Hi guys any help appreciated on this. We have an l90h shovel on 10500 hours recently started wanting parked regens daily. Will complete them if on the button or forced. Only fault it had was faulty pressure sensor before turbo that has now been replaced. Dpf differential pressure is high compared to reference values. Should be at 3.2kpa on full stall but does infact rise to 9.0kpa. dpf differential Sensor checks out and dpf was replaced at roughly 7.5k hours So not that old and in my head unlikely to be blocked. Yesterday I checked egr differential sensors and cleaned out the venturi holes. Cleaned out map sensor on intake. Tested egr valve. Tested both back pressure sensors and differential sensor. I'll put my stall test results below Dpf sensor reading 1.7 at start rising to 2.4 midway. Exhaust temps- 500- 567 before dpf 540 after After regen. Dpf pressure in spec at idle but 6kpa full stall straight after forced regen. Egr opening 5 percent full convertor stall Egr differential pressure 11 full stall Egr gas flow 3.25 Egr temp sensor 116 degrees c full stall Exhaust pressure before turbo - 239kpa dpf pressure full stall 8.9 Dpf outlet pressure - 7.2kpa full stall everything seems to be in spec apart from dpf pressure and egr opening percent should be between 9-15%. I'm curious if it's not quite getting to temp and should be in the 600 degree range? And therefor not burning enough soot to bring pressures down? Anyone have any thoughts? Thanks.
Have you looked at the health of the engine?
Hi, Can you elaborate?
Well if the engine is having issues and making lots of smoke or burning oil you won't see it because the DPF catches the excess particulates. You'll see more frequent regens but it's because the engine is the problem, not the DPF system.
Ah I get you. Engine is well serviced with no issues. No smoke or oil loss.
100% agreed. Unfasten the pipe feeding DPF and diect safely away. Snap the throttle a few times. See if you get thick billowy smoke, blue, grey, white. Try n capture on video and post to YouTube. 2500 hrs on a DPF is only half life.
Thanks. I assume your talking about the small diameter pipe feeding the pressure sensor?
No the corrugated exhaust pipe off the turbo that feeds the DOC. Should be like 3, 3½ inches in diameter.
Will try tomorrow! Thanks.
If all your sensor readings are correct or at least plausible, then you kinda have to look at the unseen as 92U 3406 mentioned. What does your ash accumulation read? How quickly does soot accumulate post regen? Like % per minute or per hour? Are we absolutely sure that there is no air intrusion on either end of delta sensor?
Make sure you have no sticky tar on the cold side of the EGR . The H series are pretty robust, but ya gotta make sure.
I am curious why egr is only opening 6 percent on stall. But it will actuate to 100 percent on a test. Do you happen to know the correct regeneration temps before and after dpf?
There's no constant. It's a slow progressive increase up to 1250°F iirc. It's metered and controlled to prevent cracking the filter media.
Interesting. This is only reaching max 1052 degrees Fahrenheit
That doesn't seem adequate, but if it says your soot is dropping to 0, it's a completed regen. It sounds like you have some level of diagnostic software. See if it will allow a throttle control motor test. Usually they will show errors when faulty but they do get lazy. If you remove the inlet bellows, you should be able to push the butterfly open with your finger. Release it quickly, it should almost bounce shut. If it doesn't, perform the exercise test in techtool. See if it passes. As for EGR opening, it's just trying to maintain a ppm value before SCR and anything not addressed by EGR will be corrected out with DEF through the SCR.
Yes using jaltest and an old version of prosis but it is limited and doesn't have throttle valve testing feature, but will try your suggestion manually. I believe the L90s are due injectors at 10000 hours. nothing points to them as being being faulty just yet ( I'll do this smoke test with exhaust off first) but would this be a reasonable place to look next if all else is well.
Oh yeah, the crankcase breather. Make sure it's not plugged and that the oil side returns to sump. Are you building good boost? Should be close to 1.5 bar full throttle/ full load. Full load being APS in manual or service, 4th gear selected in drive against convertor with hydraulics over relief. 10 seconds load, 15 seconds off to avoid smoking the trans oil. Good luck.
You really need to clear up your data. A number of you descriptions of sensor values are not correct. It would be better if you included the sensor number for each value you post. You are mainly concerned with Exhaust temps, DPF differential pressure, pressure before the SCR, inlet manifold pressure, exhaust gas pressure before the turbo, EGR temp and differential pressure, as well as Nox before and after the SCR. You have no mention of your Nox numbers so we don't know hat kind of conversion you are getting. This will more often cause frequent regeneration complaints. From what I can gather your EGR differential pressure is much too low at full stall, it should be from 11-17kPa at full converter stall. This indicates insufficient EGR flow at full stall, usually an indication of a plugged EGR cooler, although the EGR valve is not opening as fully as it should. It would be good to know the Nox before SCR numbers. The DPF differential pressure is too high indicating an issue with the DPF either plugged or melted. Ash does not increase differential pressure that much as it allows exhaust gas through it. Are measuring temps in C of F? If C temps are actually higher than they should be. They should be from 280-360C 536-680F with the before DOC being the highest and the after SCR being the lowest As @funwithfuel said definitely disconnect the exhaust at the DOC inlet and observe the exhaust.
Thanks Ben. I will include numbers in the future. Can you tell me what numbers are not correct so I can have a look please. I'm only going on reference values I have to hand that I'm assuming are correct. With egr differential pressure, I do have 11kpa on a stall test. Temps are in Celsius and your information is interesting. I tested our other l90h today on a parked regen and temps are exactly the same. So I'll look into that. Thanks.
It seems you are comparing values during a regen and at stall. You need to separate this 2 sessions. During a regen temps are the main value you need to look at. If anything is off significantly it will most likely trigger an error and cancel the regen. During converter stall you need the other sensor values. One thing you mention is DPF sensor. This needs to be clarified as there is no DPF sensor. It is best to include the component designation such as SExxxx, MOxxxx, or FXxxxx.
Oh and regeneration temps should be getting to 560-580C. This should be before DPF temp. So your temps are not bad.