Car says catalyser is blocked

As cold weather approaches my Passat starts to tell me that the Particle catalyser is blocked.

reading the manual it says to drive for 20 miles at 40 mph to burn it off.So thats down the M2 to the first turn off and back.

I seem to remember that in the cold season the oil/fuel suppliers add up to 15% Kerosene to the Diesel to stop it waxing. As it is advised as Bio Deisel I wondered if waxing was still a problem

Not waxing; your dpf is blocked because the exhaust stream is not getting hot enough to burn off the deposits. Italian tune-up will do the job

Edited By john halfpenny on 20/10/2020 22:24:23

Clive,

If that is all it takes to clean yours your lucky, 2018 my Subaru said the Particulate filter was blocked so took it along our local dual carriageway at 70 in third, no joy so paid a visit to nearest dealership and they removed the filter and cleaned it for £500. It ran for a year and up popped the alarm again so took it to village garage and he plugged in his box of tricks and it wouldnt let him force a regen so took it to another Subaru dealership as the other garage had lost theirs, they checked it over and said it was chocker and they wouldnt clean it so £2000 later it was fitted with a new filter, pipework and pressure sensors. Its now a year on and the alarm hasnt shown but I do give the car a low gear high rev run once a month to clear its throat, which I might add I was doing before the first time it happened. My wife said sell the car but she wouldnt understand that I would have to give it away as nobody would buy it with such an expensive fault.

Martin P

I have had a few customers with this fault. Friends actually. The usual fix is a real & i mean a real thrashing down an old airstrip Or motorway if you feel lucky, will clear the fault. Failing that , there are a few companies that will do a full regen with a chemical clean. Not sure if this works but google it & see the results. You need to get the cat red hot to clear the carbon deposits from the cells before it will show clear. Petrol engines are not as bad as diesels.

SOD will be along shortly to give you a full rundown from his google searches.

Steve.

Running diesel engines at light load is never good for them. They sometimes need running hard to clear out the engine - let alone the DPF. Another problem is that, if allowed to get to the stage where they need the soot blowing out, the run to try to clear the already blocked PDF is not at ‘full’ power and even more soot would be cleared from the engine.

Many engines inject fuel twice, at regeneration times, to increase the exhaust gas temperature - once at normal timing and later for the excess exhaust gas heat. If that heat is dissipated in a cool-running turbo, the benefit is lost. I suspect that the turbo ideally needs to be running at full pressure for good PDF regeneration - ie running with a considerable percentage of exhaust gas bypassing via the wastegate.

Those that do only short journeys (school run?) will likely develop problems even earlier.

Of course, the salesmen rarely tell the potential customer of these things - all they want is a sale.

Not surprisingly, I’ve never had PDF problems, even though three Peugeot 607 cars have been automatics.🙂 But I do know some that have... Not many have seen an old Caterpillar tractor ‘wet stacking’ due to being left ticking over (because the donkey engine would need to be started to restart the main engine, if stopped).

Let’s face it not many, these days, even know how to ‘oil the dipstick’ - that is if the engine is actually fitted with one!

Looks like a run down the M2 then.

Not today though as it is pouring down here in Kent.

Clive

Unlikely - I use DuckDuckGo!

Dave

I had this problem with a Toyota Rav 4. I seem to remember the garage saying drive at 2000 revs for 20 minutes to keep it clean. Only kept the car 4 months it was the worst car I have ever had and I bought it after 40 years of running series Land Rovers !

I had this problem with our Suzuki Vitara 1.9 turbo diesel and the word that comes to mind is EXPENSIVE. I use our local garage who are very good but despite their best efforts they couldn't clear it so they fitted a new particle filter it was a pattern part as the Suzuki one was an eye watering price. The new part didnt work too well though so my garage rejected it and the supplier replaced it with a more expensive one at no extra cost. The car was in and out of the garage for about 6 weeks with a final bill of £1400

This was 18 months ago and the car is now fine but I'm still nervous that it will eventually happen again.

