Please help solve my puzzle!

[Hammerhead]

(07-28-2016 )JMBT Wrote:  I am definitely considering it. If I can't get this figured out I WILL be going that direction. Just wish if that was going to be the end result I would have done it when the engine was still new! The engine would be in a lot better condition, and I would have a sh*t- ton more money in my pocket. Hell, I probably would have had to take up a hobby to spend it all!!!!

Might I recommend drag racing...
FYI, I have a dragster for sale since you're talking about extra money...just sayin

[Kenworth2012]

(07-28-2016 )JMBT Wrote:  I will be sure and check that. I noticed on the last forced regen (yesterday) that the inlet NOX was reading higher then the outlet. I thought it seemed odd, but then when the SCR catalyst temp cooled down after the regen it went back to normal, (Inlet high and outlet low). Both readings reported "stable" the whole time, so when it went back to normal I thought it was a product of the heating up of the catalyst. My engine's NOX sensor replacement history: inlet replaced 2 times and outlet replaced once, but the check engine light came on each time.
Very interesting info on the driving regens being based on time, and 36hrs makes since. When my truck was brand new the longest I would get between driving regens was about 1800 miles, which would be 36hrs at a 50mph average. Very interesting. Thanks again for the info.
I am waiting on parts for the exhaust leak, should be in tomorrow.

The inlet should read higher than the outlet. The inlet reads raw exhaust nox. The outlet reads def treated exhaust nox. I changed mine about a month ago. Yes they were $450 each from Cummins and take in the old ones for cores. $70 core charge. Each. Yes CM2250. This was the forth time the sensors were replaced. The first three times they were supposedly replaced under warranty. They may have used knock offs or they didn't change them. So, after following Rawze, I'm doing the work and using the heck out of Cummins quick serve. Lots of info there.

[Billdozer2]

(07-29-2016 )Kenworth2012 Wrote:  The inlet should read higher than the outlet. The inlet reads raw exhaust nox. The outlet reads def treated exhaust nox. I changed mine about a month ago. Yes they were $450 each from Cummins and take in the old ones for cores. $70 core charge. Each. Yes CM2250. This was the forth time the sensors were replaced. The first three times they were supposedly replaced under warranty. They may have used knock offs or they didn't change them. So, after following Rawze, I'm doing the work and using the heck out of Cummins quick serve. Lots of info there.

What kind of numbers are you/were you getting with those NOx sensors through Insite?

My truck was regenning more than normal and the DPF pressure differential was up into the 5's. I removed the DPF and cleaned/baked it. The DPF pressure numbers are down under 1 now, but the truck is still regenning every 5 hours or so. I checked the NOx sensor readings and found that the inlet is around 150-200ppm at idle and the outlet is around 50ppm. I'm not really sure what the numbers are supposed to be, but it seems ok. I haven't checked what the numbers are when driving. I do have a check engine light for SPN 4364 FMI 18. Truck has 389,000 miles and the NOx sensors have never been replaced.

Is there any sort of test that can be performed on the sensors so that you know they are no good before replacing? I really dislike guessing. Especially when it involves almost $1,000.

[Kenworth2012]

(07-31-2016 )Billdozer2 Wrote:  

(07-29-2016 )Kenworth2012 Wrote:  The inlet should read higher than the outlet. The inlet reads raw exhaust nox. The outlet reads def treated exhaust nox. I changed mine about a month ago. Yes they were $450 each from Cummins and take in the old ones for cores. $70 core charge. Each. Yes CM2250. This was the forth time the sensors were replaced. The first three times they were supposedly replaced under warranty. They may have used knock offs or they didn't change them. So, after following Rawze, I'm doing the work and using the heck out of Cummins quick serve. Lots of info there.

What kind of numbers are you/were you getting with those NOx sensors through Insite?

My truck was regenning more than normal and the DPF pressure differential was up into the 5's. I removed the DPF and cleaned/baked it. The DPF pressure numbers are down under 1 now, but the truck is still regenning every 5 hours or so. I checked the NOx sensor readings and found that the inlet is around 150-200ppm at idle and the outlet is around 50ppm. I'm not really sure what the numbers are supposed to be, but it seems ok. I haven't checked what the numbers are when driving. I do have a check engine light for SPN 4364 FMI 18. Truck has 389,000 miles and the NOx sensors have never been replaced.

