S-AFC vs NOS conflict
07-12-2002, 11:41 AM
#1
Senior Member
Thread Starter
Join Date: Mar 2002
Posts: 476
Likes: 0
Received 0 Likes
on
0 Posts
S-AFC vs NOS conflict
Heres the problem... Using the S-AFC on my N/A setup I lean out the top end about 14% and get good gains... However I want to get the 82011 Zex nos kit. So I have to upgrade my fuel pump to be safe correct? (Walbro 255)
Only gonna do the 50 shot but I want to be safe, and I have a tonne of N/A mods already. But heres the dilema, the new fuel pump is gonna make me run rich at WOT, good for NOS, but what about running leaner for the N/A setup? Not using the NOS I want to be in the stochiometric region, which I can do using the S-AFC, but how do I know when I fire the NOS that the zex controller will inject enough fuel espically with the S-AFC now set close to -20% (to compensate for the fuel pump)?
Red, Random, Decker?
Thanks!
-Steve
Only gonna do the 50 shot but I want to be safe, and I have a tonne of N/A mods already. But heres the dilema, the new fuel pump is gonna make me run rich at WOT, good for NOS, but what about running leaner for the N/A setup? Not using the NOS I want to be in the stochiometric region, which I can do using the S-AFC, but how do I know when I fire the NOS that the zex controller will inject enough fuel espically with the S-AFC now set close to -20% (to compensate for the fuel pump)?
Red, Random, Decker?
Thanks!
-Steve
07-12-2002, 12:03 PM
#2
Guest
Posts: n/a
The S-AFC should when on spray adjust the a/f ratio back to where it should be when before on spray. If it is not enough for the ZEX to be happy the ZEX will then up the fuel pressure to where it needs to be. I dont see a conflict here unless you already want to run too rich for some reason. The 50 shot zex should be fine with a ton of N/A mods ie I/H/E. When on NA the s-afc will not add the fuel because the N2O will not be casuing the car to go towards lean. If you have it set lean already at the top end I would fatten it up a little bit. The S-afc if a/f ratio is on the rich side will thin the mixture out, if on the thin side already the ZEX will fatten you up. Basically the S-AFC should be working more on the top end and the ZEX more on the bottom ends of the A/F mixture. I really don't think one of them should try to fight each other because they will end up coming to a happy medium. If you want good power while on spray you are going to have to most likely sacrifice some top end power. And vice versa. The zex kit though should be able to up fuel pressure enough to where it out of the reach of the S-AFC to be able to bring it back down from the fat side. I hope this makes sence. smile.gif And I hope I am right. I am sure Random or Jaws will reply at some point in time but for now, my opinion is all you got. smile.gif
07-12-2002, 03:37 PM
#3
Senior Member
Join Date: May 2001
Posts: 1,436
Likes: 0
Received 0 Likes
on
0 Posts
The S-AFC has absolutely zero bearing on nitrous tuning. It is unaware, nor can it be MADE aware, of A/F ratio or nitrous use.
You tune the S-AFC for best operation with the car normally aspirated. When you're spraying, you use the ZEX methods to make sure it's ok on spray.
You tune the S-AFC for best operation with the car normally aspirated. When you're spraying, you use the ZEX methods to make sure it's ok on spray.
07-12-2002, 05:06 PM
#4
Guest
Posts: n/a
QUOTE
Red:
The S-AFC has absolutely zero bearing on nitrous tuning. It is unaware, nor can it be MADE aware, of A/F ratio or nitrous use.
You tune the S-AFC for best operation with the car normally aspirated. When you're spraying, you use the ZEX methods to make sure it's ok on spray.
Red but doesn't the S-afc take its's readings from the O2 sensor? When he sprays its going to lean out a little right or does the zex kit just up the fuel pressure where it *thinks* it should be without reading a/f ratio first.
The S-AFC has absolutely zero bearing on nitrous tuning. It is unaware, nor can it be MADE aware, of A/F ratio or nitrous use.
You tune the S-AFC for best operation with the car normally aspirated. When you're spraying, you use the ZEX methods to make sure it's ok on spray.
07-12-2002, 11:53 PM
#6
Senior Member
Thread Starter
Join Date: Mar 2002
Posts: 476
Likes: 0
Received 0 Likes
on
0 Posts
Both the Zex kit and the S-AFC are open loop operation, meaning that they have no form of feed back to know if they are running too rich or too lean. The ultimate S-AFC would be one that hooked up to the 02 sensor and did self diagnoses to adjust the A/F ratio, but currently they don't.
