Originally Posted by cryo
The 05/06 models have it as well although not a cruise/non cruise style. It also maxes as 2000rpms stock. I Was in the middle of building a map so I figured I would check and confirm. Looks like it may be an option as well for those who suffer from it. I've never spent too much time trying to tune around it because no one had found the mechanical issue causing it, I hope this turns out to fix it once and for all.
After doing some checking myself, I note that Cobb's latest STi tune has both tables retuned from OEM... shifting compensations to apply at different RPMs. Other tunes for other cars seem to vary similarly, all trying to account for an itch no one seemed able to locate to scratch. Until now.
Considering how high the compensations are, how focused they are cell-to-cell, one would think that zeroing these tables would create chaos in an otherwise stock fuel system... never mind a stutter or two. But in fact the opposite is true when the extra fuel line is installed AND the tables zeroed... the engine becomes incredibly smooth.
One of the things I always check are Cyl 3&4 Knock Sum totals. I don't record them but they tell me things after enough time. Oddly, while these totals include actual accountable knock events, they're most often elusive to pinpoint. What stands out in the little driving I've done since installing the fuel line is how LOW the Knock Sums have become. No other tuning I've done has impacted this parameter as significantly as this mod.
I haven't mentioned how different the idle has become, but it has... and there was nothing wrong with it before.
It makes sense to me... considering what was going on "backstage" as the Load Compensations played a virtual song with the injectors, modifying fuel independently from all other tuning inputs... instead of being the regulated standard most think our fueling depends on. Wrong. Wrong that causes unexplained low level knock... when the Load Comps are not in sync with engine reality. Wrong even in the best of circumstances, like when there is no egregious Studder to complain about... because behind the seemingly smooth engine is in reality a granularity, or continuous background of fueling errors. The difference between unfinished wood and a polished handrail.
In short, it is simply not possible for any car with these tables active to operate smoothly... in the manner of a polished handrail.