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Discussion Starter · #1 ·
Does anyone have an Apexi S-AFC installed on a nissan altima. I bought one and am having it put on monday. I saw it on that car on the front page of altimas.net (Walton Hong) i believe his name is. Our car is not listed in the install book but the bluebuird is, the only proublem is that it is a SR and not a KA. We have the same wires they call for for connection though. The shops gonna try it and see what happins. What do you guys think?

Thanks

Josh "Swathcat" Swathwood
 

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You really don't need it unless you have a highly tuned, supercharged or turbocharged car, like Welton. The SAFC is just a fuel computer that modify's the air flow of the Intake Manifold Vacuum/Boost Pressure, Air Flow Capacity, Karmann Frequency, Engine RPM, Throttle Position, and Air Flow Correction persentage. It also has a deceleration airflow meter that helps correct blow off valve problems.

Also, what gen Altima do you have? Because I think Mike was saying something about it not even working because the fuel system in a second gen is computer operated and it will automatically correct the levels back to stock which just eliminates the SAFC all together.
 

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Discussion Starter · #3 ·
Its a first gen altima. And the reason i bought is because of Zex nitrous system i have automatical controls the amount of fuel and air it needs. But it is based off the stock ECU figures. So my guy at the shop said if i have this i can feed a more accurate amount, and a better base for the nitrous brain to read off of? I guess thats my reason for buying it. Does it shed anylight?

Thanks for the help though. Thats what i wanted was some other peeps thoughts
 

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I've got one, but my engine is the SR20DET. It should work on the KA as long as you can find the MAF and TPS signals to the ECU.

The whole point of it is to raise or lower the injector cycles by adjusting the ECU's air intake measurement. You should make sure to get an Air/Fuel Ratio gauge as well, or get it tuned with a dyno, otherwise you wasted $350.

-rw
 

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JSWATHCAT said:
i have automatical controls
hehe automatical...

yea it should do you good since ur squeezing.....

good luck with the install!

-shek
 

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Why would you get it for your nitrous system? Unless you car is running lean or rich or something? Do you know what the SAFC really does? It is a "piggy back" system that "tricks" the ecu to think that there is more air going through the MAF so it adds more fuel or vice versa. At most you MIGHT gain 8 hp, but in all honesty you probably won't notice much of a difference. But, since you already bought it, I guess try it out and see what you think. (BTW, I don't mean to come off all negative and shit, I am just trying to help you out ;) )
 

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that system is pretty much useless without dyno tuning
 

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Discussion Starter · #8 ·
i bought it brand new for 150 dollars from a kid with a GTP it wont work on domestic so he sold it. originaly i bought it to resell to someone else because of the price. but then i thought i would install on my car.
 

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Dude..about a month ago i was thinking the EXACT same thing you are right now. i had a sweet deal on the S-afc and really wanted to get it since i'm spraying nitrous too. well i called JWT and asked them if it would help and basically they told me what melanie is telling you. the 2nd gen ecu will reset the s-afc settings, defeating its purpose. if you were to install it anyway, make sure you get it dyno tuned. in my opinion, i'd say wait till around January because the rep from JWT told me they were working on an ecu (nitrous?) upgrade for 2nd gens. i'm keeping my fingers crossed
 

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melanie, how would the computer recorrect it in a second gen. All the s-afc does is change what signal the MAF sends the stock ECU, The ECU basically reads the signal from the MAF and tells how much fuel is needed to maintain or increase/decrease "X" rpm's (this is where the ECU is factory programed with a map). By changing the MAF signal it should trick the ECU because the ECU is now reading a higher or lower MAF signal because of the S-AFC and just puts whatever fuel the ECU says the engine is supposed to have for engine speed etc. You do need a air/fuel ratio gauge so that you can have a baseline/form a baseline curve for the engine before you use the S-afc to alter the air/fuel ratio. This is only needed for major mods like forced induction or nitrous......with nos how are you going to trigger the s-afc at the same time as the bottle so you dont constantly run rich?, but for forced induction I say this is better than a new ecu........you know we could figure out the JWT ecu easily if someone who has one with the turbo (at X boost) would instal a fuel/air gauge and record the ratios at diff rpms. All you would have to do then is do a mathmatical conversion between the S-afc, stock engine, and turbo JWT engine. email me

