DPF and white smoke

[JohnLynn]

The 2138 pid posted by ExNissan shows the soot % which obviously goes down once a regen is happening, this combined with raised exhaust temperatures show that a genuine one is happening. This can be seen easily enough with scan gauge or torque pro, but is different to my observation that the % falls by roughly half without any increase in temperature, in other words a recalculation?
However on one of the graphs I have included the "DPNR/DPF rejuvenation status" which can be "standby" "ready" "operate" and "complete" you probably noticed that this does not move from standby before, during or after. Luke on the Fortuner forum has seen this change when a forced or manual burn is carried out so maybe that is what it is meant to show. I hoped by including it that someone would tell us.

[LeadWings]

Sorry I didn't realise that the forum doesn't seem to allow the pictures to be magnified. I am pleased that someone is actually interested!!

John, thanks for posting/linking to the other forum - I was going to ask you to post better images also but those are fine. Very interesting - it really is a complicated system, pit we have to have it.

Have you found a OBD code for when the car is doing a regen?

[JohnLynn]

Sorry I didn't realise that the forum doesn't seem to allow the pictures to be magnified. I am pleased that someone is actually interested!!
I posted the same ones on the Fortuner forum here https://www.fortunerforum.com.au/for...dpf-myth/page6 and at least on my PC using Firefox they can be clicked on to enlarge to a sensible size to see them.
Please let me know if you can see them OK on the link if not I will upload them to a photo sharing website.
I would also like to know wtf is going on with the recalculation after a regeneration. After this burn my soot % quickly increased to 78% then fell almost in half before slowly increasing again. It behaves like this ever single time.
I don't think there is anything wrong with my Prado, it had covered nearly 400 Km between regens and they are over with quickly. It is just why this recalculation is done that is doing my head in. Especially as my dealer service manager says it doesn't happen.

[120D4D]

I have recorded a regeneration while mainly travelling at around 100Kms/hr on the freeway.
I know that cuda who originally started this thread is going to do the same once his car has reached 100%, he has an auto so it will be interesting to see if there is any difference.
One screen shot shows main and after timing, and DPF temperature set against the soot %
You can see that once 100% is reached the timing is retarded but it seems that after the soot falls back to 98% the main timing is restored to more or less what is was before the regeneration.
Another screen shot shows the 5th injector on/off, this is "on" nowhere near as much as I had previously expected.
The last screen shot shows the injection volume which is higher even when the timing seems restored to normal. Unfortunately the last third of these graphs were in mixed driving having left the freeway so are pretty meaningless apart from the very end where the car was left running at fast idle 1200 rpm as this is a manual, you can see the B1S2 temperature climb even more.
If anyone can interpret the graphs better than me or would like any other parameters uploaded please just say. This was taken from a recording of all engine data list parameters which slows down the rate but I didn't want to miss anything.

Any chance of re-posting these in a larger size John, I'm squinting so hard I nearly pulled a muscle!

[Atherton]

I'm guessing some of you have never seen where the oem intake takes its air from? It's in between the firewall and body next to the wheel arch. If you think that the air is cooler and cleaner from there then I don't know what to tell you.

Im not saying there is a huge difference but there would be a small one.

A snorkle is literally just a raised air intake, if you're following a convoy blowing up dust on the road it's not going to make any difference where it is, the only advantage of a snorkle in that situation is that you could probably put a sock on it. As for cooler- perhaps, but I'm honestly dubious as to if it'd actually make a difference large enough to be measured in any qualtifiable way- our cars have intercoolers for that very reason.

As for it "Ramming" air into the motor, that doesn't make sense on a turbocharged engine- The turbo is already punching air into the motor at ~12 psi (on the D4D anyway, not sure about the new ones), how is a "ram head" going to increase that pressure? As for running "richer"- It can't, aside from any other reason (and there are quite a few) the computer controls the air/ fuel mixture precisely to where it needs to be.

[Micko2005]

Just had the DPF replaced on 2016 Gxl auto (20,000k), early days but the fuel economy has improved. The question is what is different from the old DPF to the new one, will it be the same issue in another 20,000ks

[JohnLynn]

I have recorded a regeneration while mainly travelling at around 100Kms/hr on the freeway.
I know that cuda who originally started this thread is going to do the same once his car has reached 100%, he has an auto so it will be interesting to see if there is any difference.
One screen shot shows main and after timing, and DPF temperature set against the soot %
You can see that once 100% is reached the timing is retarded but it seems that after the soot falls back to 98% the main timing is restored to more or less what is was before the regeneration.
Another screen shot shows the 5th injector on/off, this is "on" nowhere near as much as I had previously expected.
The last screen shot shows the injection volume which is higher even when the timing seems restored to normal. Unfortunately the last third of these graphs were in mixed driving having left the freeway so are pretty meaningless apart from the very end where the car was left running at fast idle 1200 rpm as this is a manual, you can see the B1S2 temperature climb even more.
If anyone can interpret the graphs better than me or would like any other parameters uploaded please just say. This was taken from a recording of all engine data list parameters which slows down the rate but I didn't want to miss anything.

