Fo rsome reason, some 2gnt's use a different setting on the afc than others. seems kinda strange. I was at BLKOUT's house today, and we were tooling with the car, and I was wondering why the map sensor readings were so wierd. we had it set to 6 6 on pressure (the same as chris's car) and the readings were WAY off. so I tried some different settings and found that 7 7 gave the most accurate readings on his car. kinda strange. saw it with my own eyes. both chris and joe have 97's so I know it isn't a year change thing. I guess it is just best to test your car to see which setting works best for you.
#1570, "noticed the same thing" In response to Reply # 0
I found 7 in and out gave the closest reading to what you'd expect them to be, but from what others have found out as well, as long as the settings are the same in and out, then it should work fine.
#1572, "RE: noticed the same thing" In response to Reply # 2
you guys should write up a VFAQ about the AFC on the 2GNT. Even something like piling all the bits of knowledge together in one file. Send it to me and I'll post it up.
#1573, "RE: I learned something new about the afc." In response to Reply # 0
LAST EDITED ON 07-May-01 AT 08:55 PM (PST)
Hey Armond, 100% true... We noticed something like this a long time ago... and no one has any idea.. (back on 2gna@egroups.com)
Here's the idea though... Make sure that the setting you use doesn't have a MAX boost reading... i.e. one of the settings (was it 7in 7 out?) only read up to 0.7kg/cm^3... Now usually, I don't care what the SAFC reads as long as it works, but theoretically if it should read 0.7 for any boost level above say 5psi, then it won't know how to increase fuel (because all it will ever see above 5psi is 0.7...)
Do you sort of understand what I am trying to say?
Ultimately the reading on the SAFC is for fun, and as long as its spitting out some numbers, the SAFC will work fine (cos all it does is modify a signal iby increasing or decreasing it)... The reading is for fun.
Guy RS_Guy
Damn the waiting..... It Sucks! 6.5 months counting... GTuned.com is Basically Ready!!!
on teh s-afc settings, you can set it for a 1 bar, 2 bar or 3 bar map sensor (which ever yoru car comes equiped with). it gives choices of 760mm hg, 1kg/cm2, 2kg/cm2 ( I beleive it is in etc. under graph scale). that controlls how it compairs the input voltage to actual measurements on the readouts. after you get past .7kg/cm2 or so, your voltage from your map sensor should remain constant becuase of the fcd (around 4.7 I believe). you can still lean out the mixture becuase you can always subtract voltage from the input 4.7 and not confuse the ecu. and since the afc changes teh input voltage to the ecu from the map sensor in relation to rpm and throttle position, it will just reduce the injector pulse width from being so maxed out ( I hope this all makes sense). so the static number under boost is not really hurting you that much.....unless you have to richen it, of which I don't see working. the numbers under vaccuum SHOUlD be somewhat accurate 'though. they are in metric. I think the conversion is about 760 mm hg to 30 in hg or roughly about 25.4 mm hg to every 1 in hg.(basic conversion from mm to inches really). the way I found out which sensor type worked the best with the cars is find the sensor types that give the closest rading to 0 while the car is off (because there is 0 vaccuum when the car is off). there should be abotu 3 or 4 that are close (i.e. 1 bar is NOT close). then start the car up. compaire the reading from yoru boost gauge (vaccuum gauge in this case) and the reading you are getting from the s-afc. only one will still be close to accurate (you have to do the math conversion to figure it out 'though). that will be the one that works for your car (more than likely either 6 or 7). hope this helps.
Yup, that is how I determined the correct sensor, the firsdt time I hooked up the SAFC. However, the reading is completely useless as it is never 100% accurate. The closest I got it to was 50mmHg at 0 (car off).
So do you think that the reading really matters?
BTW what I think that you are talking about 1Bar 2 Bar etc.. is nothing more than the "Scale" setting for the graph or the gauges...It just extends the scale on the graph... It actually does nothing for the performance of the SAFC!
Guy RS_Guy
Damn the waiting..... It Sucks! 6.5 months counting... GTuned.com is Basically Ready!!!
>BTW what I think that you >are talking about 1Bar 2 >Bar etc.. is nothing more >than the "Scale" setting for >the graph or the gauges...It >just extends the scale on >the graph... It actually does >nothing for the performance of >the SAFC! >
that's what I was trying to say it affects the readout, but not the tuning. the adjustments are based off the input and output voltages.
I would not swear by any of the factory instrumentation (i.e. factory o2 sensor, factory map sensor, etc.) they will always be slightly off. it just gives a close figure. I rely on my aftermarket gauges to give me the most accurate figures (like vaccuum, etc...). the afc just works better when it is closer to accurate.
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it affects the readout, but not the tuning. the adjustments are based off the input and output voltages.