Fuel in oil, white smoke. Injectors???

[Jazz]

I should have mentioned that I have never noticed the DPF light come up on the dash, either before the DPf was removed or after.

I just ran the scan gauge for codes and it says no codes, but also says "not ready" on the second line. According to the scan gauge manual this indicates the vehicle may still be running a test or cycle of some type. Would this be heading towards confirming we are in a regen cycle? or is it common for the "not ready" message to pop up?

 

[Teleman191]

I know I'm a newbie here, but I heard/read somewhere that there is a software update for yd25 engines across the board, but Nissan isn't calling owners to get there vehicles in. (Not a recall issue) but the update is directly related to the amount if smoke a yd25 creates. I know diesels blow smoke but there are a lot of complaints from people saying there is too much smoke. I wonder if the computer update along new pressure sensors would fix the issue. ???

 

[Old.Tony]

There might be a software update and I bet it does something towards the higher fuel consumption some of us have been experiencing - particularly the Thai-built D40s (KC and RX models).

It really does sound like a regen is happening. You don't get to see the DPF light - I know my DPF light works, after a recent post where someone asked about this specific issue, I checked that my DPF light does come on during the self-tests when the ignition turns on. However, I have never seen my DPF light come on during driving. Not in the city, not on forest trails, climbing mountains, fording rivers or driving through central Australia. So this really is starting to look like a sensor failure.

The unfortunate thing with the sensors is that you can't fool the system. They need to sense SOME pressure, so disconnecting them is not an option. I don't know what they're worth but I bet that because they're essential to the operation of the vehicle, Nissan will price them accordingly (not because it's Nissan, but because ALL of them do it).

 

[Jazz]

There might be a software update and I bet it does something towards the higher fuel consumption some of us have been experiencing - particularly the Thai-built D40s (KC and RX models).

It really does sound like a regen is happening. You don't get to see the DPF light - I know my DPF light works, after a recent post where someone asked about this specific issue, I checked that my DPF light does come on during the self-tests when the ignition turns on. However, I have never seen my DPF light come on during driving. Not in the city, not on forest trails, climbing mountains, fording rivers or driving through central Australia. So this really is starting to look like a sensor failure.

The unfortunate thing with the sensors is that you can't fool the system. They need to sense SOME pressure, so disconnecting them is not an option. I don't know what they're worth but I bet that because they're essential to the operation of the vehicle, Nissan will price them accordingly (not because it's Nissan, but because ALL of them do it).

I think your right, the way the smoke comes on and off, as if flicking a switch, does sound like a regen issue.
This is where i had my doubts when speaking to the mechanic about it being a constant oil/fuel leak. As I couldnt understand how the vehicle seems fine and will idle, hot or cold and have no smoke, then sometimes blow a smokescreen out for a few minutes.

 

[Jazz]

Latest news....

After testing the mechanic reckons the leak is not in the spill line. So the most likely cause is the fuel pump seal, but cant really confirm this until removing the pump.

When i spoke to him about the occasional white smoke, he seemed to agree it sounds like DPF regen that cant be completed due to the DPF being removed. He said he can try to manualy clear this, I'm not sure how.

I was talking to him about dodgy pressure sensors triggering the regen and he is going to check them. He said he thinks the regen can also be trigered after a set number of km. I always thought it only came on due to the pressure differential across the sensors? If this is the case its only a matter of time (or km) before the thing gets stuck in the regen cycle again.

Anyone heard of the regen being triggered by km rather than the sensors?

 

[Old.Tony]

The regen is supposed to happen when there's a pressure differential between the two pressure sensors. In normal use, that will happen somewhere between every 100-300km of driving (that's normal, not hard, towing etc).

The only problem with resetting it is that if it senses a pressure differential it will just start it up again so the effort was wasted. The return signal from the two sensors has to be the same (same voltage on the return lines) so it should be easy to determine if the sensors are now mismatched.

If the sensors are reporting differently it could be one faulty sensor or a sensor could be blocked.

If the sensors aren't mismatched, letting it go at 1600rpm+ for 15mins or so might be enough to clear it - if the mechanic can't convince the ECM otherwise. I don't think a fuel pump learning reset will do the job - from past anecdotes, once the ECM is convinced it needs to do a regen, it becomes quite determined.

 

[Jazz]

The regen is supposed to happen when there's a pressure differential between the two pressure sensors. In normal use, that will happen somewhere between every 100-300km of driving (that's normal, not hard, towing etc).

The only problem with resetting it is that if it senses a pressure differential it will just start it up again so the effort was wasted. The return signal from the two sensors has to be the same (same voltage on the return lines) so it should be easy to determine if the sensors are now mismatched.

If the sensors are reporting differently it could be one faulty sensor or a sensor could be blocked.

If the sensors aren't mismatched, letting it go at 1600rpm+ for 15mins or so might be enough to clear it - if the mechanic can't convince the ECM otherwise. I don't think a fuel pump learning reset will do the job - from past anecdotes, once the ECM is convinced it needs to do a regen, it becomes quite determined.

Picked the vehicle up this afternoon. No smoke at the moment. The mechanic ran it on the dyno and did a forced burn. He said it ran for a good 40 minutes until it stopped the burn. I thought he was joking!
The recipt of work done states "Force dpf burn via scan tool and check dpf pressure and temp sensor operation, road tested and found ok."
He also said the injectors need replacing.

So its fixed for now.....

He is certain that a burn cycle will again occur after a certain number of km, not necesarily due to differential pressure. He also said he's sure theres no way to get the ECU to stop the burn until it wants to stop.

