Emissions Faults (Technical) - Pls Advise

[Quantum]

I've been struggling for two months with my DEF system, and now the DFP is not regenning but needs to.

This is a 2016 Cat 299D2 XHP (DX200946) which I've just rebuilt from total burnout. Everything works except for this and I've done all calibrations. The symptom starts on engine start with this:

... and ~45 minutes later comes up with this:

So I thought it's a DEF circulation problem. I flushed the injector ($1,200) through the nipples overnight, and then I attached the garden hose to the injector port (90psi), applied 12v and white stuff vomited out the nipples. I can hear the solenoid clicking as I apply and remove 12v. So I let that flush overnight. Didn't help.

I suspected the DEF pump ($2,400) and took that apart examining the ports, gears, filter chamber, but no blockage. I reinstalled the pump and ran a clear tube from the DEF tank to the pump. It did suck for 1.5 minutes, but then reversed as if clearing. I put pins in one of the pump's 3 phase wires and to the ground. 2.8 vAC as expected, which went away after 1.5 minutes then came back, presumably in reverse.

I feel sure that fluid is getting circulated, although it doesn't look like very much volume or pressure, basically a trickle, although the injector port is quite small. I put the plastic tube on the pump output and it trickles just enough to not break into drops. I've removed the DEF filter and no change. I've replaced the filter and space-taker-upper plug with new. I took the injector off the manifold and wrapped it in a baggie, started the engine, and nothing came out.

Here's what ET says:

Huh? DEF Pressure negative? (Although Max 21.7) Must be in the clear cycle, right?

DEF Pressure now is 1.7psi?

So that's a problem.

Now I've run the engine so long struggling with this, that DPF needs to regen.

... but it's inhibited. Inhibited by what? Nothing? Could it know that it's not getting DEF? Why should oxides of nitrogen have anything to do with carbon build-up?

Park it in safe location and then what? Wave my hands in the air like I just don't care? It already is parked in a safe location.

I try to do a manual regen and it claims success in starting, but it never actually starts. I've tried with throttle at zero, and at max, waiting 15 minutes for each but status is always not in regen cycle, and Inhibited.

The only other abnormality in the whole system is the fuel pump is showing to be recalibrating. I'd initiated this two weeks ago and interrupted it because of the DPF, but it's still showing active. I tried to calibrate it again but nothing seems to be happening.

 

[Tags]

The engine temperature needs to be high to start a regen. Like set it at full throttle and walk away so it gets up to temperature, but if you can't operate the machine I'm not sure you'll actually get it hot enough

 

[Cmark]

The system needs to see approx 50psi DEF. Have you checked the screen on the pickup tube in the tank?

 

[funwithfuel]

With SCR pulling you into derate, doesn't look like you'll ever get into regen. Solve SCR first. By your descriptions, it looks like either you have crystalization in the line leading up to the injector or your pump is failed.
I yield to CMark, he beat me to the post.

 

[Quantum]

Gee, 50psi sounds alot more plausible for this. I've replaced the screen on the pickup tube. And there was dirt in the tank so I rinsed and vacuumed it clean inside in an attempt to fix this.

At the same time I disconnected the lines from tank to pump and pump to injector, and blew them both out with the garden hose. I saw the tank-to-pump line blow clear but I'm not entirely convinced the pump-to-injector line blew clear as there wasn't much water in the engine bay. And I blew out the intake and return stainless tank lines. Two of the three ($240ea) DEF lines are new.

Then when I reassembled I left the pump outlet disconnected and it only came out a trickle. I thought maybe it needs a prime so I reversed my shop-vac and blew into the DEF fill port to pressurize the system, but no improvement after a good bit.

So I opened up the pump and exposed the gears and ran it, and they are spinning like sixty. And when I turn off the key I hear what sounds like the pump still running and it seems fine.

Then I bypassed the tank-to-pump line with 1/2" clear tubing so I could see what's going on. It draws slowly as a trickle for about 1.5 minutes, then reverses. I wanted to put my own voltage directly on the pump to test it with water but I found that it's a 3-phase DC pump so I can't possibly simulate that (sawtooth?) signal.

But when I take out the DEF injector and run it into a baggie, and there's no liquid, that is bad. And the pump output is inexplicably bad.

