Boost Lee

iTrader: (3)

I recently blew the engine in my TII. Since then I've replaced it but i want to ensure that it doesn't happen again. So i've decided to put in 680cc injectors as secondaries and a bigger fuel pump. As we all know, this will result in a richer mixture which will also cause performance problems.

I keep hearing about the S-AFC, but i don't understand what it does. Does it control fuel amounts? or does it tell the ECU different things about incoming air flow so that the ecu can decrease the amount of fuel? If that is the case, will decreasing the amount of fuel cause a lean condition (which would again pop my engine)?

Please clarify the purpose and the method that the S-AFC uses to fix the fuel richness problem encountered by an upgraded fuel system.

Also, are there any other methods available to alleviate the rich mixture problem besides the S-AFC that won't cause my ********* to fall off in fright?

-Anochie

Boost Lee

iTrader: (3)

so nobody knows?

image4you2see

i would like 2 know if the s-afc is worth it. im going to a single turbo on my 93. i have a s-afc i havnt used yet i want to know if this is enough or should i go with somthing different.

Barwick

I think it just alters the fuel opening durations somehow. I don't know if you can lower the duration though. I've never used one, only heard of lengthening the duration. If you're using larger injectors, then you're probably running more boost with an intake/full exhaust, and might need the larger inejctors.

Merovign

The AFC intercepts signals from your Air Flow Meter to your ECU and lies to your ECU about the air flow so it will alter the Fuel Flow into the engine.

Basically, in theory it does exactly what you want for about $300.

You'll have to ask someone else if it actually will work for your application, I don't have one yet, but I've heard good things about them.

jspecracer7

It always seems as if these questions about the S-AFC pop up on a weekly basis. I have answered this same question about a dozen times already.

Here we go again:

The S-AFC stands for Super Air Flow Converter. It interrups the air flow signal coming from the MAF meter and adds or subtracts a % of the total air going into the engine by + or - 1% increments up to + or - 50%.

It controls fuel amounts by telling the ECU that more/less air flow is coming in. This applies for the FC, not for the FD since the FD uses a MAP sensor vs. MAF meter.

It does NOT control individual injectors. It control the injectors overall. It adds/subtracts from the primary injectors until they reach 40% duty cycle(Unsure of the percentage when the secondaries come on line) and then it add/subtracts from both the primary/secondary injectors at the same time.

It can NOT change your injector sizing. 5% on a 720cc injector is different than 5% on a 550cc injector.