Is there any sort of test that can be performed on the sensors so that you know they are no good before replacing? I really dislike guessing. Especially when it involves almost $1,000.

That outlet seems a little low and the inlet a little high. Mine is 120 on the inlet and 90 on the outlet at idle. Go to Cummins quick serve and download DESA test. Email cummins for a free 1 year license. Run the test and it will give a pass or fail on a number of components in the aftertreatment system. That code is for Aftertreatment SCR catalyst conversion efficiency . Most likely because of the NOX sensors. Troubleshooting guide also points to the sensors first. Also, search youtube for all the videos that rawze made for egr tune up, changing the IMAP, Delta p, and Exhaust pressure sensors, doing a forced regen and what to look for. There is a wealth of info on this forum and on you tube by Rawze.

[JMBT]

Kenworth2012, thanks for the reply.. Yes I think quick serve, insite, and Rawze are the way to go! Mine has been in the shop only once since new, and I now have 550K. The core charge on the NOX sensors must be new. I bought my last one 100K ago at a freight liner in Atlanta no core at that time. $400 for the 3 ft model, which both of mine happen to be. The shorter lead models (2ft and 1ft) were cheaper of course.
You are correct the inlet should be higher then the outlet, in the above post I just stated in backwards. During the regen mine were reversed, (inlet low, outlet high), then after the catalyst cooled back down to normal they switched back to normal or proper (inlet high, outlet low).
Billdozer2, I don't know for sure where the NOX numbers should be, but at high idle I am around 150 on the in and 30 to 40 on the out...I would guess the lower on the out the better!! If you are at 389K and never changed one of the NOX sensors you are doing great!! I changed my first one at 188K, and then there were more to follow.
I second Kenworth2012 on the DESA test, but be prepared it can run your motor at 1700 RPM for up to 10 mins while it is diagnosing. Not bad, just hard to listen to if you normally run your motor easy. I used to mine purring along at 1450.
By the way what kind of temps are you guys seeming during regen in the SCR? Just curious to see how they compare to mine.

[Billdozer2]

(08-02-2016 )JMBT Wrote:  You are correct the inlet should be higher then the outlet, in the above post I just stated in backwards. During the regen mine were reversed, (inlet low, outlet high), then after the catalyst cooled back down to normal they switched back to normal or proper (inlet high, outlet low).

Mine does the same when doing a regen. The outlet will be higher than the input. I'm not really sure how that is possible, I guess science. Once the regen is over, the input will be higher than the output, like how it should be. The catalyst can still be hot and it will read "normal".

(08-02-2016 )JMBT Wrote:  Billdozer2, I don't know for sure where the NOX numbers should be, but at high idle I am around 150 on the in and 30 to 40 on the out...I would guess the lower on the out the better!! If you are at 389K and never changed one of the NOX sensors you are doing great!!

Yeah at low idle I am around 150 input and 50 or so output. During regens, it will be about 180 input and 190-200 output. Science. While driving, if I am coming up to a hill and giving the truck "the full monty", the input will go as high as 500 and the output will match that and then slowly go down to the 200's. I don't have any fault codes for the sensors themselves. Just the catalyst efficiency code. But it seems to be working ok. Or what I think is ok.

From what I have been reading, I guess I'm doing ok at 389k on original sensors. I may be replacing them soon after I figure out why my DPF is filling up too fast.

(08-02-2016 )JMBT Wrote:  I second Kenworth2012 on the DESA test, but be prepared it can run your motor at 1700 RPM for up to 10 mins while it is diagnosing. Not bad, just hard to listen to if you normally run your motor easy. I used to mine purring along at 1450.

I'll have to get on that DESA test. Someone else on here talked about that test a few months back. I'll have to do a search. 1700 rpms huh? I hit 2000 once. That was interesting. The cooling fan was on too because I had the a/c on. Almost sounded like the space shuttle taking off from on top of a scrap metal pile. I usually fart along at 1350 and 62-63 mph.