I'm really not sure what to do with it? I cant take it back to the mechanic every time it gets stuck on a regen cycle.

 

[Old.Tony]

I'd drive it for a few days and see what it does. Forced regens are generally only needed when the normal regens aren't successful and that still points at the sensors.

Let's see what a bit of driving does.

 

[Jazz]

Vehicle started smoking again at around the 300km mark.

Went for a 40km drive on the highway and its back to normal. Not sure at what point the smoke stopped, just know it was gone after 40km.

I am now monitoring the km's to see if i can predict when it happens. If its regularly coming on at 300km I can at least get it to the workshop before it triggers so they can see it while the fault is occuring.

I have also found someone who is confident they can delete the DPF cycle from the program. But i need to confirm this is the problem before throwing more money at the issue.

 

[Bvandermaat]

If it were me I would stick the two sensors in a pipe at either end and put a tyre valve in the center. Then pressurize it to what ever the standard exhaust pressure is and the DPF regen should never run again.

Or at least that is how it would work in my head.

 

[Jazz]

If it were me I would stick the two sensors in a pipe at either end and put a tyre valve in the center. Then pressurize it to what ever the standard exhaust pressure is and the DPF regen should never run again.

Or at least that is how it would work in my head.

Not a bad theory....

But i think the regen is being triggered by km not pressure.

My understanding is that the sensors only show the pressure differential between them, so the absolute pressure doesnt matter.

 

[Old.Tony]

Sensors really just return a voltage based on a voltage input - 5V is sent down, and between 0V and 5V is expected on the return. The value determines the pressure measured. A fault in the sensor would result in a variation in return voltage which would be interpreted as a variance in pressure (obviously).

I wonder if that's the problem? If it is, then there's a possible solution. The ECM will look to see if sensor B (the one that should be behind the DPF matrix) is returning a lower value than sensor A and the program will be simply this:

if (sensor_b_value < sensor_a_value) then { initiate_dpf_regeneration_cycle; }

There's an easy way to fool this: swap the sensors over. Sensor B will always have a value HIGHER than sensor A (until it too fails, and then they're both equal) so it will not meet the criterion for the burn.

It might not be like that - but it's a bloody cheap thing to try and shouldn't hurt a thing. Swap 'em over and take the car out for a run where rpm > 1600 for 10mins+.

 

[Jazz]

Sensors really just return a voltage based on a voltage input - 5V is sent down, and between 0V and 5V is expected on the return. The value determines the pressure measured. A fault in the sensor would result in a variation in return voltage which would be interpreted as a variance in pressure (obviously).

I wonder if that's the problem? If it is, then there's a possible solution. The ECM will look to see if sensor B (the one that should be behind the DPF matrix) is returning a lower value than sensor A and the program will be simply this:

if (sensor_b_value < sensor_a_value) then { initiate_dpf_regeneration_cycle; }

There's an easy way to fool this: swap the sensors over. Sensor B will always have a value HIGHER than sensor A (until it too fails, and then they're both equal) so it will not meet the criterion for the burn.

It might not be like that - but it's a bloody cheap thing to try and shouldn't hurt a thing. Swap 'em over and take the car out for a run where rpm > 1600 for 10mins+.

Brilliant in its simplicity Tony!!

Unless the differential sensor just measures the differance between the two regardless of which one is higher? not sure if that makes sense?

Ive ordered an OBD log device to collect data, cant hurt to have more info I guess.

 

[Old.Tony]

Brilliant in its simplicity Tony!!

Unless the differential sensor just measures the differance between the two regardless of which one is higher? not sure if that makes sense?

Ive ordered an OBD log device to collect data, cant hurt to have more info I guess.

From a computational standpoint, to measure the DIFFERENCE and then compare it you'd have to take the ABS() of the difference.

If there's no actual need to do that, I'd wonder if the programmer would bother. I guess we'll find out if the sensor IS faulty and seeing the result of swapping them around!

 

[Jazz]

Well the smoke has started again.

The speedo shows about 270 since the last smoke session.

Now I cleared the last one out by doing a 40 km drive. I dont know at what stage in that drive the computer decided it had done enough and reset the DPF burn. So if we guess it happened about the 15minute/20km mark it does seem to show that the km based DPF burn is happening at about 300km (270+20).

The previous time it happened was at about 300km, the time before that was at 900km but this period featured a 520 km round trip on the highway so it may have done two burns, at 300 and 600 without me knowing it.

 

[Jazz]

10km drive @ 80-100kmh and the smoke has cleared.

290km to go till the next episode.

 

[Boosted]

Do you baby the car around when you drive?

 

[Jazz]

Do you baby the car around when you drive?

No i wouldnt say so, would be about standard I reckon.

 

[Old.Tony]

I'd wonder why the ECM is still thinking that a regen is needed. Our cars (fitted with a DPF) should do a short regen burn every 100 to 300km and that's what you might be seeing. It probably shouldn't be seen as a large plume (I've never noticed mine but my DPF is still intact). I wonder if this is related to the fuel-in-oil problem as well, amplifying the issue?

Here's another thing to try - one method is legal, the other is not. The legal way (and recommended) - fit a catch can.

The illegal (and cheap) way is to remove the clamp from the PCV hose where it connects to the air intake and route it down the side away from the turbocharger. It most definitely will release oil (even if everything is in good working order) so don't aim it at your tyres and don't do it for too long, max 300km. See if the clouds of smoke lessen.