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+--- Thread: exhaust back pressure sensor issues (/showthread.php?tid=8147)
exhaust back pressure sensor issues - S_Premo06 - 04-05-2022
I have three Cummins CM871 engines that I am having back pressure code issues, they all are temporarily cured by installing new ETP sensors but are very short lived before failing again. One engine has been doing great so far after I installed a Cummins sensor istead of {after-market brand}. Any ideas??
RE: exhaust back pressure sensor issues - Rawze - 04-05-2022
First of all, the engine sensors should ALL BE OEM ONLY SENSORS!@. It is quite a dumb idea to use aftermarket sensors for a $40,000 commercial engine that someone has to rely on for their living.
NEXT: You need to copy the programs out of those ecm's (using calterm) and send them to me roe a proper review. For all you know the damned engines might be trying to still warm up DPF canisters that are no longer functional. Bad delete programming is a huge plague in the trucking industry and one of the common symptoms of this is excessive exhaust back-pressure from the engine when it perpetually gets stuck trying to warm up a missing DPF canister because some complete idiot decided to unplug all the system and hollow it out, end then blocked the faults codes instead of making an actual proper program for the engine.
RE: exhaust back pressure sensor issues - S_Premo06 - 04-19-2022
(04-05-2022 )Rawze Wrote: First of all, the engine sensors should ALL BE OEM ONLY SENSORS!@. It is quite a dumb idea to use aftermarket sensors for a $40,000 commercial engine that someone has to rely on for their living.
NEXT: You need to copy the programs out of those ecm's (using calterm) and send them to me for a proper review. For all you know the damned engines might be trying to still warm up DPF canisters that are no longer functional. Bad delete programming is a huge plague in the trucking industry and one of the common symptoms of this is excessive exhaust back-pressure from the engine when it perpetually gets stuck trying to warm up a missing DPF canister because some complete idiot decided to unplug all the system and hollow it out, end then blocked the faults codes instead of making an actual proper program for the engine.
all of these engines are factory with functioning DPF systems, they all do proper and complete burns with good temps. how do i go about copying the programs if i do not have calterm? i have the bosch service tool that i can try to get you that?
RE: exhaust back pressure sensor issues - Rawze - 04-19-2022
(04-19-2022 )S_Premo06 Wrote: ...
all of these engines are factory with functioning DPF systems, they all do proper and complete burns with good temps. how do i go about copying the programs if i do not have calterm? i have the bosch service tool that i can try to get you that?
if the engines are not deleted (de-mandated)and all the emissions systems are still in tact then there is no need to send me the program out of it. Just verify that the program matches the engine by its ser# and quickeserv.com says, and that some moron did not install a different program in to try to up the horsepower.
Another thing to do is full EGR tune-up if it has not been done. This ensures that other sensors are not feeding the ecm the wrong information, and that egr valve and pipes are not clogging/hanging up.
it is not normal for an ISX to have exhaust gas pressure sensor fault codes. What is the exact set of cummins fault codes that are coming up on them?.
Also, you should invest in an inline-6 adapter and Insite. it is far better for cummins engines (and only costs about $300 bucks or so usually) than any other aftermarket scan tools for cummins.
RE: exhaust back pressure sensor issues - Mr Hagg - 04-19-2022
Can you provide the actual code? SO we can look into what its is calling for. As Rawze stated those aftermarket sensors are total waist of time. Trust me I fell victim of it too. And seems everytime I have a truck in here with that code its a bad sensor or tube is clogged up...
RE: exhaust back pressure sensor issues - marek4792 - 04-19-2022
Tried an aftermarket Exhaust Pressure Sensor too (stealership didn't have oem), didn't make it across town before it threw 3 injector codes. Put old sensor back on and all was good and bought OEM at another stealership.
RE: exhaust back pressure sensor issues - S_Premo06 - 04-29-2022
fault codes are as followed,
2764
125
2448
2215- fuel pump has since been replaced and this code is no longer on
2554
2374
I removed the DPF and found it to be melted so I replaced it and driver did a regen on it, I was not there to watch the numbers so i'm not sure what temps it hit. The driver took the truck and made it to iowa from forest lake mn and the low boost light came on. there is severe black soot coming from the stacks.
RE: exhaust back pressure sensor issues - tree98 - 04-29-2022
Why didn't you figure out why the dpf melted before you slapped a new one on and sent the truck out ? Also why did the driver do a regen on a brand new dpf? Your a little lite on information here.
