Author Topic: Rough Running a decoke?  (Read 403 times)

auntyneddy

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Rough Running a decoke?
« on: May 27, 2018, 02:57:31 PM »
I have just received my copy of  'Gems Good Motoring' magazine and read with interest about a chap with a  Mini ( BMW) that was running rough. The garage told him 'the cause of poor running is due to the top of the engine needing to be decoked'. The chap thought decokes went out with cars decades ago.
It seems the garage was correct.
I quote from the Gem magazine:  ' Modern engines tend to develop harmful deposits that can lead to them operating inefficiently'  There is research into trying to deal with this problem. Minis,various Peugeots and Citroen are prone to a rubbery-carbon deposit building in their cylinder head inlet tracts, which is caused by exhaust gases( that enter the cylinder in certain running conditions, via the EXHAUST GAS RECIRCULATING VALVE, to lower NOx emmisions) attaching them selves to viscosity modifiers in the engine oil that works it's way into the inlet tract. The build up can become severe.'
The good news is it is not 'off with it's head' but a new system of using 'a walnut shell blasting technique'. The problem is so common some main dealers are buying their own blasting kits. It is not obvious how they get into the combustion chamber no doubt with a micro surgery type camera and attachments.
I thought this was worth repeating as the good old VGR valve question raises it's ugly head frequently and we joke about how  the Italian tune up will help. However it makes no comment about Honda engines so perhaps they are superior to the PSA/BMW engines.

culzean

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Re: Rough Running a decoke?
« Reply #1 on: May 27, 2018, 03:36:47 PM »
Carboning up, particularly inlet valves seems to be a pretty big problem on direct injection petrol engines, and VAG are some of the worst.  My brother just got rid of his less than two year old  Skoda for this and other reasons to do with its reliability to date, he is getting a Suzuki Vitara as a replacement - I know Suzuki make good reliable engines but am  a bit concerned where the actual cars are made* (they have a tie up with Maruti in India that makes some models).   Modern clean refined fuels were supposed to make decoking a thing of the past, and I am convinced that a vehicle that is never revved much may still suffer from it, and I put my trust in Italian tuneup and regularly going past 3000 revs as a means to keep engine and CAT healthy.

*checked and the Vitara is made in Hungary.
« Last Edit: May 27, 2018, 03:50:04 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

MicktheMonster

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Re: Rough Running a decoke?
« Reply #2 on: May 29, 2018, 10:27:01 AM »
About 10 years ago we had a fleet of Mitsubishi Shoguns at work which all coked up due to sitting idling and slow driving without any fast blasts to clean it out. The  ECU used to make the engine surge in an attempt to overcome the problem, but like hanging onto a runaway horse, great fun!
Mitsubishi altered the design to keep our business, two more generations of Shoguns we had never suffered this issue.
We've now changed to land rover discovery sports, great road car but not as heavy duty as the trusty Shogun.

richardfrost

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Re: Rough Running a decoke?
« Reply #3 on: May 29, 2018, 12:55:59 PM »
If an 'Italian tune up' is what I think you mean - a sustained blast at higher revs - then my little Jazz gets one every time I drive it. Since I had a serviced by an actual independent mechanic, and had 8 new plugs fitted, it is enjoying a new lease of life with me and is my first choice for a Spring/Summer commute across the moors to Bradford. It's only the woolly steering that lets it down from being a 'sporty' little car. It is a different animal once the revs get above 3000.

culzean

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Re: Rough Running a decoke?
« Reply #4 on: May 29, 2018, 01:43:54 PM »
If an 'Italian tune up' is what I think you mean - a sustained blast at higher revs - then my little Jazz gets one every time I drive it. Since I had a serviced by an actual independent mechanic, and had 8 new plugs fitted, it is enjoying a new lease of life with me and is my first choice for a Spring/Summer commute across the moors to Bradford. It's only the woolly steering that lets it down from being a 'sporty' little car. It is a different animal once the revs get above 3000.

Yep.  Italian tuneup is giving the engine a good workout, the CAT a good cleanout and the oil a good warming up (to get rid of any water / condensation) .  Most local mileage cars would benefit greatly from this at least every couple of weeks.  Motorway miles are much kinder to cars than local miles,  that is why I am always wary of very low mileage cars.

For a proper Italian tune up you have to blow the horn frequently as well  :o (and get a louder one because the OEM Jazz horn is embarrassing).
« Last Edit: May 29, 2018, 02:02:03 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Jocko

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Re: Rough Running a decoke?
« Reply #5 on: May 29, 2018, 02:22:25 PM »
When I had my FIAT 126 I was ignored by everyone so I bought and fitted a set of Maserati Air Horns.
They were just a single tone, very loud and strident, and I mounted them right behind the number plate.
I wasn't ignored again!
You can see them in this image.

culzean

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Re: Rough Running a decoke?
« Reply #6 on: May 29, 2018, 03:39:05 PM »
When I had my FIAT 126 I was ignored by everyone so I bought and fitted a set of Maserati Air Horns.
They were just a single tone, very loud and strident, and I mounted them right behind the number plate.
I wasn't ignored again!

I got a Fiat horn from a local scrapyard for my first Jazz - much louder than the feeble Honda offering.  Also my mate gave me a Ford twin tone horn for my first Civic - wow it was pretty loud.  Why are Honda horns so embarrassing ?
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

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