Does anyone know what the recommended a/f ratio is on a 03 TL-S. Mine is at 12.5-12.6 WOT...just seeing if i need a tune..i am NA

 

Gasoline motors all make peak power at 12.9 to 13.1 air/fuel ratios - so you are a bit rich. However, most factory computers run it a bit rich so they won't have to deal with detonation and possible engine damage under warranty.

 

How does a person know what their A/F ratio is ?

 

most find out while on a dyno, or with a wide band o2 and software

 

I ran my evo WOT @11.4-11.6. Most important is that you have no knock.
AEM wideband is what I used. Of course I had AEM ems.
Most dyno's use the tail pipe which tends to read a bit leaner than in the DP.

 

A car with forced induction requires totally different A/F ratios than a naturally aspirated car. N/A at WOT should be about 13:1. F/I at WOT should at peak boost be about 12:1 and then at peak power dip down to 11.5:1