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View Full Version : AFC Adjustment


tmiller24
10-18-2002, 08:56 PM
What will the adjustment screw on the end of the AFC do? Three years ago I bought a big Fiver and wasn't happy with 160 horses anymore. The trailer salesman send me to a shop that disconnect the wastegate and adjust the torque plate,after they removed the cover on the end of the AFC and made a change there also. Sure did pull good afterward, but I just recently bought new exhaust and a set of guages only to find temps out of control. Blind BOMB'n ain't good.

Superduty12v
10-19-2002, 01:12 AM
The screw sets the spring strength. What it does is this: You pump has a pre-boost max fuel setting, when you go your pump goes to this limit and by this time boost builds which pushes on the spring, which allows the governer to let the fuel rack move even further. It takes a certin amount of boost to condense the spring for more fueling. Loosening the screw weakens the spring, in turn making the little boost you have at low RPMs push the spring in a lot further than before which adds more fuel before and after boost because the same amount of boost is pressing against a lower tension spring. IE: 10psi is giving you more fuel rack movement after the adjustment than 10psi was allowing the fuel rack to move before. Hope this answers your question some what.

tmiller24
10-19-2002, 08:05 PM
Yea, that helps a bunch. I expected to hear something similar to that, but was hoping it would have a little more to do with fuel timing fine tuning. My next experience, with this truck, is to buy the tools and learn to do timing adjustments!Without a doubt, you guys, on this site, are the best!<br>THANKS Superduty. 8)