Whose used an AFC before??

Posted: Sat May 20, 2006 10:56 am Post subject: Whose used an AFC before??

anyone willing to give me a hand or walk me through how to tune my car useing my AFC? ive got a few sites bookmarked that give me a general idea but its all jiberish to me.

anyone willing to meet up and help me toy with my car?
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MODS: Stock

Posted: Sat May 20, 2006 11:27 am Post subject:

what version afc?
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2004 Yukon XL Trying to keep stock
2000 gtp Custom I/C, TOGs, Custom PCM, 3.25'', HAI, VS cam Retired

Posted: Sat May 20, 2006 4:04 pm Post subject:

In you scanner setup to log the following: MAFF and LTFT. Then set your AFC to 100% across the board and drive around for about 30 minutes at different speeds from idle to 55-60 mph, but do not go into PE (i.e. no more than 50% throttle).

Bring the file into excel. add a column called "decade" and the formula for the column is INT (MAFF/1000) . I.e. you are dividing the MAFF by 1000 and getting the whole number, it will be 1 through 7.

Now sort this column in ascending order.
Finally, subtotal the worksheet at each change in Decade, and you want the average of the LTFT column. This will tell you how to adjust the AFC.

Starting at 2, adjust the AFC down (less than 100%) if the LTFT average is negative and up (more than 100%) if the LTFT average is positive. For each 3%-5% change in LTFT, change the AFC 1%. I.e. if LTFT for the 2 range is -12, dial in about 98%. Do this for all the ranges on the worksheet.

Now on your log file, add B1S1, KR, and IPW. Go drive around some more, and this time do some WOT runs from a dig or slow roll.

Open the log file, and do the formula/sort/subtotal thing again. Note your new LTFT averages. You can then make adjustments again to keep these around +/- 3%. Check to see where teh LTFT is locking in at WOT. Note your O2s where you have KR. Typically in the 8, 9, and 10 ranges you will start bumping fuel (102% - 104%) to steady out the B1S1 and quench the KR. ALso check the IPWs, they should be in the 18-19 ms range.
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1998 Silvermist GTP Coupe
Bone stock unicorn
1998 True Green Metallic GTP Coupe
Pullied, cammed, intercooled. With a kiddie seat. It once ran a 13 flat.
1998 True Green Metallic GTP Sedan (retired)
Stock: 14.33 @ 96.5
PB: 13.89 @ 101 mph

Posted: Mon May 22, 2006 9:36 am Post subject:

its a 2.0

thanks for all the info mike, i saved it on my computer. ill have to re-read it 15 more times to makes sure i understand it all Very Happy

I think i get the jist of it, now i just gotta get my hands on the auto-tap again.

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