Audi VAG Carbon Build up - Direct Injection - inevitable?
Discussion
Noticing at 100mph (track) my B9 S4 was only doing 2k rpm in 8th gear, even manual upshifts couldn't get it near 3k rpm when cruising speeds. Accelerative redlines don't count as they have to be consistently above 3k to burn off carbon build up.
This is simply not possible these days with emission regs meaning low rpm, lower 95 RON specified (S4), less detergent, lower motorway speed limits, congestion etc, with direct fuel injection how do you ever have the chance to clean your engine properly to remove carbon deposits from the engine, or is it a head off clean every 50k as part of the maintenance schedule?
This is simply not possible these days with emission regs meaning low rpm, lower 95 RON specified (S4), less detergent, lower motorway speed limits, congestion etc, with direct fuel injection how do you ever have the chance to clean your engine properly to remove carbon deposits from the engine, or is it a head off clean every 50k as part of the maintenance schedule?
How does the 'Italian tune up' remove carbon from intake valves on a direct injection engine if the only thing passing through the valves is air (with some oil vapour)?
I have a B8 S4 and my understanding is that it will eventually get some level of carbon build up on the intake valves as they are not being 'washed' by fuel as would a conventional port-injection engine.
Am I missing something here? like does the B9 have secondary injectors through the intake port?
I have a B8 S4 and my understanding is that it will eventually get some level of carbon build up on the intake valves as they are not being 'washed' by fuel as would a conventional port-injection engine.
Am I missing something here? like does the B9 have secondary injectors through the intake port?
catso said:
How does the 'Italian tune up' remove carbon from intake valves on a direct injection engine if the only thing passing through the valves is air (with some oil vapour)?
Similar in principal to an electric oven's 'self clean' function. With no fuel cooling the intake valves, it's possible to raise combustion temperatures enough to bake the intake valves to 500 deg C, at which point carbon burns off. The sustained 3K thing comes from VAG themselves, it's not an internet myth.
Whether or not it actually works in the real world is unknown as no one periodically removes their intake manifold to check, and even fewer people know about it, or even care because the bulk of VAGs are leased, so carbon build up is the private buyers problem 3 years down the line.
It might work if practiced from new, but attempting it with 150K's worth of carbon isn't going to do s
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