2011 f750 Cummins idle only

[tonybullitt]

Friend of mine has this truck. It's a rollback tow truck. Guy tried clearing codes for him said was def codes still on idle only. Any info available to a f550 and smaller Ford tech like me?

[tonybullitt]

I retrieve active codes 1569:31 and 5246:00 they come right back if try to clear. my scan tool doesn't even give description

[JoeR]

1569-31   Engine Protection Torque Derate Condition Exists.

5246-0     SCR Inducement Severity Data Valid, but Above Normal, Most Severe.

 

This code can't be cleared.  In order to make it go away, and clear the derate, you have to run the SCR Performance Test, or SCR System Test  (depending on which software update is in the truck).

 

You can run the test with Cummins Insite, or a Snap-on Pro Link.  Maybe others, but I don't know that for sure.

 

Before running the test you'll need to fix it.  90% of the time I find dried DEF on the DEF Injector and lots of DEF deposited in the decomposition tube.  Take it off, wash it out with water, clean the injector tip with hot water, then run the test.  If it passes, the derate will clear.

 

Joe

[tonybullitt]

Thanks for the info. He recently bought this truck and they have agreed to fix it.

[tonybullitt]

Salesman said it's had a lot of $ spent fixing this problem recently. I should say attempting to repair

[JoeR]

Salesman said it's had a lot of $ spent fixing this problem recently. I should say attempting to repair

 

Unfortunately I see it all the time.  It's not a terrible code to diagnose on these.  Cummins gives you NOx in and NOx out of the SCR.  They also give you NOx adaptation factor on both sensors.  When a Cummins has trouble with NOx conversion, they begin shifting the NOx adaptation number.  

With that data and EGTs, it's not that bad to diagnose.  

I read the Freeze Frame to see what NOx adaptation is.  If it's off by more than 100 ppm, there's trouble.

I perform a DEF injector test.  I never care about the fluid volume.  Just the pattern.  If the pressure is good during the test, the volume will be OK too (at least from what I've seen).

I look inside the decomposition tube.  If there's dried DEF, I remove it and clean it.  

If there's DEF inside the SCR, I make sure the software is current and perform the SCR System Test.  The new test is hot enough for crystal sublimation, and will clean the SCR.  Early calibrations only do an SCR Performance Test, with no crystal sublimation.

I drive it to see if I get good NOx conversion when it is dosing DEF, and that I see a good temp rise across the SCR at the same time.

 

Note the NOx Corrected numbers here in this Freeze Frame.  Also not the SCR is not getting hot.  

https://www.flickr.com/photos/54428295@N05/34978734073/in/dateposted-public/

 

DEF Injector removed.  Look inside.  Lots of dried DEF deposited.

https://www.flickr.com/photos/54428295@N05/34978733953/in/dateposted-public/

 

 

I have never seen a bad SCR on a Cummins, but as they get older I'm sure I will.

Also good to know, if the truck has no NH3 sensor, then it is NOT a closed loop system.  It makes no attempt to adapt the DEF injection rate to compensate for low NOx conversion.  

[tonybullitt]

Wow, awesome information. When he gets the truck back I will have to check the pids. I have the otc encore. I will have to see what it will let me do.

[JoeR]

Wow, awesome information. When he gets the truck back I will have to check the pids. I have the otc encore. I will have to see what it will let me do.

 

Those will read the J1939 HD Standard Data.  It's kinda like OBD2 Generic Data for trucks.  However there are a LOT more available PIDs.  You should be able to see the EGTs, and maybe one NOx sensor.  I think that's about it though.  I don't recall ever seeing NOx adaptation in HD Standard.  It will be interesting to see what they find with it. 

Joe

[tonybullitt]

He said they found def injector plugged.

[JoeR]

Cool.  Do him a favor.  Pull that injector and look in the hole.  If there's a chunk of dried DEF in there, take the band clamps off, drop the tube and wash it out with water.  If not, he's gonna find himself in derate again.

Joe

[tonybullitt]

Cool.  Do him a favor.  Pull that injector and look in the hole.  If there's a chunk of dried DEF in there, take the band clamps off, drop the tube and wash it out with water.  If not, he's gonna find himself in derate again.

Joe

Thanks will definitely do that. Tony

[tonybullitt]

He is having issue with this truck again. He had the engine replaced and they have thrown some parts at it in the last few months. Any advise on this code. My otc encore doesn't have alot of pids but ecu at 3k seems high to me

 

[Keith Browning]

Wow that is hot! 

BTW for me to look anything up in Cummins I need an engine serial number. ESN

[tonybullitt]

I will get the esn number. Any ideal what that pid is?

[tonybullitt]

Hope this helps

[JoeR]

3251-16 is DPF Backpressure Sensor above Normal, Moderately Severe. 

It's gonna derate if the backpressure gets any higher.  So it looks like this truck is still having regen troubles.  Any chance you csan get your hands on a scanner that can show Regen History?  It would be helpful to know what's going on with it.

 

If I had to guess, and I do, I'd bet the data is an error in the scanner.  There's no code for it, and there's no way that sensor would ever have a range that wide anyway.  So unless I was chasing a code for it, I'd ignore that PID.  

 

Joe

[tonybullitt]

No I don't have access to any different scanner for medium duty. I figured that had to be an error on that pid. I made an account on quickserve.cummins  as an owner and it shows fault 3251 as dpf intake temp sensor high. That would make me want to look into the egt sensors based on my experience with ford egt. Would it be worth while to ohm egt when cold. Or without a better medium duty scan tool am I just pissing around. Previously I told him at my end with my limitation on scan tool and info. But with the shops he has working on it throwing parts at it and his frustration I am trying to be helpful.

[JoeR]

You're looking at the code on J1939 HD Standard with your scanner.  Quickerv is showing you the Cummins Codes, which you don't have access to.

Joe

[tonybullitt]

Ok that's what I was afraid of

[tonybullitt]

I wonder if that's what the guys at the shop are doing also chasing wrong code. Is there a way to know what Cummins code ppt I should follow on quickserve?

[JoeR]

The Cummins Code is 1921.  You can follow that on Quickserv.  You're gonna need to watch the DPF Backpressure PID.  On the Governor it should be less that 1"Hg, or .5 PSI.  

Check to see if it is close to 0 PSI KOEO.  If it is, the sensor is most likely OK.

It is WAY more likely you have regen troubles and a plugged DPF. You're going to need a better scanner to diagnose this.  At some point you're going to have to command a regen and watch the data to see what's going on.  Regen History will tell you what's going on.  Having HD Standard Datsa is not going to cut it, unless you get lucky...which happens to all of us sometimes, thankfully!

Joe

[tonybullitt]

Thanks, back where I was before need better tool to really diag it.

[tonybullitt]

Ok that's what I was afraid of. I found on quickserve where to convert the codes.

[tonybullitt]

He took the truck in to different place then before see what happens

[tonybullitt]

Sounds like they replaced the egr cooler (partially restricted) replacing all egt sensors. Sent dpf out for cleaning and are inspecting DOC. He would buy a scan tool that will work on this to bring with truck to me if reasonable priced and does all we need it to. Any suggestions?