grade stainless, or it will eventually fail. Here is further discussion on this, that also shows an example of a decent one at the end of the thread ... http://rawze.com/forums/showthread.php?t...7#pid25737

[Rawze]

I was sent the program from your engine. Looking it over, here are the things that are considered red flags...

* Someone attempted to strengthen the engine brake settings by increasing turbocharger VG positions during engine brake operations. This has the serious potential of causing the engine to drop a valve at high rpm and engine brake at maximum settings. This is a dangerous thing to do and this could cause someone to loose their engine, crack their head, etc. if the piston strikes an exhaust valve due to too much lag because of excess exhaust back-pressure by the high settings that someone put in the file and is demanding from the engine.I have seen many people who make this mistake, then claim they made the engine brake stronger not knowing the consequences, and I have seen many failed engines for just this issue alone when someone gets into that situation where they need that engine brake on high, and end up at 1700, 1800, 1900+ rpm,.. and boom!,.. engine destroy itself for no apparent reason. MOST people keep their rpm in check during engine braking, and that is great, but it is that one time that it will save your arsse, or prevent that brake fade going down 4'th july, donnar, or grapevine, or some other mountain,.. but what good is this protection/system if someone has jacked it up to the point of causing engine failure at the point where it may be needed the most?--- Another one of the more common things I see people who do not know how these engines work, end up destroying them.


* The egr actuator logic has not been properly turned off. Blocking codes were added to the program to prevent the alarms from showing in the dash of the truck were used to mask this error/descrepency.

* The EGR delta-P sensor logic was also not properly turned off. Same thing, again, blocking codes were added to the program to prevent the alarms from showing in the dash of the truck were used to mask this error/descrepency.

* The DPF Doser injector logic was also not properly turned off. Same thing, again, blocking codes were added to the program to prevent the alarms showing in the dash of the truck were used to mask this error/descrepency.



* A valid attempt to run the engine in its factory non-egr operating mode was made. This is far better than a lot of bad programming that I have seen, ... However ... The method that was used (simply fooling the egr temp sensor), has been shown to not be 100% reliable on older trucks that may have other less obvious issues. It has been seen that sometimes, when using only this method, it can jump out of this mode, causing instability when the engine is in extreme weather sometimes, when sensors are reading wrong, or other factors. <- This method is certainly out of date, and there is definitely a need for more improved methods to be used/applied. Since this is the case, It would not surprise me if this may be part of the issue you are seeing now, but it also may not be. - Only testing the engine live and observing what operating mode it is staying in while it is acting up would reveal if this is part of the issue or not.

* All derates and shutdowns are still active for the engine. <- Some ppl would say that this is ok to leave all this stuff on, but now you are experiencing sudden boost pressure and other strange things, likely with no codes in the enigne to tell you what has happened. For all you know, the derate for exhaust temp, CAC leak detection, Turbo derates for a turbo that may be getting weak, and about a dozen other reasons of sudden unexplained power losses may be occurring. since there have been many codes blocked from being allowed to show up, this could make the thing very difficult to troubleshoot, and there is always the risk of thiat engine laying down on you for one of these now somewhat masked problems. <- Bad practice to leave all that stuff on and the emissions and other systems of the truck suppressed/unable to tell you what is wrong. - This should be corrected, as the only derates and/or shutdowns that should be still active, should only be for oil and/or coolant, nothing else. This is another sticky-point that could be causing your strange boost-loss problems, but only thorough testing of the engine and its operating states would reveal it. Though some would disagree, I own a truck too, and As far as I am concerned, it is a mistake to turn off all those system yet leave these derates and shutdowns all on making for an unpredictable condition, or engine leaving you on the side of the road somewhere because it refuses to run.

=============

That program certainly needs to be updated and repaired. That would be your first move, and after that, you can then start looking at hardware issues that may have caused things to suddenly change, as like you said, at one point it seemed to run fairly ok. <- there is also room for improvements to how the engine runs and its efficiency if things are done in the right ways, as the person who did your 'de^lete' program did not apply any of them at all. They left the derates power and other tables in the ecm from the factory, and this is not optimal when there is no more egr gas being sent into the intake.


You also need to ensure it is not one of those still active derates getting it. You need to pressurize the CAC, and then the whole enigne to ensure there are no air leaks between the intake of the turbo and the exhaust of the turbo. use blocking plates and pressurize it up to 30 psi and check every gasket, seal, component, your egr block-plates that were installed, that CAC unit, and everything else.

Programming aside, You should also adjust the overhead valves and do an injector leak test, etc. to ensure you do not have other issues, and HOPE LIKE HELL you have not cracked the head between the valve seats because of the engine brake being set up too high.

[Valley11]

Thank you for all the info. The software will be corrected next week and will then proceed in checking out the rest of the engine and see if issues still arise or if I get away luck with just getting the software fixed.

[Rawze]

(02-21-2020 )Valley11 Wrote:  Thank you for all the info. The software will be corrected next week and will then proceed in checking out the rest of the engine and see if issues still arise or if I get away luck with just getting the software fixed.

Since the file only had some easily correctable mistakes + was simply out of date, I made it safe (set engine brake tables back to their factory normal), repaired and updated it, switched off the shutdowns and derates except for oil and coolant, then sent it back to you. Your welcome to use it if you like, so that you don't have to wait for Uni to troubleshoot what might be wrong.

I also lowered the turbo mapping/programming slightly to reduce the boost by a touch (but not the power or torque). You say it was getting to 38 psi, but the overall tables looked too high for a T800 in general. - I suspect your going to find either a boost leak somewhere, perhaps a CAC leak?, your turbo is a bit weak?, or some other air related issue? like maybe the egr piping broken somewhere? letting exhaust or intake gas escape?- unsure... so I put it to what should be expected just as a precaution so that it does not over-boost if you do find out why. The truck will make the same if not slightly better HP/torque for its power rating (~550-ish hp) with 36-37 psi no problem otherwise.

[Valley11]

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.