vafc help?

[spoolinLSVTEC]

i have a 92 hatch with an h22a swap. i was wondering if anyone could help me with the settings on my vafc. i have read up on it and understand how to change settings and what they do, but i'm still very confused as to what to change. would anyone be willing to tell me what changes would be good for me to do. any help would be greatly appreciated.

[Prelude707]

You need a dyno with a wideband O2 sensor to do it correctly. Don't half-ass it and try to do it yourself. You can seriously mess up your engine. Just my .

[civickiller]

yup you need a wideband so you can find out how much fuel you need till its ok. but with a vafc you cant change timing so you arent getting max hp.

[o0Quicksilver0o]

http://www.geocities.com/thermalfid16/VAFChack1.html
basic starter settings till you get it dyno tuned/wide band tuned

[97CivicX]

note that the settings in that write up are for 440 or 450 injectors. setting stock injectors to -40 trim will kill your engine. be smart and dont change the settings unless youve got a wideband

[o0Quicksilver0o]

well the afc leans your car out so you HAVE to get bigger injectors to even it back out. DO NOT RUN THE AFC ON STOCK INJECTORS!!!!

[Prelude707]

Posted by o0Quicksilver0o - 11-03-2004 at 08:54 PMwell the afc leans your car out so you HAVE to get bigger injectors to even it back out. DO NOT RUN THE AFC ON STOCK INJECTORS!!!!


Ummm....no. Everything this guy said is incorrect. The VAFC only leans the A/F mixture as much as you want. You could even make the car run richer if you wanted to. Look at me, I'm running it on stock injectors. Please do not post information if you don't know what your talking about.

[97CivicX]

the afc isnt just made for FI cars. you can tune your car with stock everything using the hack. by only +/- a few points you could possibly get a decent amount of power out of your car.

[o0Quicksilver0o]

so your telling me that your trying to flow enough fuel to run boost with out bigger injectors...? i am just saying every one i know that has cut that corner has regreted it completly. i bet you dont have enough miles on it to beable to tell how fuck up things are. good luck with your fuel system or engine for that matter

maybe this well help clear some shit up

So, how does it work?

Well, with a forced induction setup we obviously want to supply more fuel while in boost than stock would allow us. This is where the AFC comes in. The unit allows you to richen or lean your fuel +/- 50% The unit does this by interceoting your MAP signal and modifies it to trick your ECU into thinking you are getting more or less air than you actually are. So that sounds great. I'll go pick up an AFC and use it on my stock fuel setup. Well, thiis is where the problem is and why the "hack" was thought up. If you just richen up your boosted car using the stock injectors, your MAP sesnor will read boost and throw your ECU into limp mode. Why does the ECU go into limp mode? Well, your ecu does not have fuel tables for anything above vacuum, so it shits a brick. Wow that sucks huh? This is where we buy larger injectors. Most people go for 350-550cc injectors. Of those people the most popular are the dsm 450s and the RC 440s. These are the most popular because they offer the best idle on stock fuel maps but still allow you to boost 8-12 psi before going into limp mode.

How do I set the AFC for larger injectors?

We are actually going to lean things out with the AFC. If we just stick in larger injectors the car won't even run. It would be ungodly rich running on the stock fuel map. The ECU has no idea there are 100% larger injectors sitting in the rail and is still sending the same injector pulses. So how much should you lean out? Let's say you have 240cc injectors stock (most civics) and you want to idle a set of 440cc injectors as if they were stock. With a little math we see this:

240/440 = 54%/100%

So we need to take 46% of the fuel away from 440cc injectors to run them like 240cc injectors. Now this is not a perfect conversion because there are more factors than this, but it gives you a ballpark # to start with. As for settings under boost that varies a lot, but under WOT and full boost of 8-12psi a setting of -35 to -30 on the AFC should keep things good and rich.

[97CivicX]

quicksilver were you talking to me? im not saying run a turbo car on the stock injectors, im only saying you CAN tune a stock car with the hack. i suppose you could run stock injectors with turbo though. running the same limitations as an FMU.