A/F ratio with F.I.
Originally Posted by slow
you want to be richer when at wot, but part throttle, the pcm will command stoich, which is around 14.7
Ryan
Ryan
then it will command exactly what you tune it to
I liek to tell the pcm 13:1 for Part throttle and then 11.5:1 or 11:1 for WOT......
sometimes richer depending on Boost the car will try to maintain 14.7 during regular driving...........you want no higher than 11.8 ...........11.5 on a dynojet 11.8 on a mustang.
Originally Posted by shawn_c992001
I'm running ~5psi with a ratio of 14.7 is this good or bad? Would around 12 be better?
Originally Posted by slow
There is no benefit to being richer at part throttle that I have ever seen on a newer vehicle I'll do that on a fox body, to make then run smoother.
Ryan
Ryan
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What I like to do is tune for 14.7 under part throttle while in vacuum to maybe -5 inches of water. Once @ -4 in. through 0 psi & up to 4,000 RPM maybe 13.5 & from above 0 psi through 5 psi no more than 13:1 as long as there's no ping (knock) & the car is making power. Somewhere between 12.5 & 13:1 should be OK as long as timing is not advanced enough too cause knock @ WOT. It's a balance between timing & pre-detonation under boost. For sure 14.7 @ WOT under boost is way too lean. Good-luck.
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Right I tune afr to cylinder pressure. At around 0 boost I like to see 12.8-13.0:1 at wot. Then as boost comes in I will go down to about 11.8:1, for a lot of boost on pump fuel I will go even richer.
I would sy thats a bit much for even 5psi. Now lets say your iat was like 60deg with race fuel then it may be fine. How much kr are you seeing. 28 is good in vacume or up to 0psi but coming into boost you should be seeing a little less then that.
