Modern turbodiesel problems

[TW]Fox

[TW]Fox

[TW]Fox

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Hi guys,

Was reading the other day about this problem affecting Octavia TDI's, now I've found mention of it affecting Nissan Qashqai as well and was wondering how much of an issue it is with modern diesels purely out of idle curiosity.

Basically, in order to meet emissions regulations most new TD cars have a Diesel Particulate Filter. However, in order to burn off the crap the DPF filters, the car has to be driven at reasonable speed for a sustained amount of time. Fine if you drive to work up the Motorway every day but not if you drive through town lots.

If the DPF becomes blocked, the cars go into failsafe mode and need to be reset by the dealers. I've read a story of one guy moaning that he has to take his Octavia in to get it reset pretty much monthly - and is charged each time!

Any of you modern TD guys had this or know any more?
 
Not the first time I've heard this, mainly about VAG diesels for some reason. BMW's seem to regenerate the DPF in a different way so don't suffer from the same issue.
 
Might be the type of DPF? Ford have started to put them on their 2.0 TDCI 136 Diesels and you have to pay chunk more just to have the DPF! Havent heard of any problems so far from people I know with them.
 
I think there's active and passive DPF regeneration - active is where it has some way of artificially raising the temperature to burn off the soot accumulated and passive is where the exhaust gas is supposed to heat the DPF up to burn the soot off. These are the type that can cause problems if not driven 'properly'.
 
This is talked about on the Audi forums too. Short journeys, low RPMs, DPF can't get up to temperature so never gets to complete the regeneration process to burn off the soot.

The PD170 was the first modern VAG to have one fitted, afaik which I find strange as Pug were throwing them in the XUD et al from 95 onwards.
 
We had an email at work about this with regards to our combo vans a while back(1.3cdti fwiw) where we would have to drive at a reasonably high, sustained speed to clean the filter, because people with vans in London would rarely get past 20mph and unable to perform what was needed we were told we should go to one of our motor transport workshops if 'clean' ever popped up on our dash.
 
That's the only reason VAG have used a DPF?

Not heard any problems with the Audi DPF TDIs, only that they hate remaps. I'm glad mine is a PD but now Audi have made the diesel engines common rail, about time some say.
 
a hopefully quick explanation of dpfs from someone who works developing diesels.

the DPF is basically a big ceramic sponge that stores the soot leaving the engine till such time as it can be burnt cleanly. this is necessary due to emissions rules namely euro 5 which puts far stricter allowed levels of hydrocarbons leaving the exhaust.

the soot burns when it hits around 500-550oC so it doesnt happen around town unless the exhaust gas is artificially heated. higher loading diving gets the exhaust gas closer to the required temps so the ecu only has to add a little more heat to start the soot burning. around town it is quite hard to get the soot to burn as the way the car does this is to post inject fuel (ie inject after the the piston has gone down the bore) this burns in the oxidation catalyst just before the dpf and rapidly raises the temperature till the soot burns
if the car is at low revs low load then isnt enough exhaust gas flow to be able to heat the dpf up to get it to burn so it just fills up.

the only way to fix this is to go an get the car upto to proper temps for 30mins or so and it will sort it out itself no need to take it to the dealer.

if you live in a city and only drive round the city DONT BUY A DIESEL!!!
 
cossey3 said:
the only way to fix this is to go an get the car upto to proper temps for 30mins or so and it will sort it out itself no need to take it to the dealer.
Click to expand...

If you dont do this many cars will go into limp home mode which DOES require the intervention of the dealers.
 
dpf.png


From VW :)
 
I've also heard about this from a chap who I talk to on msn about diesels in general....

He told me what you've said Fox, pootling around town = Problems.

Surely the owners of cars with this filter should just give them one hell of a thrashing each week ?
 
[TW]Fox;11909457 said:
Hi guys,

Was reading the other day about this problem affecting Octavia TDI's, now I've found mention of it affecting Nissan Qashqai as well and was wondering how much of an issue it is with modern diesels purely out of idle curiosity.

Basically, in order to meet emissions regulations most new TD cars have a Diesel Particulate Filter. However, in order to burn off the crap the DPF filters, the car has to be driven at reasonable speed for a sustained amount of time. Fine if you drive to work up the Motorway every day but not if you drive through town lots.

If the DPF becomes blocked, the cars go into failsafe mode and need to be reset by the dealers. I've read a story of one guy moaning that he has to take his Octavia in to get it reset pretty much monthly - and is charged each time!

Any of you modern TD guys had this or know any more?
Click to expand...

This is why it is crucial to use the correct oil in DPF equipped vehicles. Burnt oil forms ash and will block the DPFs. You need Low SAPS products (Sulphated Ash, Phosphur and Sulphur) These are denoted by being ACEA CX products
 
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