(08-02-2016 )JMBT Wrote:  By the way what kind of temps are you guys seeing during regen in the SCR? Just curious to see how they compare to mine.

I just finished doing a parked regen and my SCR temps were pretty close to the DPF temps. Near the end of the regen, the DPF was 970 input and 1100 output. The SCR was 1000 input and 970 output.

[Kenworth2012]

(08-02-2016 )Billdozer2 Wrote:  

(08-02-2016 )JMBT Wrote:  You are correct the inlet should be higher then the outlet, in the above post I just stated in backwards. During the regen mine were reversed, (inlet low, outlet high), then after the catalyst cooled back down to normal they switched back to normal or proper (inlet high, outlet low).

Mine does the same when doing a regen. The outlet will be higher than the input. I'm not really sure how that is possible, I guess science. Once the regen is over, the input will be higher than the output, like how it should be. The catalyst can still be hot and it will read "normal".

(08-02-2016 )JMBT Wrote:  Billdozer2, I don't know for sure where the NOX numbers should be, but at high idle I am around 150 on the in and 30 to 40 on the out...I would guess the lower on the out the better!! If you are at 389K and never changed one of the NOX sensors you are doing great!!

Yeah at low idle I am around 150 input and 50 or so output. During regens, it will be about 180 input and 190-200 output. Science. While driving, if I am coming up to a hill and giving the truck "the full monty", the input will go as high as 500 and the output will match that and then slowly go down to the 200's. I don't have any fault codes for the sensors themselves. Just the catalyst efficiency code. But it seems to be working ok. Or what I think is ok.

From what I have been reading, I guess I'm doing ok at 389k on original sensors. I may be replacing them soon after I figure out why my DPF is filling up too fast.

(08-02-2016 )JMBT Wrote:  I second Kenworth2012 on the DESA test, but be prepared it can run your motor at 1700 RPM for up to 10 mins while it is diagnosing. Not bad, just hard to listen to if you normally run your motor easy. I used to mine purring along at 1450.

I'll have to get on that DESA test. Someone else on here talked about that test a few months back. I'll have to do a search. 1700 rpms huh? I hit 2000 once. That was interesting. The cooling fan was on too because I had the a/c on. Almost sounded like the space shuttle taking off from on top of a scrap metal pile. I usually fart along at 1350 and 62-63 mph.

(08-02-2016 )JMBT Wrote:  By the way what kind of temps are you guys seeing during regen in the SCR? Just curious to see how they compare to mine.

I just finished doing a parked regen and my SCR temps were pretty close to the DPF temps. Near the end of the regen, the DPF was 970 input and 1100 output. The SCR was 1000 input and 970 output.

If the outlet is going higher than the inlet, then they are going bad and will cause the 3582 code. That's exactly what mine were doing. Now, it's just me but I changed both at same time as a set. I've had this problem before and would change one then about a month later the other would go out. And all my problems started around 360K. Absolutely nothing prior to that. You may want to check the flow rate of the DEF injector if both NOX sensors are reading about the same at all times. I had to change mine at around 380K. During the DESA NOX sensor test, mine never went above 275ppm inlet and 200 outlet at 1700 rpm. Remember the outlet should always be lower than the inlet due to the DEF being injected into the exhaust prior to the SCR catalyst and passes the outlet sensor on the way out the exhaust pipe.

My DPF inlet temp will reach 1250, outlet temp 1200. SCR inlet 1150, outlet 1100.

What is your DOC inlet temp? Mine will hit 750. If yours is low could be the fuel doser or injector is clogged up with soot. Again, check out Rawze's video on a forced regen and what to look for on youtube.

[JMBT]

My DOC inlet never goes over about 650oF and usually stays in the low 6's. Quick serve says 550-750 is fine. My SCR usually remains a bit under the DPF temps, but still gets well into the 1000's, also the SCR in and out are nearly the same which I was told means there is no clogging occurring.
Sometimes I get the feeling Cummins doesn't even really know how these systems are supposed to act. Especially when they roll over 500K.
Bulldozer2, I think I will pull mine each out and very, very carefully wipe them off with a dry cloth before I replace either of them without a code. Each time I have replaced either before it was prompted by a code. We'll see.....