Interesting comments, thank you. My Ford Ranger has an indicator to suggest changing up a gear, presumably for better fuel economy with reduced engine rpm. Clearly this won't do the cat much good from what I'm reading above.

As a slight aside. I get regular reports from the Essex Police "Neighbourhood Watch" scheme, and I'm alarmed at the number of catylitic converters being stolen. Presumably because of this, and associated problems. I've fitted a "Cat Loc", as the height of the Ranger makes it easier to steal the cat. I know it's probably not very neighbourly, but hopefully the Cat Loc will make the scum bags look elsewhere for their booty.

Concerning the Italian Tune Up I was told that this was actually official poilicy withe the Tilling Stevens / Roots TS3 opposed piston diesels.

A late acquaintance used to service these engines and once complained to a factory rep about the need for regular decarbonising. Which was a fair bit of work on those. He was told to take it the vehicle out for half an hour and "thrash the living daylights out of it". Smokescreen time but the engines ran very well afterwards.

Being a two stroke the TS3 needed to be revved to keep it throat clear but most lorry and bus drivers were reluctant to do this and tended to drive it short shifting, Gardener style, and ride the torque curve. Which worked fine as the TS3 was very powerful for its size and era but clogged things up. That said with lorry / bus chassis design and brakes state of the art in those days an Italian Tune Up or revving it out every time on ordinary roads might have been a touch exciting.

From an engineering standpoint I always think it a pity that the work of Professors Timoney and Wallace on improving the efficiency of these engines was never followed up. Timoney put the shaft carrying the bell cranks connecting the pistons to the underslung crankshaft on eccentric bearings. By turning the eccentrics with a lever the effective stroke of the pistons could be varied. A spring and hydraulic damper connected the two levers dynamically self adjusted so the engine to run at near constant peak combustion pressure. At full throttle the stroke would shorten so mean BMEP would rise giving more power at the cost of efficiency. At part throttle it would lengthen improving efficiency. Given that most of the time a vehicle engine runs of part throttle fuel consumption overall fuel burn would be somewhat reduced. Allegedly 20%+ savings. Probably more as a smaller engine could be used to get the same peak power.

Wallace took a leaf out of the Napier book using the engine as a partial gas generator with a turbine driven by the exhaust connected to the drive shaft via differential gearing. Differential so that the engine didn't try to back drive the turbine. Cycle efficiency improvements of 50% or more are possible with this sort of thing. Obviously best suited to constant loads like generators.

Mid 1960's control systems weren't really up for handing such complexity but the possibilities with modern controls are tempting. The Timoney constant peak pressure system is very good for pollution control.

Clive

Taxi test clean up run required

1 go on dual carriageway

2 do 60 in 2nd or 3rd gear for 10 miles

....WAAAAAAAAAAAAAAAAAAAAAAA....

Link to Prof Timoney Timoney seems to suggest that moving the pivot changes the compression ratio. He also had a hydraulically driven booster to the turbocharger. Unfortunately I can't work out how to view the actual article rather than the transcript, if anyone can shed any light I'd be grateful.

In the 10 years of running multiple diesel cars with DPFs (all Vauxhall), I have not had any issues with the filters blocking or warning of impending blockage despite only making short journeys most of the time by following these rules:

* Identify when an active regeneration is taking place, and ensuring engine revs are kept above 2000rpm until it completes. Many problems are caused by owners inadvertently switching off the engine mid-regen and the cleaning cycle never fully completes. This can also cause issues with the excess diesel injected finding its way into the sump and diluting the oil therein

On my vehicles, it is determined that a regen is active by a change in drivability/throttle response, increased fuel consumption determined by trip computer (goes from the usual 0.3gal/h at idle to 1.0+), increased idle speed, stop/start system inhibited, heated window switched on by control system, change in exhaust note and 'hot' smell from exhaust.

* Ensure engine ancillaries are all in good working order, especially EGR valve and intake system downstream of the turbo. Slight leaks in these areas, which may not bring on the engine management light, can result in increased soot production which is not accounted for by the engine control system. This results in the filter filling up sooner than expected and can lead to a 'filter blocked' warning before an active regen is triggered.