[prado R83D]

I'm guessing some of you have never seen where the oem intake takes its air from? It's in between the firewall and body next to the wheel arch. If you think that the air is cooler and cleaner from there then I don't know what to tell you.

Im not saying there is a huge difference but there would be a small one.

[JohnLynn]

My thoughts as well but too polite to mention them, as for making it "run richer"! whoops sorry I have said it now.

[Falco80]

It's a turbocharged engine, how is a snorkel going to do anything? You may get a "ram" effect with a naturally aspirated engine, but not on a 2.8 TD prado engine.

[LeadWings]

It makes me wonder what effect a snorkel has in relation to the exhaust issues. A snorkel would force more fresh air into the engine, makes it run richer and whether this would have either a positive or negative effect on the DPF.

With the modern sophistication in the engines, I think it would compensate - the sensors are measuring air mass flow, temperature etc in the intake, engine conditions such as RPM etc and using it to calculate density etc and basing fuel injection etc on that so would be compensating. And as CamJam says, with all the bends etc I'm not sure it would increase the feed pressure.

[CamJam]

It makes me wonder what effect a snorkel has in relation to the exhaust issues. A snorkel would force more fresh air into the engine, makes it run richer and whether this would have either a positive or negative effect on the DPF.

I've got a snorkel, I doubt it makes a difference. The reason I say that is that this 'ram air' effect is a bit of a furphy going by physics. The airflow coming in has to do about a 130 degree turn to go down the pipe. So it's lost its momentum. It then bends 90 degrees at least three times (into side flank, along side flank, then again into the engine bay). It then turns 90 degrees upwards and hits a paper filter AND a metal plate that distributes the air more evenly in the Prado. It then makes its way into the pipe heading off to the engine. That's a lot of twists, bends, plates and turns that kill any 'ram air' effect. The air at the top of the snorkel will follow the path of least resistance - once that airflow is clogged up from all this turning and twisting it will create a relatively sedate bit of air at the intake and only allow in what it needs in order to feed the engine (call it akin to the Boundary layer effect), it will simply go around the head. So it's no better or worse than the standard air intake (except it's sealed and higher to prevent water ingress). I think the engine just gets whatever it needs.

It's like the 'it's higher so the air is cleaner' thing. My view is that if you're first in convoy or on your own, then that won't matter - you get clean air. If you're in car number 2 or more, then chances are you are keeping a good distance of around 100m or more behind the car in front - and so all that dust from them will, by the time you get to it, come up past snorkel level anyway... I've done a lot of dusty driving solo and in convoy and I haven't yet seen a benefit of it (other than its intended purpose - the water crossings).

[tonykarter15]

It makes me wonder what effect a snorkel has in relation to the exhaust issues. A snorkel would force more fresh air into the engine, makes it run richer and whether this would have either a positive or negative effect on the DPF.

[CamJam]

I am sure you will put me right if I have got this wrong but Adblue is to stop nitrogen oxides in the exhaust and nothing to do with the DPF which is for filtering soot and tiny particles.
AFAIK Australian vehicles only have to conform to Euro 5 at present, the Adblue is necessary to conform to Euro 6 so not presently required but I think I have read that the wiring is already in our Prados.
Perhaps I worry too much about the DPF issue as I regularly monitor the soot %, DPF differential pressure and temperature and feel I would have very advanced warning if things were not working as they should.
Whether or not everyone should buy a cheap BT adapter and look at an android device to check is another matter.

True - it's necessary for Euro6 compliance (unless you have some magical fantastic DPF and another piece of tech - it's not written in "you must have xyz fitted" but rather you have to meet emissions which, at this stage, are mainly met through DPF/ EGR/ AdBlue for Euro6) and we're at Euro5 at the moment. I just think a limp home mode is not only more convenient, but far safer should it fail. It's not as if someone will think "Nah, can't spend money on getting the DPF fixed or paying $10 for AdBlue - I'll just trot around at 30km/h"...

EDIT: And yep - has nothing to do with the DPF. The course of history generally had the DPF first, then the AdBlue as requirements got tighter.

[JohnLynn]

I am sure you will put me right if I have got this wrong but Adblue is to stop nitrogen oxides in the exhaust and nothing to do with the DPF which is for filtering soot and tiny particles.
AFAIK Australian vehicles only have to conform to Euro 5 at present, the Adblue is necessary to conform to Euro 6 so not presently required but I think I have read that the wiring is already in our Prados.
Perhaps I worry too much about the DPF issue as I regularly monitor the soot %, DPF differential pressure and temperature and feel I would have very advanced warning if things were not working as they should.
Whether or not everyone should buy a cheap BT adapter and look at an android device to check is another matter.