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Discussion Starter #1
I have a MAFT setup and am using the zeitronix wb. the maft instructions say to get the vf reading to 2.5 but I cant seem to get to stay above 1. From what I have read 0=lean and 5=rich. Does any one have any experience with tuning using the vf? My a/f's are between 14 and 15 at cruise and when I boost to about 2 o3 psi it starts to drop around 11. So according to the vf I am still running lean I dont understand what is going on.
 

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What are you using to tune with?

From everything I have read on the Maft, it should be used primarily as a device to replace the AFM and you should still have something else for tuning purposes.

The VF voltage in only relevant on closed loop, the problem as I understand it is that the ECU builds your open loop maps based on closed loop corrections so you want the Vf in closed loop as close to 2.5 as possible.

Dan
 

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Discussion Starter #3
I have a MAFT setup and am using the zeitronix wb.
I stated what I am using. I need to get a good base setting before I try using my safc-2 to fine tune.
 

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Discussion Starter #5
I am not using it to tune my car, I am trying to tune it to get as close to stock as I can and then I will use my safc to do the tuning. Basically I need to know if I need to get the vf reading to 2.5 or if I can just use the a/f reading on my wideband.
 

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2 things here.

first, just use the a/f on your wideband. dont worry so much about the vf. thats is mostly for people that dont have a wideband.
second, you are kinda confusing what the actual voltage means.

0v means the ecu is leaning the fuel calculation, not that you are running lean. it means you are richer than you should be.
5v means the ecu is richening the fuel calculation, meaning you are leaner than you should be.

2.5v of course means it is right where it thinks you should be. so long as it is any where from 0v-2.5v you are fine. remember vf is only useful in closed loop (less than 75% throttle) and not wot.

either way, just refer to the wideband and keep the vf under closed loop in the 0v to 2.5v range.

hope this helps clear things up

dave
 

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Discussion Starter #7
Thank you for setting me straight because you are correct about me being confused. I knew I was running rich on the wb with an a/f reading of 12-13 at idle and cruise and I know it should be around 14-15 but the damn vf reading was sitting at zero which is what I was so confused about. Thanks for the HELP!!
 

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Discussion Starter #9
Now you've got me confused, which one is it?
It was both because I have been turning the knobs on the maft to try and get the vf to read 2.5 but I was adding fuel because I thought my car was running lean. I have a about an hour worth of data logging with different settings. So as to which one is it? It is both and I even have more results than just those 2. Thanks for trying to help though but dbsupra cleared things up for me.
 

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Just remember the VF is telling you what the ecu is doing to get the wideband reading you are seeing. (it's not saying you're rich or lean, it's saying it's using a richer or leaner mix to give the normal a/f) Your a/f could seem perfect but you are pegged at 1 or 5 because the ecu has compensated to give that a/r, and the VF is telling you roughly how much. Start by resetting the ecu, then tune the closed loop (cruising, light throttle) so it floats around 2.5. That may take a good deal of correction. Also if you do not reset the ecu, the ecu will compensate from your change and you may end up with a vf that has flipped from 1 to 5. For open loop (WOT) just tune a/f - the VF isn't telling you anything.
 

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It can also go to 0 volts if the ECU finds the mixture quite rich and is adjusting the fuel more than 11% to lean it out according to Reg Reimer.
 

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Discussion Starter #15
I get mine off my zt2 wideband
 

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malloynx said:
where is everyone pulling vf readings from. i don't get them with my LM-1 wideband.

does the s-afc display them?
yes the afc will display in sensor check if you hook up the blue wire to the vf signal at the ecu.

i found the detailed vf info i was looking for earlier if anyone wants more details. very well written.

http://www.supras.com/04/resources/index.php?id=80&q=vf

cnewingham- glad i could help :)

dave
 
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