Decarbon Engine Service
- Thread starter Oxide™
- Start date
It is amazing that manufacturers haven't considered the impact of this process on their cars. I was told that different oils and more regular changes would help, if not solve. Speaking with Audi people back when I had the RS4 they suggested various oil breather solutions but none seemed confident they completely addressed the issue. Porsche are suffering this problem on the Cayenne and I believe the new 911 is prone too.
That's what I'm led to believe the problem is on the Mini at least. Glad I went for the supercharged one instead of the new turbo one.
A catch can in the crankcase breather can reduce the problem, but even modern engines that burn the crankcase fumes will have carbon build-up on the valves, combustion chamber and worse, the Cat.
Just having injectors in the inlet tract improves the situation for the valves, but you will still get deposits on the cat and inside the engine. If the cat is fouled your HC emissions will go up due to the unburnt fuel failing to catalyse fully.
Also engines are still set to run slightly on the rich side to preserve the cat, so you can still get some build up in the combustion chambers, although not to the degree of an older carbed vehicle.
Just having injectors in the inlet tract improves the situation for the valves, but you will still get deposits on the cat and inside the engine. If the cat is fouled your HC emissions will go up due to the unburnt fuel failing to catalyse fully.
Also engines are still set to run slightly on the rich side to preserve the cat, so you can still get some build up in the combustion chambers, although not to the degree of an older carbed vehicle.
This was the main reason I had maybe 6-7 emissions lights during my first year with the RS4, it was down to this coking issue and the knock on effects of it. I was one of the first cars in the UK to get the volume of lights and certainly the first in my local Audi dealer and this is when the process of testing began and I left them with the car for close to 6 weeks at one point and this is why they threw in 12 months free warranty when the inital 3 year rand out. It went through a number of software updates as they tested it and the reality is that in the end the software update they rolled out across the netowrk simply turned up the tollerance levels on the emissions light! I believe the newer RS5 version of the engine addresses many of the breathing issues, though I suspect not all and I know V8 R8's can also suffer this problem and the associated power drain. I believe cleaned cars can show over 30bhp increases on the same rolling road, so it would seem that this does cause an issue that effects the cars performance.
As with all these things actually getting to the facts and the cause/effect isnt a work of moments.
As with all these things actually getting to the facts and the cause/effect isnt a work of moments.
On another oil related point, my father reckons his newish 911 (with the new DFI engine) is using 1.5L of oil each 1000 miles, the first car he can recall using oil anywhere near this level. Porsche are working with him to monitor and do regular checks and I would not be surprised if this is a DFI thing as they seem to be desgined to actually burn oil from what I can tell. My GT3 never used a drop, not even after hard running as an example and I never put any in it in between services and it was checked weekly.
Well just a small amount of sooting inside an engine acts as a heat transfer agent, Having the inside of the cylinder head and sometimes the piston too, can reflect the heat energy back into the combustion and improve power.
On my old racing engines this was worth 1-2 BHP compared with an unclean combustion chamber. Larger deposits can glow and cause premature ignition.
Many cars nowadays have a higher resistance to fouling and improvements in fuel and oils have helped with this, but they are far from immune as some suggested on the first page.
On my old racing engines this was worth 1-2 BHP compared with an unclean combustion chamber. Larger deposits can glow and cause premature ignition.
Many cars nowadays have a higher resistance to fouling and improvements in fuel and oils have helped with this, but they are far from immune as some suggested on the first page.
Associate
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- 24 Aug 2007
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I asked a similar question on my local forum as i also saw the program and thought of my AMG C32, and this was the answer
"Carbon deposits in the combustion chamber and top of the piston act as a heat insulation layer and act to improve the thermal efficiency of an engine
thus allowing more of the heat energy from each combustion stroke to be converted into physical power.
Only when the carbon deposits become highly excessive and start restricting gas flow through the valves do they become detrimental to performance/efficiency.
though this is usually a result of oil getting into the combustion chamber through leaky valve seals or piston rings.
Many engine tuners searching for efficiency coat the piston crowns and cylinder head with an insulatiing ceramic coating to mimic the action of a carbon layer without having to wait a few thousand miles for a carbon layer to build up.
Try taking the car for a good run with the engine up to temperature (Also known as an 'Italian Tune-up')
If your engine uses a lot of oil and your exhaust is smoky this stuff won't improve it
I tend to view these products and their claims as snake oil "
"Carbon deposits in the combustion chamber and top of the piston act as a heat insulation layer and act to improve the thermal efficiency of an engine
thus allowing more of the heat energy from each combustion stroke to be converted into physical power.
Only when the carbon deposits become highly excessive and start restricting gas flow through the valves do they become detrimental to performance/efficiency.
though this is usually a result of oil getting into the combustion chamber through leaky valve seals or piston rings.
Many engine tuners searching for efficiency coat the piston crowns and cylinder head with an insulatiing ceramic coating to mimic the action of a carbon layer without having to wait a few thousand miles for a carbon layer to build up.
Try taking the car for a good run with the engine up to temperature (Also known as an 'Italian Tune-up')
If your engine uses a lot of oil and your exhaust is smoky this stuff won't improve it
I tend to view these products and their claims as snake oil "
Except they don't, they act as a heat absorber and cause more heat soak and expansion of the piston crown leading to faster wear.
If you want a combustion chamber to absorb less heat, you polish it into a reflective surface, physics 101, black radiates and absorbs heat more readily, a reflective surface resists heat absorption.
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No, because it does not have direct injection.
Soldato
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Fuel will still wash it off the intake valves of a non DI petrol though.
I'm not sure that's true; there are some quite famous engine tuners (e.g. Bill Blydenstein) that suggest their engines make better power after the pistons and combustion chambers have built up a coating of carbon.
Carbon in the form that is deposited on the piston and head doesn't have a particularly high thermal conductivity, certainly nowhere near that of aluminum or cast iron so it's much more likely that it reduces the transfer of heat compared to a bare metal surface. In fact this low thermal conductivity is the reason that excessive carbon build ups cause problems with pre-ignition.
Soldato
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My car's done 175k with the inlet manifold and head not being cleaned, with an EGR active.
Maybe cleaning it up would help my power
Maybe cleaning it up would help my power
Associate
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Soak in petrol then sling it in the dishwasher!
Just don't let the missus catch you at it.
Just don't let the missus catch you at it.
Soldato
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I rebuilt a cylinder head in her sink, I didn't think she'd mind. We broke up... wonder if that had anything to do with it.