RENR

OK heres the scenario..

your a/f 's are in teh 10's... and you want to get to 11.5...

do you

1. take fuel out??
2. add timing
or both or what the hell??

which would be better?? im thinking in theory doing one or the other can have the same effect of reaching the 11.5 mark but which is safer?? sorry im just learning this stuff

FooK

i wouldnt start adding timing, how much timing are you pulling as is?

start by pulling 10-12% fuel in your boost tables, you're definitely very rich and any way you approach the tune, its too much fuel. The general rule most people say is that 1% fuel with 450's is usually = about .1:1 AFR change.

For mine I find that about 8% = 1:1 AFR change.

scttydb411

i always get the afr good first so i know what power i'm making before messing w/ timing and add .5 or 1 degree at a time and then work the afr while adjusting the timing.

TurboEF9

AFR tuning is cake kids...

Crunch on this...

If your target is 11.5, and at whatever section you're trying to tune hits say a 10.5... how much percent do you take out to hit your target?

Trial and error is lame ----... use math.

(10/11.5) - 1 = 8.6%.. remove 8.6% from that area. Do this ALL OVER THE the map. Yes, it works even at idle. Now the $1,000,000 question, "why" does it work? ..because we already know the fuel pulse durations that are causing the actual amount, we just need to know what causes our target. So we take get the percent of different from the target from what we're actualyl making (with the already supplied pulse durations) and add that percent to it. Wa-La, air fuel ratios .1% - .3% to your target. ---- guessing.

...you're just about right.

Rory

(10/11.5) - 1 = -0.130

Did you mean to say:

%diff = [(known / calculated) / known] * 100

This yields 8.6% difference.

95RedEX

AWESOME TIP.

93turbo16

It is just basic percetage difference.. stupid math classes.. stats and BS.

But definitley hit the AFR first and have a conservative timing to start out. Your A/f can be perfect and you can still blow up a motor.

RENR

or blow head gaskets

RENR

thats a good point. the thing im trying to figure out is should i really only adjust the fuel to acheive the a/f i want?
and how do you determine if the fuel needs the adjustment or the timing?

TurboEF9

You won't know if the timing needs adjustment until you are on the dyno and see the curve.