I'm beyond stupid when it comes to S-AFC's or any other piggy back computer. I have searched but really didn't find a post that explains them to any detail.

Can someone knowledgable about this topic please explain in detail how a piggy back computer works and what it does. What you can and can't control with one also.

Thanks in advance.

 

What you can and can't control with one varies depending on what piggyback you buy. What it does also varies depending on what Piggyback you buy.

Going with the example you gave, the S-AFC.

The S-AFC intercepts the MAF signal before going to the ECU, then alters the MAF signal up or down 50%, then sends the signal to the ECU as "modified". This "fools" the ECU into adding more or less fuel. It's limitations are based off air flow readings and fuel injectors. At idle, your MAF should read between 0.198 and 0.400, if you cut the reading 50%, it can trigger a CEL. On the other side of the scale, the MAX allowable MAF reading by the ECU is 21.9 If you hit 22, it will trigger a CEL and go into "limp" mode. If you adjust the air flow up to high at high RPM...you can trigger the "MAF out of range" error. I have YET to hear of anyone having either of these problems, but they are a theoretical concern.

 

The term ''piggy back computer'' is any electronic device that attaches TO (but does not replace) the stock computer in order to override some functionality.

The ''piggy back'' you purchase will depict what function it overrides. In the example of an S-AFC, you are overriding the MAF signal in order to fool the stock computer into sending more or less fuel.

 

can you please mention a couple of manufacturers of these piggy-backs, especially the S-AFC.
thanx

 

apex-i, field.
MSD is great for ignition

 

S-AFC Apex-i (www.apexi-usa.com) (fuel)
ITC Apex-i (www.apexi-usa.com) (ignition timing)
Rev-Speed Meter Apex-i (www.apexi-usa.com) (Speedo, tacho, and estimated HP/torque figures)