brettsb16a2

Thanks Alot, i am working on vacuum side right now, got the boosted side still real rich. I don't hit much boost and if i do, it kills the bugs.

Toysrme

Set it to the low 16's. Say around 16.2 or 16.3. Beware of misfiring when you get into actual lean burns around 19-22:1 under light engine loads.
Keep in mind that you're not going to gain much, if at all on these small over-worked engines by going leaner than the low 16s. At that point, the leaner you go the less the power output. Eventually you run out of power output needed to maintain speed.
I've shown this before to JD's chargin. But I've seen this Toyota chart in several non toyota and general refferance automotive txt books. (aside from being in all the T-Ten literature)


See if that helps you any.

dcg9381

I've found that different vehicles tolerate a wider range of mixtures than others.
I tune to 14.9 AFR for cruise. If you can tune leaner than that without power loss or EGT impact, go for it.

The issue that i've seen is that somewhere leaner than 14.9:1 you start to feel the power drop off. The ECU will dither - cross back and forth over your desired AFR and you'll feel the power come on and taper off.. It's annoying - so either go richer than that point or adjust your 02 correction so that it does slow more slowly.

cloud

or disable the o2.

power doesnt really drop off until like 17.5 18 if that... it just idles rough.

kablammyman

i've noticed this too since my car's vac afr is between 16s and mid 14s. Crusing afrs arfe pretty easy to deal with since the car isnt working too hard and theres little consequence for not having it perfect. Its the high load, low rpm portions of the map that needs to be perfect, and it can be easily overlooked.

marcj

I get about 14.4:1 but i'm on a stock P30 basemap with low compression pistons, so it's just a tad bit rich.. not going to bother tuning now it since i'll be boosting in a few weeks.

Chris Harris

on who's dyno...

miss-piggy

On gasoline, best power is made between approximately 12 and 13:1 AFR. Any richer or leaner kills power. Pick up Jeff Hartman's EFI tuning book. Read it. Then post.

cloud

^ I meant that's the way if it feels on my car. I thought someone said something about drivabilty with leaner a/f ratios.
my cars tune is messed up right now and I'm running lean when its cold and it runs maybe a little rough where it hits certain rpms. then gets past it. which is probably my tune and no cold start enrichment. but when its warm, leaner mixtures, I dont feel a power loss driving normally.