importkiller_SS

iTrader: (35)

i was just wondering if someone would be kind enough to help me on the procedures on how to directly adjust Air fuel ratio. and i need a lot of help on how to tune for spark.
i just installed arp rod bolts to my stock bottom end and i did a scan last night up to about 7k rpms and the timming seemed a bit high, more toward 27!!
shouldnt i target about 22 at WOT toward that high rpm? and my AFR was about 12.7-12.8

importkiller_SS

iTrader: (35)

o yeah i forgot to mention also i was scanning about 2.5* of KR from 6800-7000 RPMs

thanks

foff667

iTrader: (2)

Most would likely tell you to dial in fuel/spark to a value you know is close for a specific combo ie 12.7:1 and 24* of timing on a dyno until you hit the best numbers you can and then add a bit of fuel & take out a bit of timing ie if you make the best timing at 28* but 24* gives you within 1hp then just go with 24* for safety sake.

Some tune a flat pe table & alter maf to dial in afr, others will just use pe to dial in wot fueling, I won't take sides in that argument so don't put me in the middle

There are no set fast ways to dial these in so have fun trying to find 10 straight people that will agree on the best way to do it lol.

dan@masportspeedshop

iTrader: (6)

Use the PE table to set your target AFR (the AFR you want the ECM to achieve at WOT) and then correct the MAF curve if necessary to be sure that the AFR at WOT is as the PE table specifies. If it's not, and the MAF curve is off, you can't tune the ignition timing accurately as the ECM relies on the MAF curve to determine engine load (cylinder air intake) and thus set the correct ignition timing. The PE table affects strictly AFR, while the MAF curve affects both fueling and spark timing. Check out the following site...

www.thetuningbook.com

This book may be of use to you if you need in-depth information on tuning EFI. Case studies are included that show you how to tune, step-by-step.
As mentioned above, not many people will agree on the process for each individual tuning case, but everyone will agree that an improperly calibrated MAF curve will cause nothing but headaches and guess-work when tuning.

importkiller_SS

iTrader: (35)

thanks you guys for the info, that gives me a much better understanding.

that book would looks very interesting i would really like to purchase that and learn some of the techniques.

since i had about 2.5* of KR in a certain area would i round up to 3 and subtract that from that trim cell it occured in?

dan@masportspeedshop

iTrader: (6)

That's exactly what you would do. Again, as foff667 mentioned, you may produce as much torque as you currently do with even less timing, but you'd need a dyno to test and measure that. Considering you have 2.5* of KR, you should remove at least 2-3* of timing advance.
Cheers!