I don't understand how the pump can not be moving liquid, yet be spinning like it does. Maybe I should disconnect the lines directly on the pump housing and put my own plastic tubes on it to eliminate everything but the pump itself?

 

[funwithfuel]

Your DEF pump should provide adequate pressure and flow during operation, once shut down it should go into purge or backflow depending on how CAT configured the system.
You should hear a click followed by continued pump operation. The click was the divert or backflow valve opening. The pump running is now drawing the DEF from the nozzle and lines back into the storage tank. You may hear the injector nozzle click open to prevent vacuum or voids.
All DEF lines are electrically heated. Key on , they should warm up to "thaw" any remnants in the lines. The tank will be heated either with warm engine coolant through a thermostatic valve or electric heating strips in the tank.
When the pump and engine are running, all the lines should be warm. If you place the injector in a bucket, you should see fine mist . Dribbling indicates obstructions, clogged filter or weak pump. There should be a serviceable filter in the pump assembly.

Some important things to consider when messing with DEF and SCR. Nothing but vinyl and stainless steel for tools. All water should be de ionized purified drinking water. No tap water. No iron, chrome or steel tools. Here's the rub... the inside of the catalyst or decomposition chamber is coated with a relatively fragile material, its stable in exhaust flow and urea injection, it will not survive iron contamination. Any particulate iron gets trapped and begins to slowly chip away at your coating. Your catalyst efficiency drops , more and more til it can't does enough to convert.

I hope this helps a little in trying to get this solved. That said stage 3 derate which I believe is what your second image showed, will require a recommission by cat to continue. Federal anti tampering laws, aren't they nice.

 

[Quantum]

Your DEF pump should provide adequate pressure and flow during operation, once shut down it should go into purge or backflow depending on how CAT configured the system.
You should hear a click followed by continued pump operation. The click was the divert or backflow valve opening. The pump running is now drawing the DEF from the nozzle and lines back into the storage tank. You may hear the injector nozzle click open to prevent vacuum or voids.

There's no reversal valve, only the direct connections. It appears that reversal is done by reversing the pump electronically. No way to hear any clicks while the engine is running; I do hear what seems to be the DEF pump when I only turn the key on and don't start.

All DEF lines are electrically heated. Key on , they should warm up to "thaw" any remnants in the lines. The tank will be heated either with warm engine coolant through a thermostatic valve or electric heating strips in the tank.
When the pump and engine are running, all the lines should be warm. If you place the injector in a bucket, you should see fine mist . Dribbling indicates obstructions, clogged filter or weak pump. There should be a serviceable filter in the pump assembly.

Hadn't thought to check for warmth, although I did ensure that the fluid in the tank was not frozen. Indeed there are heating strips in the pump, and the tank is warmed by coolant.

No way to put the injector in a bucket as it's way up in the corner of the engine bay, but tying a baggie over it I find no output as noted above. There is a filter in the pump and it's new.

Some important things to consider when messing with DEF and SCR. Nothing but vinyl and stainless steel for tools. All water should be de ionized purified drinking water. No tap water. No iron, chrome or steel tools. Here's the rub... the inside of the catalyst or decomposition chamber is coated with a relatively fragile material, its stable in exhaust flow and urea injection, it will not survive iron contamination. Any particulate iron gets trapped and begins to slowly chip away at your coating. Your catalyst efficiency drops , more and more til it can't does enough to convert.

Oh well, too late for that, I've used hose water to purge everything. But the exposure shouldn't have been long enough to do damage.

I hope this helps a little in trying to get this solved. That said stage 3 derate which I believe is what your second image showed, will require a recommission by cat to continue. Federal anti tampering laws, aren't they nice.

Ah, they're not serious. When the DPF gets clogged I'll decompose the whole top of the engine bay to remove, and wire-brush and blow out the DPF myself. Notice that it does say it has 100% soot load, but that backpressure is zero. I'm trying to run it as little as possible to try and solve this DEF problem, even as I see no relation to the DPF problem.

 

[dtcohen]

The "engine de-rate - protect mode against cold temperature" is a feature that is built in to protect the turbo. All it does is limit the engine speed until the engine has warmed up a little bit. It has nothing to do with the DPF or SCR system.