Could be low boost because of a blocked exhaust, like from another melted dpf.
RE: exhaust back pressure sensor issues - Rawze - 04-29-2022
(04-29-2022 )S_Premo06 Wrote: fault codes are as followed,
2764
125
2448
2215- fuel pump has since been replaced and this code is no longer on
2554
2374
I removed the DPF and found it to be melted so I replaced it and driver did a regen on it, I was not there to watch the numbers so i'm not sure what temps it hit. The driver took the truck and made it to iowa from forest lake mn and the low boost light came on. there is severe black soot coming from the stacks.
FIRST of all, what you have described in your posts so far points directly towards severe engine and emissions system neglect.
(just generalizing here, not directed towards anyone specific)...
Someone should not be blaming the equipment for most of these problems, but instead, should taking a hard look at their business model on how to keep their trucks maintained properly. The collection of bad decisions of neglecting is why someone becomes the proud owner of these kinds of issues that costs a truck owner endlessly. What has been described so far is a truck/engine/emissions system in dire straights, and failing due to sheer lack of anyone doing anything on this truck except running it off to every shop they can find, only AFTER the CEL lights come on .. then wondering why it runs them into the ground financially, and keeps having repeated break-downs.
MOST OF THE TIME, PEOPLE PURCHASE THESE TRUCK ALREADY IN THIS CONDITION OF NEGLECT ... SO IF THAT IS THE CASE THEN WELCOME TO REALITY!... Where trucks are run into the ground and then the next guy is left with the aftermath and added expenses of getting it back right... WHICH SHOULD HAVE BEEN ESTIMATED INTO YOUR COSTS ON PURCHASE.. AND DONE BEFORE THE TRUCK WAS PUT BACK ON THE ROADS!!!... AND NOT AFTER SOMEONE GLEEFULLY HOPED FOR THE BEST LIKE A FOOL AND DID NOTHING TOWARDS ENSURING ITS RELIABILITY BEFORE HAULING FREIGHT WITH IT!.
-- IE>. This typical cheap-minded business strategy of "jumping over a dollar to save a dime" type of serious neglect and zero regard towards keeping their equipment trouble free. --- THIS TYPE OF "IGNORE EVERYTHING TILL THE LIGHTS COME ON" BLIND-MAN GARBAGE === NOTHING BUT PROBLEMS AND IF THIS WAS A BUSINESS DECISION BY SOMEONE IN HOW THEY RUN THEIR TRUCK(S) DOWN THE ROADS .. THEN I WILL BE THE ONE TO TELL SOMEONE REAL FAST THAT THIS IDEA JUST SIMPLY SUCKS!.
- And if this thing got this way UNDER YOUR CARE/OWNERSHIP... THEN YOU NEED TO WAKE UP AND START SMELLING THE FACT THAT THESE THINGS NEED ACTUAL REGULAR MAINTENANCE AND CARE, TUNE-UP WORK, ETC. .. BEYOND JUST THE DAMN OIL CHANGES!!!.. AND LONG BEFORE ANY CEL LIGHTS BEGIN TO PLAGUE THEM!!!. -- and there are no repair shops that ware going to do ANY Of THESE THINGS!. It has to be done by the truck owner, or someone that is specifically being paid to do this type of yearly preventative maintenance item/cleaning/tests/adjustments/egr-tune-up type of regular interval work to the truck(s).
Now, with the rant/wake-up call out of the way,...
Those fault codes come up as...
=============
2764 - Exhaust back-pressure (exhaust gas pressure) sensor reading too high.
125 - Intake (boost) pressure has lower than normal reading.
2448 - Low coolant.
2215 - Low Fuel pressure.
2554 - Exhaust back-pressure sensor has been unplugged, or has a bad wiring connection.
2374 - Exhaust back-pressure sensor is shorted out, or has bad wiring connection.
=============
This stuff is not rocket science. Seems pretty obvious to me...
FIRST OF ALL... You say that the DPF was melted. - THIS MEANS THE SCR ELEMENT AND THE DOC ELEMENT ARE TOAST TOO!... PERIOD!. -- THEY ARE NO GOOD!.. THEY HAVE BEEN COMPROMISED!... AND THAT THING WILL NOT HAVE RELIABLE EMISSIONS SYSTEM ON IT UNTIL THEY ARE ALSO REPLACED!. - This is also reflective as such if you are seeing black smoke out of the stacks... regardless of what the engine problems are at this point.
