Smelly DPF regen

[camembert]

I've had lots of diesels in the past but my 08 2.2 Tdci S-max is the first with a Diesel Particulate Filter.

I understand that from time to time the DPF regenerates by burning off deposits. If this happens when I'm stationary, clouds of smoke billow out from under the bonnet, filling the cabin with acrid fumes. If I'm quick enough to switch the ventilation to recirc, it's not too bad, but I'm usually too slow and it's embarrassingly unpleasant for anyone in or near the car.

How this is supposed to help save the planet, I don't know. Is it normal?

John

[insanitybeard]

I don't know that much about how the engine management decides when to carry out a regeneration process and I may be completely wrong when I say this but I thought there was possibly a way in which the driver could delay a regeneration from being carried out. Does your vehicle do most of it's miles in town? Usually problems with regeneration stem from the vehicle doing lots of town miles and never getting hot enough in normal usage to burn off the deposits meaning that when it does regenerate it can be quite a smoky and unpleasant affair.

[camembert]

My driving is a pretty typical mixture of local and medium distance. eg today 6 miles then 6 miles then 40 then 40 - then a bit of back and fill in the driveway. But occasionally just 1 mile to the shops and back. In June I did 670 miles in one day! and 3 days later it still did a smelly regen.

My point is - should it billow out from under the bonnet? Why doesn't it come out of the exhaust? What is it supposed to do?

John

[insanitybeard]

Sorry, I'd not registered the smoke from under the bonnet part......... No, that certainly doesn't sound right to me. Might be worth checking with a Ford dealer for peace of mind, really you need to see where the source of the smoke is when it happens, are there any oil leaks in the engine area to your knowledge, or maybe even an exhaust with a hole or a gasket that isn't airtight?

To my knowledge regeneration involves the engine management dumping a load of extra fuel in to raise the temperature of the particulate filter/exhaust much higher than it's normal operating temperature so that the soot and other exhaust deposits are burned off, therefore I'd expect some extra smoke but not loads- unless e.g you had oil leakage into the exhaust via the turbo or something like that.

Like you say, any extra smoke you would expect to see coming from the exhaust, if you've got a load coming up from the bonnet then I would consider that a problem and certainly not normal!