 

[dtcohen]

A piece of cardboard placed between the grill and the cooling pack will block air flow through the cooler and can help to get the temperature up high enough to perform a regen.

 

[funwithfuel]

Not to beat a dead horse, if you are in level 3 SCR fault, it will probably not allow you to enter regeneration.

 

[92U 3406]

The reason you see the SCR fault after about 45 minutes is that the system is allowed to run that long without injecting DEF into the SCR catalyst to ensure the DEF has sufficiently thawed in cold weather. Are you able to view DEF tank temperatures?

 

[Cmark]

Near the beginning of this thread I said that the system needs to see a DEF pressure of approx 50psi, and that is the key. If, for whatever reason it doesn't see that pressure within about 90 seconds of running then it interprets it as a frozen DEF event and goes into the thaw cycle. If it still can't see the required pressure after 45min of running the thaw cycle then it sets the event code.

 

[Quantum]

Ok, it's good to know that the initial de-rate message is normal. I don't understand why SCR is linked to DPF regen, as one is oxides of nitrogen and the other is carbon in the filter, but maybe it's just the way they've done the firmware.

After the engine has run a while the DEF temp is usually 50F. One cold day (20's) I checked and the DEF was not frozen, which I was surprised at, but it still would not pump adequately.

And Cmark your remarks are why I'm moving on to my next tests. We've had 6" of snow here (record-breaker) so I've been paralyzed, but it's melting now. I know that there's free flow from the tank to the pump, but apparently not out of the pump since it's only been a trickle.

So I'm going to open up the DEF box, lift up the pump, remove its connections, and test it with plastic tubing in and out. It had better give full flow then. If so, I'll work my way out from there. If not I have to try and find a used pump somewhere.

All I've found so far is melted ones from when ppl set their machines on fire for insurance.https://www.heavyequipmentforums.com/members/cmark.7997/

 

[Quantum]

I opened up the DEF pump box and extracted the pump itself. I connected clear plastic lines to in and out and ran it with water.

The water moves and flows about like I'd expect it for gears of this size and speed. I partially plug the output and it develops pretty decent pressure to make a fine spray. Looks to me like it's Ok.

What's more is it did not time out after 1.5 minutes as it had before! Why? It has going to it four wires, being the three phases and ground. So there's no speed or pressure sensor built into it, unless current is measured to determine load.

Next I'll reinstall the pump into the box and connect only the stock inlet to it. This will test everything from the pump to the tank.

 

[Quantum]

Putting the DEF pump box completely back together and testing its output, it seems fine for both volume and (restrained) pressure. It is good considering the small diameter of the injector input.

BUT it cuts off after 1.5 minutes, even as I restrain output (increasing back-pressure), and then reverses flow. The only thing that seems like pressure measurement is inside the pump box right before the outlet.

I'm assuming that the reason it can normally build up pressure in the line is there must be a restricter at the injector's outlet tube. So pressure builds up for the injector, without being sent straight back into the tank.

Well, I guess my next test is to put a baggie around the injector to see if anything comes out. I doubt there will, and so I'll be quite confused. I've manually actuated it and flushed it overnight successfully.

 

[Cmark]

So are you now seeing 50psi in ET?

 

[Quantum]

I don't know, but it's difficult, almost impossible, for me to stop it up completely.

If I have nothing coming out of the injector, I don't know what else to do but take the machine to the stealership.

 

[Cmark]

It shouldn't inject all the time. At start up it just circulates DEF through the injector and back to tank. The internal resistance to flow in the injector should give the appx. 50psi.

I thought you had ET?

 

[partsandservice]

Once again you are likely locked out unless you have factory passwords. When the service truck shows up , tech will have to email for the passwords , he will not have them in his et. What SCR has to do with DPF, is they are both components of the exhaust treatment system .

 

[BigWrench55]

The DEF system at startup pumps the fluid out and does a pressure check on the system. If it detects a leak (low pressure) it will pump it back to the tank. At the moment I can't remember where pressure is read. I want to say in the pump but not for certain. You will need to look in SIS to find out for sure. If you can, put the DEF system back together and pull vacuum on it. If you get a vacuum then you have a pressure sensor problem. If there are faults with the DEF or the SCR it will not allow you to regen manually or otherwise. I hope this will get you pointed in the right direction.