A melted PDF filter = THE SCR ELEMENT WAS COMPROMISED WITH SOOT, unburnt liquid FUEL at some point, ASH, AND DEBRIS. - It is now no good, and very likely it will not function correctly no matter what you do at this point.
A melted PDF filter =the DOC Element is also highly likely no good eiother, as it is usually liquid fuel + severe excess temperatures that causes the DPF to melt like that.. This causes damage, weakens to the DOC element as well, although it is not typically visible.
So... Expect to have to change out her SCR element AND the DOC element at this point.
HOW DID IT GET THAT BAD!?... MOSTLY ENGINE NEGLECT.. Just like I mentioned above. Those things do not make soot. They do not make fuel. they do not melt or clog up, or get in that bad of shape on their own. IT IS ENGINE PROBLEMS DUE TO NEGLECT THAT CREATE THOSE EMISSIONS SYSTEM PROBLEMS!.
If the 2554 and 2374 codes keep coming back then there is obviously still something wrong with the exhaust back-pressure sensor itself or the wiring going to it.
Also, the circuit feeding it likes to clog up. I mention this in one of my oldest egr-tune-up videos here, at 9:08 in the video:
Has anyone bothered to do a full egr-tune-up on the engine yet?. Replace sensors that are old, or carbon packed, cleaned out the egr valve and the piping?. This should have been done yearly .. not after the problems got this bad.. but late is better then never. Has anyone done this thoroughly?
NEXT, it is clear that this engine is getting higher than normal back-pressure issues and lower then normal boost. - SOMEONE NEED TO PRESSURIZE THE CAC AND CHECK IT FOR LEAKS!. They also need to pressurize the WHOLE ENGINE. Front and back of turbo plated off and the entire engine pressurized to 15-20 psi and check for intake, egr system, and manifold, etc., leaks.
ALSO what about the engine air filter?. Is it new?... and someone ensured it was not restrictive?.
Anyone bothered to inspect the exhaust for restrictions?.. check again, the faces of the DOC, DPF, SCR, etc. and also check for the "Volcano" scenario?.
Volcano Scenario ref: http://rawze.com/forums/showthread.php?tid=283&pid=1807#pid1807
Also .. the turbo on the ISX will over-work itself if that exhaust system is still clogged up, or that intake/boost system is leaky (or clogged) ... and guess what .. A MELTED DPF AT ONE POINT, points towards a BAD DOSER INJECTOR and/or exhaust leaks somewhere. - Has anyone bothered to find out HOW the dpf got melted and has since, replaced the Doser injector to prevent another melt-down, and ensured there were no exhaust system leaks?... instead of some repair shops half-arssed, band-aide-repairs, and only replacing what was bad? then everyone just hoping for the best instead of going thru that engine and ripping apart its egr and emissions system to actually clean, replace sensors, etc. solve some problems!?.
I bet it did not have these issues when the engine/truck was shiny new... not until it had about 3+ years worth of sheer neglect that is. I.E.> These system can be fixed correctly. They can be maintained where they do not end up in the bad conditions that you described... BUT IT TAKES KEEPING AFTER THEM BEFORE THE CEL LIGHTS PLAGUE IT!. This is where modern trucking and truck ownership fails. Tt is a serious lack of understanding that these things CANNOT HEAL THEMSELVES like people can. They degrade and unless someone takes it all apart and keeps after it regularly.. it becomes nothing but a big headache... and you bet your arsse that the network of OEM repair shops across this fine nation.. COULD GIVE A DAMN ABOUT MAKING THEN RUN RIGHT... but instead are only trained on how to put out the tree that is no on fire right next to you so that you squeak a bit less .. MEANWHILE THE WHOLE FOREST AROUND YOU BURNS TO THE GROUND!@.
As far as the low fuel pressure code... Has anyone bothered to do a second leak-down test on the fuel system to ensure it is not leaky again?.
ref: http://rawze.com/forums/showthread.php?tid=7915&pid=69262#pid69262
low fuel pressure codes indicate there is still something wrong. START by checking it AGAIN to ensure it will pass leak down test. After that, look for fuel restrictions,. etc... or maybe a bad sensor or wiring for the fuel pressure sensor.