New petrol vehicles that meet Euro6.2 emissions regultaions now come with a GPF fitted, so changing to petrol is no longer a guarantee of avoidance of problems in the exhaust filter area. These do have slightly different method of regenerating, usually this is done passively during the driving cycle when the vehicle coasts down hill off the throttle. Excess air passing through the engine reacts catalytically in the GPF and burns off any accumulated soot. Still reports of problems on the forums though, due to some drivers not following typical driving patterns, or vehicle software going awry!

Ladmachining,

In my working life I drove many diesel vehicles mostly Vauxhall cars and vans and none of them gave any activity that you describe, my current vehicle is a 2009 Subaru Forrester 2.0 litre turbo diesel and that needs a fault analiser plugged into it to see the regen history, I get no performance change or increase in fuel consumption, she is regularly garaged serviced and spends her working life towing a trailer with my hobby in going to rallies all over the country so life isnt easy for her, except the last six months but its still happened twice.

Martin P

Back in the day my old man used to add a gallon of petrol to a tank of diesel in winter to stop waxing. These days we all get winter diesel so it no longer happens. Only use the 5% biodeisel if it stays in the tank a long time.

I had the same fault coming up on one of my cars, Dealer wanted over £2k to fix, I did the run at high revs, put additives in, no help.

Got an independent person to come out to the car and plug up the computer to see what the faults was

Turned out a temp sensor, £75 later fixed, he did say he was always hearing of people getting ripped off from dealers with this type of fault.

So get a independent auto electrician to have a look and see what the real fault is

.

I've still got an exhaust extractor for one of those, Wade RO54 makes a nice Rootes supercharger.

Technically its the expansion ration not the compression ratio that is varied as its an externally blown engine operating at near constant peak pressure. But trying to think about whats actually going on in pressure terms on the inlet and compression side makes my head hurt! In some ways the set up is effectively very steam enginey notch up et al wise.

Thats a very interesting link Duncan. I'd not realised how closely related the work of Timoney and Wallace was.

I cant figure out how to read it either.

I do have photocopies of 3 papers presented to the Institute of Mechanical Engineers on Professors Timoney and Wallaces work which I could scan and E-Mail if you want to see them. PM me your E-Mail if you want them.

Its disappointing how much valuable work foundered on re-tooling costs.

Clive

My sister had a diesel Vauxhall Astra that went back twice at 6 month intervals to have the DPF cleaned out @ around £250 a time. When the fault light came on a third time, having had little in the way of response from the dealer she complained to the finance company. Two days later the dealer were on the phone asking when it would be convenient to view alternative cars - she ended up with a newer, higher spec. petrol Astra at no cost to herself due having been mis-sold a car that was unsuitable for her predominantly local, short journey usage.

The first motorhome I had with a DPF (2013 Ducato 130) came up with the DPF fault light after 5-6000 miles. This turned out to be a blocked DPF & the failure to regenerate was down to the pipework to the pressure switch that measures the pressure across the filter had blocked with soot so the switch didn't operate. A modified switch & pipework was fitted under warranty & the DPF regenerated by running the engine hard at standstill with the van under the control of the plug-in diagnostic unit. That cost me around 1/4 tank of diesel (90 litre tank) - I guess that the diagnositic unit was injecting extra fuel during the regen cycle to burn out the soot accumulation. I had no further DPF problems with that van, or it's subsequent replacements.

I still run a diesel car as I cover around 20,000 mainly motorway miles a year. Of my 98 miles a day to and from work, around 80 are on the M62 / M1 / A1M & DPF clogging has not been an issue on the last 2 cars over the 80,000 I put on each. Mrs B. does mainly shorter journeys & runs a petrol car - fuel usage is a bit higher than a diesel, but petrols are far more tolerant of such usage than a modern diesel.

Nigel B.

Spelling edit

Edited By mgnbuk on 21/10/2020 13:38:22