Originally Posted by
swingtan
I can see a few big issues with not setting up B1213 in a stock tune. Basically, just driving around in summer, the IAT's will get very warm, leaning out the mixture and causing the O2's to tell the ECM to add more fuel. This of course will increase the LTFT amounts to match. But when you give it a bit of a run on the open road and hit PE, the LTFT will add that fuel to the commanded and you'll end up with a very, very rich mixture. Maybe this is one reason why the stock tune end up so rich ( in addition to the VE table and MAF settings ).
The reason for correcting the AFR drift is really more to do with consistency rather than out right performance. For example, imagine you set up the VVE on a cold day with lots of open road driving. Then after setting it all up, a few weeks later the temp rises and you get caught in traffic, heat soaking the intake and the IAT's rise. If you were to "give it a boot full", the mixtures may be significantly leaner than commanded and the timing too great for that mixture. You'll end up with KR where previously you had none.
You could probably tune the KR out with the IAT timing table, but you would then be running much less timing than you could be, if the mixtures were correct.
Simon