407 very intermittent surging

[moizeau]

Thanks Elis, just realised my post above is talking cobblers, obviously typing whilst being excited about the possible fix. Yes I agree, but I shall leave it with the repaired pipework and see if it does it again. If it does, I'll stop, that should put the butterflies back to their natural position and clamp them.
Regarding my cobblers.....The top butterfly comes from the top of the IC and is normally open (ignition off) the bottom one (oily beast) disappears into the depths and is normally closed (ignition off). Has anyone got a pictorial view of where all these pipes come from and go to please. (Just to improve my understanding)
Cheers

[EDC5]

This should help:

So your bottom butterfly valve will only open when the intercooler is being bypassed. It is oily as all of the EGR filth from the inlet mnifold will seep downhill towards the lower butterfly valve.

[moizeau]

Thank you very much Elis now I can see where the hoses bypass. I have seen how much crap there is in the plenum on the 2.1td, and on your topic, was quite scary. So when it goes into regen it closes the top one to isolate the IC but (hopefully) because of the poor connection to the vacuum solenoid didn't manage to open the bottom one. Makes absolute logical sense. If not, block the pipes and run it like a C5.
Thanks again, I'll let you know how it goes. I'll know within a week

[moizeau]

Just checked the soot level - 40%. Going to Lyon and back tomorrow so I expect a passive regen on the motorway, but just in case I have made up a bit of blocked up hose that will slide onto the RHS vacuum solenoid that closes the butterfly that comes from the IC. That should mean that if for whatever reason the bypass doesn't open I can keep the IC supply open. I shall measure soot levels when I arrive, and then again when I get home. I guess that if I have to use my 'bodge' it may throw something up. Does anyone see a flaw in my plan? I know I could just remove the bypass but I'd prefer to have it running as intended. Mr Pug wouldn't go to the effort and expensive of an extra solenoid, butterfly and pipework just for a laugh........would he?

[MikeT]

Due to the additive, passive regens occur pretty much all the time, when the engine/exhaust is hot enough.
Active regens are further invoked by the ECU when risk of DPF clogging occurs which is when the double-butterfly is used to bypass the IC.

By blocking the vacuum feed, you may provoke a fault code (ie copy signal not matching commanded setting).
By keeping the IC flow open, it will also struggle to reach the higher exhaust temperature required, which may cause the ECU to abort the regen and/or keep trying until repeated failures become excessive and another fault code is logged, possibly throwing the engine into limp mode.

An interesting experiment all the same and I'd love to see the Particulate Filter Live Data when try it.

[moizeau]

Cheers Mike, when you say the PF live data? That would be the same screen as I read when the engine is off ..standard parameters?. It does keep showing the condition of regen as 'regenerating' all the time. That's from 2% up to , I think, 83, it just stays there? Will know more tomorrow.
Cheers again Mike, I'll get my son to run it in the car, though the battery is only good for a couple of hours.

[MikeT]

I'm more au fait with Lexia so if you're using PP or Diagbox Pete, it may be slightly different but yeah the tree will be something like - Global Test, then select Injection ECU, Live Data, Particulate Filter, Standard Parameters.
I use the "average distance between last 5 regens" calculation to determine when the next regen is likely due and then record the live data while it's occuring.
As before, it's a mystery why yours constantly reports "Regenerating" as soot load brought down to 2% is mission accomplished AFAIC.

[moizeau]

It's due tomorrow on the way, I'll plug in the way, can't do it on the way home, the wife's not as literate as my son! But will read again when I get home. I'll keep you up to date.
Cheers Mike

[EDC5]

Due to the additive, passive regens occur pretty much all the time, when the engine/exhaust is hot enough.
Active regens are further invoked by the ECU when risk of DPF clogging occurs which is when the double-butterfly is used to bypass the IC.

By blocking the vacuum feed, you may provoke a fault code (ie copy signal not matching commanded setting).
By keeping the IC flow open, it will also struggle to reach the higher exhaust temperature required, which may cause the ECU to abort the regen and/or keep trying until repeated failures become excessive and another fault code is logged, possibly throwing the engine into limp mode.

An interesting experiment all the same and I'd love to see the Particulate Filter Live Data when try it.

The butterfly valves on this engine don't have position copy sensors that are present on the later DW10C engine. Also, my engine doesn't have the double air doser, so it's importance for the regeneration cycle is probably overstated.

Does anyone see a flaw in my plan? I know I could just remove the bypass but I'd prefer to have it running as intended. Mr Pug wouldn't go to the effort and expensive of an extra solenoid, butterfly and pipework just for a laugh........would he?

Just make sure that the working flap cannot close by whatever means in order to test the theory.

Mr. Pug has been known to go overboard with features only to remove them at a later date so I wouldn't necessarily say that's true

[moizeau]

Update, Set off this morning, soot level was at 43%. Plugged the 'puter in once we got on the motorway and the soot levels gradually rose until they hit 63% and the cat downstream temp was just above 400...then the battery went flat. Arrived at Lyon, which was a journey of just over 200 miles, charged the 'puter and plugged in. Soot level 2%. So it did regen on the motorway (but it's done that before without misbehaving) but unfortunately I missed it on the screen. Just got back and it now reads 47%. Every time I take a look it always says that it's in a 'regenerating' condition? Off the Wales next week but it should attempt a regen before then, not on a motorway, so that will be the test.
Anyone got any ideas on this permanent regenerating condition and is the regen figures stated above normal. I would have expected the soot level to be far lower when I arrived home after that run.
Cheers for the continued interest

[EDC5]

Ok, have we considered the possibility of the differential pressure sensor being wrong?

If it's always reading a high packpressure then potentially the ECU will always be trying to regenerate.

Would you be able to record the differential pressures when accelerating to see if they are abnormally high?

[white exec]

Wouldn't 200 miles of largely motorway run reduce (burn off/oxidize) accumulated soot?
Aren't ceramic oxidation cats intended to do just that, when they get good and hot?
Probably wrong...

[EDC5]

I would have thought so too, but since the ECU is insisting on almost constant regenerations I'm wondering if the differential pressure sensor is feeding the ECU erroneous info about it being constantly blocked triggering the regeneration.

If that's the case then an almost constant state of regeneration could lead to a lot of diesel ending up in the sump

[GiveMeABreak]

Normally we would get a diff pressure sensor fault code if it was faulty - do we have any of those?

[moizeau]

Elis, No I hadn't, I'll try and get a reading and post the results. No fault codes Marc. Chris, I agree, I would have expected it to do a passive regen, but it seems to wait until soot levels build up and then does an active one.
Fuel economy was good, 53 mpg av over 420 miles, 80 % motorway at 75 mph on CC
I shall check the oil while I'm out there.
Cheers all, I will be back!