Originally Posted by mad_sb

No Worries Man,

Short term trims, so long as they are less than 10% most of the time and you see them swing from + to - and vice versa should be ok. It's when you start to see big numbers like high 20's that stick around around that you need to be concerned. SHort term trims go to zero as soon as the ecu transitions into open loop (no longer targeting 14.7:1).

Long term trims, work in conjunction with the short term trims. Your total trim at any time is the combination of the long and short term. Unlike the short term trims, long term trims stay active when you go into open loop. As a result, they directly affect your AFR at WOT. In general, you want the long term trims as near zero as possible. + or - 5% is ok so long as the tuner accounted for that when they dialed in your afr.

There are three knock related values. Knock Correction (CA) is the course correction, if you see an occasional -1 here you are ok. If you see a lot of -1 or any number more negative (like -2) then the tune probably needs work. Knock Correction Learn Value is the long term correction and it works with IAM (Ignition Advance Multiplier). Timing is added to the base timing map by multiplying IAM * Advance map. IAM starts at 0.7 stock. A happy tune will slowly work it's way up from .7 unhappy will work it's way down from .7. Some tuners turn off the system by setting the advance map to zero (in this case you would always see zero for the knock correction learn value). By default, no timing is added till after .6 g/rev load is reached so light throttle cruise and such knock correction learn value will be zero most of the time. You really want to pay attention to the IAM during wot or open loop, if you see it going down timing is being pulled.

AFR will depend on NA or FI and E85 vs pump. Stock sensor only reads down to 12.1:1. NA, anything richer than 12.5 is costing you power anything leaner than 13.2 (WOT) is going to be knock prone. FI, you really want to be in the 12's as soon as you go into boost and ideally drop down into the mid to high 11's (stock sensor can be adjusted to read into the 11's).

Thats should get you started :)

Originally Posted by Calum (Post 1183708)

mad_sb sent me this when asking about the same stuff.