Red, by the zex method, what exactly does the zex do to fuel pressure or injector pulses etc... on spray? I know that at 6k RPM the S-AFC will be trying to keep the A/F ratio stochiometric by leaning it out,(shorter pulses) but wont the zex be trying to raise fuel pressure to run it richer?
So won't the shorter pulses vs the higher pressure be cancelling each other out, to a certain extent? Or am I missing something?
Thanks,
-Steve
Red, by the zex method, what exactly does the zex do to fuel pressure or injector pulses etc... on spray? I know that at 6k RPM the S-AFC will be trying to keep the A/F ratio stochiometric by leaning it out,(shorter pulses) but wont the zex be trying to raise fuel pressure to run it richer?
So won't the shorter pulses vs the higher pressure be cancelling each other out, to a certain extent? Or am I missing something?
Thanks,
-Steve
07-13-2002, 08:04 AM
#7
Senior Member
Join Date: May 2001
Posts: 1,436
Likes: 0
Received 0 Likes
on
0 Posts
Don't try to over-think it and make it all harder than it is.
The S-AFC has no direct control over anything, it only is there to alter the MAF signal. It doesn't directly interface with the injectors, it doesn't tap in to your nitrous kit, it doesn't do anything else whatsoever. It just tweaks your MAF (or map or Karman or flapper or whatever your car has)
Thus, don't think about the S-AFC messing with your fuel at all. It's your stock computer that ultimately controls the fuel.
Therefore, it would be no different installing ZEX on a fully stock normally aspirated car as it would installing it on the same fully stock normally aspirated car with an S-AFC. The stock computer is still what ultimately decides to send the fuel.
The S-AFC is NOT an open-loop only part, it CAN be used in closed loop. The only problem is, most OBD-2 cars will still try to *over learn* what you've specified in the S-AFC during closed loop anyway. Older cars that aren't OBD controlled won't learn around it.
Tune the S-AFC to make the most power while not spraying. Then use the ZEX methods (whatever they use -- pressue is fine) to make sure it runs the best on nitrous.
DO NOT TUNE THE S-AFC WHILE SPRAYING.
The S-AFC has no direct control over anything, it only is there to alter the MAF signal. It doesn't directly interface with the injectors, it doesn't tap in to your nitrous kit, it doesn't do anything else whatsoever. It just tweaks your MAF (or map or Karman or flapper or whatever your car has)
Thus, don't think about the S-AFC messing with your fuel at all. It's your stock computer that ultimately controls the fuel.
Therefore, it would be no different installing ZEX on a fully stock normally aspirated car as it would installing it on the same fully stock normally aspirated car with an S-AFC. The stock computer is still what ultimately decides to send the fuel.
The S-AFC is NOT an open-loop only part, it CAN be used in closed loop. The only problem is, most OBD-2 cars will still try to *over learn* what you've specified in the S-AFC during closed loop anyway. Older cars that aren't OBD controlled won't learn around it.
Tune the S-AFC to make the most power while not spraying. Then use the ZEX methods (whatever they use -- pressue is fine) to make sure it runs the best on nitrous.
DO NOT TUNE THE S-AFC WHILE SPRAYING.
07-13-2002, 07:24 PM
#9
Senior Member
Join Date: Aug 2001
Posts: 5,550
Likes: 0
Received 0 Likes
on
0 Posts
heh?
viper?
i think you mean venom wink
venom works by pulsating the injectors
the zex kit does its thang by increasing pressure. As soon as you begin to spray, ZEX will suck more fuel. ZEX has NO CLUE if your running lean or rich,... all it knows
FULL THROTTLE--(then)-- SPRAY + INCREASE FUEL PRESSURE
thats it...
It will not affect your SAFC or vice versa
A while back ago, someone mentioned a new ZEX kit version that had came out. I have no idea if that one has a A/F built into it,... if so i apologize
The only kit that i know about that messes with the A/F ratio is the venom kit.
viper?
i think you mean venom wink
venom works by pulsating the injectors
the zex kit does its thang by increasing pressure. As soon as you begin to spray, ZEX will suck more fuel. ZEX has NO CLUE if your running lean or rich,... all it knows
FULL THROTTLE--(then)-- SPRAY + INCREASE FUEL PRESSURE
thats it...
It will not affect your SAFC or vice versa
A while back ago, someone mentioned a new ZEX kit version that had came out. I have no idea if that one has a A/F built into it,... if so i apologize
The only kit that i know about that messes with the A/F ratio is the venom kit.