RI_RS4 wrote:
Arthur, no need to resort to colloquial slurs. It weakens your argument.
As for properly operating vehicle, that's a sufficiently vague statement. I've never argued 20% loss. Do not put words into my mouth. My statement is quite simple:
IVD causes a loss in intake flow due to increased and unwanted turbulence, and increased timing pull. This reduces top end power and removes the "torque hump" at 5500 rpm. Net impact is 5 to 10% reduction in top end power. I've never said anything other than this. The performance difference can be felt and is measurable.
This is a "known issue" impacting the entire Audi/VW FSI line, but is normally not noticed in lower performance engine families. Due to it's unique high performance nature, the RS4 engine - and it's driver - is sensitive to these 5 to 10% changes in engine performance, especially in the high rpm performance.
I agree with you that for there to be larger power losses, approaching 20%, that there have to be additional cascade failures. In some cases, I suspect that mechanisms behind IVD are the root cause, and that the cascade failures - ram change over flap sticking, coil failures - are secondary results of the initial problem. (i.e- misfires caused by carbon deposits can cause excessive discharge voltages in the coil pack, causing accelerated insulation breakdown and increased incidents of misfiring.)
We can agree that codes will be set if the intake ram changeover flap sticks. We can also agree that misfire events will be logged. But to my knowledge, only catastrophic knock events are logged. Normal timing pull due to fuel quality, CC deposits ... etc are not.
I suspect that Audi (and other GDI engine manufacturers) see IVD as an acceptable risk that can be managed at the service level, since most owners of the majority of Audi vehicles will not notice a 5-to-10% reduction in performance at the top end. RS4 and R8 owners are unique in that regard. They live for that last 5%.
firstly, it's not a 'slur'
my 'arguement'?
actually it's a rebuttal to your 'theory' and misleading information that you (and others) propogate
as I previously pointed out, there is no way deposits cause a 10% loss in volumetric efficiency, and that is the only way a 10% loss torque can be realized since displacement and compression remain the same (as does the number '4' and Pi~3.141596....)
IVD is not a 'risk', it is a natural consequence of the design
if the dew point is 50, and the temp drops to 45, you get fog...
if you have a DI engine you get deposits
neither is a 'problem'
but at least VW/Audi have instituted measures/methods/procedures to mitigate those and eliminate any impact on performance
all the while gaining all the benefits of DI, higher Cr, better specific output, efficiency gains, etc.
you never get something for nothing...but in this case the downside is negligable (if even quantifiable) and the benefits tangible...
if timing is pulled to it's limit (and it is a small fixed range so that the engine meets enviornmental regs) and remains there, as it would with impact from deposits, low grade fuel, etc., it sets a code, it's the law...
they want to make sure engines operate in the region they were EPA typed and approved...otherwise they will pollute at a higher rate than authorized