Theory sorta goes like this.....there will be an mathmatical relationship between how the S-afc changes the MAF signal to the increase/decrease in fuel/air ratio. If you can measure what the stock fuel/air ratio is across diff points along the rpms you can form a basline engine graph. If someone then measures the fuel/air ratio in a turbo'd alty (JWT ECU) across its rpms, you can see how much more fuel is needed at any RPM and using the beforehand calculation (for the relationship between the s-afc control and the change in fuel air ratio) and adjust the s-afc accordingly to deliver the correct amount of fuel.......................


you know what that means dont you.........for the price of an S-afc you get by without a 700$ JWT ecu, all it takes is someone to do the math on a turbo with JWT and a stock.......ain't reverse engineering great?
 

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alchemist said:
Theory sorta goes like this.....there will be an mathmatical relationship between how the S-afc changes the MAF signal to the increase/decrease in fuel/air ratio. If you can measure what the stock fuel/air ratio is across diff points along the rpms you can form a basline engine graph. If someone then measures the fuel/air ratio in a turbo'd alty (JWT ECU) across its rpms, you can see how much more fuel is needed at any RPM and using the beforehand calculation (for the relationship between the s-afc control and the change in fuel air ratio) and adjust the s-afc accordingly to deliver the correct amount of fuel.......................
The S-AFC uses the MAF signal to calculate the volume of air coming in, does it's correction, then sends back the approriate signal to the ECU.

The A/F ratio in ANY EFI engine should always ideally be near stoich (14.7:1) - that's what most ECUs strive to do. There's no way to measure fuel delivery of the JWT ECU unless you measure the injector cycles and fuel pressure, so using an AFC on a JWT ECU won't give you any measurements.


you know what that means dont you.........for the price of an S-afc you get by without a 700$ JWT ecu, all it takes is someone to do the math on a turbo with JWT and a stock.......ain't reverse engineering great?
The turbo ECU has a different timing map as well as the fuel maps.

-rw
 

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i never said use and afc on a turbo motor...i said to first use a fuel air meter on the turbo'd motor to map it, and then use the apexi device on a turbo'd motor to increase the fuel ratio to match that of the jwt ecu
 

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IgNiTe said:
the 2nd gen ecu will reset the s-afc settings, defeating its purpose. if you were to install it anyway, make sure you get it dyno tuned. in my opinion, i'd say wait till around January because the rep from JWT told me they were working on an ecu (nitrous?) upgrade for 2nd gens. i'm keeping my fingers crossed
he has a first gen

i was thinkin' about gettin one after i do my engine work....
it'll prob add only about 8hp to a stock KA....
but wit all mods...
the more u modify and add on...
the better each modification works...
:)
 

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alchemist said:
i never said use and afc on a turbo motor...i said to first use a fuel air meter on the turbo'd motor to map it, and then use the apexi device on a turbo'd motor to increase the fuel ratio to match that of the jwt ecu
You're confusing: "never said use afc on a turbo motor.".... "then use the apexi device on a turbo'd motor to increase ..." ???

Well, either way, point is you can't do any mapping with an AFC and/or A/F meter. The A/F would always be at or near 14.7:1 on any turbo/nos/na car. All you gotta do is keep your A/F near 14.7:1 with whatever ECU/engine you have.
 

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alchemist said:
melanie, how would the computer recorrect it in a second gen
Because, the second gen's fuel system is computer operated. Don't believe me? Ask JMT yourself, or do a search on i-club.com, the 2000-2001 Impreza's have the same problem.
 

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Discussion Starter · #17 ·
So whats the verdict, if i have them dyno it will it work? Even if its 8 or ten horsepower for 150 dollars that aint bad? I can always resell it later for that kind of money. Besides it looks good. Bad idea or what?
 

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IgNiTe said:
Dude..about a month ago i was thinking the EXACT same thing you are right now. i had a sweet deal on the S-afc and really wanted to get it since i'm spraying nitrous too. well i called JWT and asked them if it would help and basically they told me what melanie is telling you. the 2nd gen ecu will reset the s-afc settings, defeating its purpose. if you were to install it anyway, make sure you get it dyno tuned. in my opinion, i'd say wait till around January because the rep from JWT told me they were working on an ecu (nitrous?) upgrade for 2nd gens. i'm keeping my fingers crossed
I also spoke with a rep from JWT. He mentioned that they are in the process of developing the computer for 2gen altimas.
 
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