CM871 poor power and fuel econ

[tree98]

Yea program review is your next step. Temp sensor reading 72 deg. All the time is quite suspect of a bad demandate.

[Grounded Pilot]

That wouldn’t surprise me one bit!!

[Grounded Pilot]

This truck has been “quite suspect” since I started driving/working on it! Lol!

[Grounded Pilot]

(07-11-2022 )Grounded Pilot Wrote:  Good afternoon ladies and gents!! I have finally gotten more things straighten out on this truck. All 6 injectors are now replaced and my fuel mileage has come up to running in the high 5’s most of the time. It is still sluggish on throttle and the turbo seems to lag behind. When I run the engine status monitor it says “defueling due to insufficient oxygen(boost pressure)”. I know it says it will do that under hard acceleration but it will do it about any time you increase the throttle % unless you are deliberately very slow on the movement. It has new filters and a new turbo and actuator. Also a new airflow sensor and exhaust gas pressure sensor. The OEM ambient temp sensor reads 72° all the time but the intake temp seems to read correctly. Also, my fuel flow jumps around a lot. At idle it will jump from .8gph to 2gph and it will jump 5+gph while pulling. Any ideas or is that another bad sensor?

I finally got ahold of a Cummins inline6 adapter kit. I’m still learning how to run the insite program and I need guidance on how to pull the programming to send it to Rawze for review? And where to send it Mr Rawze?

Thanks all!! I really appreciate your help and knowledge!

Another question that pertains to the above post. What sensors are used to give the ecm its torque and HP readings? If I get this thing up in the 1600-1750rpm range sometimes it will all the sudden start pulling like somebody stepped on its tail! And it will surge if the rpm starts picking up to quick, especially in 3/4 holes low range and 1/2 holes high range. (13 speed). Have not caught it yet when I have the system logging, so not sure if its getting the "defueling due to oxygen" engine status. BUT, I see on my Scanguage D display when it does this that the fuel flow reading seems to stabilize some and begin climbing consistently rather than bouncing around?? Is that and indication that the fuel flow/pressure sensor is faulty?? No codes, but my exhaust gas pressure sensor was broke off and I didn't get a code (also didn't have insite then either, just the scanguage and what the mechanic said). I've had to replace a bunch of sensors due to corrosion and malfunction, so just checking if there are more that I may need to check/change to make sure the ecm is getting the proper data.

[Rawze]

(07-17-2022 )Grounded Pilot Wrote:  ... What sensors are used to give the ecm its torque and HP readings?
...

There are no sensors that do that directly or indirectly.

Just about every engine sensor can effect how it performs. The most relevant usually being the exhaust gas (back-pressure) sensor, the IMAP sensor, etc. etc.

Your descriptions point towards some kind of severe neglect of the engine sensors and systems in its past. This is usually coupled with a lot of mechanical neglect too.

also might want to do an overhead valve adjustment and injector leak tests too...
http://rawze.com/forums/showthread.php?t...8#pid67948

[Grounded Pilot]

(07-17-2022 )Rawze Wrote:  

(07-17-2022 )Grounded Pilot Wrote:  ... What sensors are used to give the ecm its torque and HP readings?
...

There are no sensors that do that directly or indirectly.

Just about every engine sensor can effect how it performs. The most relevant usually being the exhaust gas (back-pressure) sensor, the IMAP sensor, etc. etc.

Your descriptions point towards some kind of severe neglect of the engine sensors and systems in its past. This is usually coupled with a lot of mechanical neglect too.

also might want to do an overhead valve adjustment and injector leak tests too...
http://rawze.com/forums/showthread.php?t...8#pid67948

Yes sir, this thing has seen a hard life. Its taken the better part of a year since my boss bought it to get to this point with it. Replaced all 6 injectors, all fueling/timing actuators, exhaust gas sensor, map sensor, cam, turbo, and figured out the E,G,R system was demandated (didn't know that when it was purchased) along with the D,P,F system (did know that one) and both were done poorly from the looks of it.

It ran great to start with. Good power, decent fuel mileage but started losing power/fuel mileage right before the cam went bad. Then it has been a cascade of issues since and have gotten it back to respectable power and pretty good fuel mileage. But still not right. Like sometimes it will act like its fully loaded climbing a hill empty.

[tree98]

Have you had the program looked at yet ?

[Grounded Pilot]

(07-18-2022 )tree98 Wrote:  Have you had the program looked at yet ?

I’m in the process of getting the necessary downloads on my computer to get it pulled and to Rawze. Hopefully get it done tonight when I stop. Had to download over a hotspot connection so it has taken some time! Lol!

[Rawze]

Reviewing the program that was sent to me.
what I see at a glance...

* DPF delta-P, DPF inlet temp, DPF Outlet temps sensors not disabled properly.

* EGR Delta-P sensors not disabled properly.

* Load based speed control is active. This will make the truck feel sluggish all the time.

* regen protection derates are not fully disabled.

* Some of the after-treatment management is not switched off.

* Some of the after-treatment derate logic is not switched off. This could lead to an unexpected derate at some point.

* very little mode control management has been done. The engine is still able to jump out of its non-egr operating mode. This can lead to unstable power/torque,. or other harmful conditions depending on environment.

* EGR gas manager influence on the turbo has not been disabled. This can make the turbo over-spool sometimes.

* All EGR flow requests are still active, yet the egr valve is disabled. This leave the ecm simply assuming that egr gas is still going into the intake.

* Injection timing has not been corrected at all and is moderately harmful to the engine.

* crank case sensor emissions control is still active.

* doser injector is not fully switched off.

* regen and permit switches are still active.

* EGR valve control logic is not fully switched off.

* Aux emissions are still active.

* fuel controller has a known software bug in it that will randomly limit fuelling at times. Talked about in this post: http://rawze.com/forums/showthread.php?t...4#pid71234

* Fuel air mix control has not been corrected.

* the turbo is set waay too high for a W900 truck. It will over-boost/over-spool and cause harm to itself.. and cause fuel mileage + power losses due to it fighting itself all the time.

==================\

Welcome to the bad delete club!.

This is the typical hack-n-slash garbage-can delete where some complete moron thinks that if they do as little as possible and only block codes, then jack with the turbo to try to make it run better.. and hope there is magic fairy-dust leprechauns inside the the ecm that will make everything all better. -- What a damn mess this one is.. is all I can say.