BMW 320i M Sport Touring - Catalytic Converter - Cleaning Additives?

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Sat 11 Feb 2012 16:29
BMW 320i M Sport Touring - Catalytic Converter - Cleaning Additives? - arlowood

Just put my 08 plate 320i M Sport Touring into my local BMW specialist for a regular brake fluid service.

Only had the car 3 months and had experienced a few misfires and generally sluggish acceleration. Car had done 33000 miles when purchased and I don't do a huge mileage - about 7000/year.

Asked the garage to do a diagnostic check on the EMS and they reported that the check had shown up a blocked catalytic converter. They had put a proprietary additive (not sure which one) into the fuel and advised me to go out and "drive the car as if i had stolen it"

Went for a blast down the motorway for about 50-60 miles but not sure if that will be enough to affect a clean out.

My questions are - How efficient are these cleaners and how much high rev driving must i do to get them to work?

Also given my generally low annual mileage - how often will I need to treat the catalytic converter to prevent blockage or will driving "hard" when I do travel be enough?

Any recommendations on which additives are reputed to do a good job?

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Sat 11 Feb 2012 16:55
BMW 320i M Sport Touring - Catalytic Converter - Cleaning Additives? - piston power

Get the engine up to temp and drop to 3rd and floor it, take the revs high and hold it there for a time, you may see a cloud of black muck come out the exhaust.

More commonly known as a "Italian tune up".

7k is not much for a touring sports car it's built for speed not pooting around town, so best give it what it desires from time to time. :-)

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Sat 11 Feb 2012 16:57
BMW 320i M Sport Touring - Catalytic Converter - Cleaning Additives? - Railroad.

If the catalyst is blocked then it could be beyond repair, meaning no additive will do any good. Ignition misfires can cause catalyst damage because unburned fuel from the cylinder which isn't firing can collect inside the catalyst and ignite. This will cause the already hot catalyst to become even hotter and melt down into one solid lump. Exhaust gasses are then restricted causing a loss of power. If the catalyst is blocked then a new one may be your only answer. Be sure to cure the misfire too or your new catalyst will suffer the same fate.....

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Sat 11 Feb 2012 17:39
BMW 320i M Sport Touring - Catalytic Converter - Cleaning Additives? - unthrottled

Any recommendations on which additives are reputed to do a good job?

Yes. Bog standard 95 Octane.

Catalytic converters do not become blocked like DPFs. They are not traps. You were sold a pup.

If there is a problem with the cat, you have a problem with ignition or incorrect fuelling further upstream.

'Italian tune ups' do not fix broken cats. You need a new garage.

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