Can anyone help with mystery intermittent fault

bigjl

BeenThroughItAll wrote: »

If it's producing that much smoke, it suggests the DPF may be fairly clogged when regeneration is taking place. That being true, when it happens do not turn the engine off, or stop driving, until the regeneration is complete - if you do, you'll end up with badly diesel-contaminated engine oil which will not be positive.


The Z19DTH and Z19DT equipped vehicles don't actively regenerate unless DPF saturation is quite high; under normal circumstances they will passively regenerate during long drives, when constant higher engine speed will allow the exhaust system to get hot enough to regenerate the DPF.

If the car's doing active regenerations, that indicates either you're not doing long enough trips often enough, or there is a fault with the DPF or associated differential pressure sensors.


To put this into context, in 18 months and around 30K miles, my wife's 9-3's DPF saturation maintained a level of ~40-50% and never once did an active regeneration; instead passively regenerating once a week during her normal travel pattern.

When I drove Zafiras with that engine regularly, 3 years roughly at least 48 hours a week, they would Regen every couple of days or so, I would never turn off when it was doing one unless I had to and I found it was less troublesome if you kept it running even when parked up.
But it would regularly do an Active Regen, several times a week and often when getting back to station after a shift, meaning Inwould have to take it for a quick spin.
It once started to Regen and stunk out the Garage when it was sitting ticking over at start of shift, one of cycle boys once burnt his leg on it when squeezing past the back of it to get to some shelving.
I drove a few over the years and they were all rubbish on diesel even when you tried to be economical, little to no standby with engine running etc, could never get them to crack 20mpg (they were Autos though)
The same car always had less problems when I was running it on the expensive BP diesel than it did when other people filled it with normal BP Diesel.
And I know what I make of that but I am not going to derail the thread.

Paperbird

We had exactly the same with our 2007 93 last year (owned from 2008). For about 8 months while doing a regen it would throw out smoke when accelerating away from roundabouts and junctions even though it was getting regular motorway runs that should have kept the DPF clear.
It went into limp mode with a DPF fault, my local specialist (SAABtec) did a manual regen and sold me a tin of Saab branded fluid to add to the fuel. According to the blurb it would lower the temperature the soot burned off at during a regen. It did say to use it every 3 months but I only added it once and 10,000 miles later it is still smoke free.

henrik1971

Thanks all for your responses, very reassuring, and better / more informative than certain mechanics at certain garages!
Perhaps I went a bit over the top about the mortifying amounts of smoke, but it does shoot out the odd cloud or two here and there. In commuting traffic, I can see the car behind me backing away, as they probably don't enjoy it coming through their cabin vents!

I do just need to do a few good runs in it. 90% of my driving is 5 mile commutes to and from work.

Paperbird - if you know the name of that magic fluid, I would be glad to hear what it is - I'd certainly buy some. I already add Redex diesel from time to time and that seems to give the car a bit more zip between 1700 and 2500 revs when the turbo kicks in.

To be fair the car has now done 163k miles, I bought it at 4 years old at 90k miles for peanuts, albeit within two years I had to do timing belt and water pump, then heater matrix, then air con resistor, then an injector, EGR valve, two cabin fans, wiper motor, alternator, injector wiring harness, and of course the lovely clutch and DMF for £850 at 125k miles! Other than that, and going through roadsprings like there's no tomorrow, its been a nice car to own and drive. Never break down in France though. I had European cover, but trying to find a dealer back in 2010 was like looking for a needle in a haystack!

Iceweasel

henrik1971 wrote: »

90% of my driving is 5 mile commutes to and from work.

That's your problem.

No need for any further investigation or suggestions.

Diesels with DPFs shouldn't do short journeys.

Paperbird

I can't remember the name of it but you could try phoning Saabtec. I paid £10 for it but there are others on the market that claim to do the same thing.

bigjl

The DPF Regen additives are all similar to Eloys Fluid in that they reduce the temperature required for a Regen.

The first in the market was JLM and I have used it a couple of times.

It is best to view using something like that as preventative maintenance to be honest if you do mainly short trips.

The reason I have avoided buying another diesel is that most of my miles are short local trips and the wife is the same.

Tha was why we kept the Clio DCi for so long as it was a late 56 plate and towards the end of the period when they had no DPF.

After six years it was going to need money spent and I didn't want to spend it.

I would buy another Clio though, at the moment I am looking into small engines petrol cars for the daily duties.

There are reasons why vehicles fitted with the 1.9cdti lump were so often treated to a DPF removal and they aren't because it was the best system on the market.

Though 55 and 56 plate Zafiras still fitted with DPFs are still running round London everyday, I doubt many have done less than 200k. I also doubt many are in their original engine.

BeenThroughItAll

Paperbird wrote: »

I can't remember the name of it but you could try phoning Saabtec. I paid £10 for it but there are others on the market that claim to do the same thing.

Any of the off-the-shelf DPF cleaner additives will be the same. They contain additives including Cerium compounds which lower the temperature at which the soot in the DPF can be burned to ash.


You can buy them from ECP, Halfords, etc, or online. Be aware though, when I've tried them before when I've bought cars with DPFs they've had no measurable impact upon saturation levels as measured by the emissions control system.