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Discussion Starter #1
can you get an accurate idea of how rich/lean your running from the Vf signals? im wondering if they are just inaccurate, or maybe i need to change my afm or oxy sensor again.
 

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It will tell you above/below stoch thats it. If you are wondering if it is time to replace your sensor, there are tests in the tsrm where you count the fluctuations over a certain time.
 

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Discussion Starter #5
no, but im running super rich but my vf's still say add fuel, usually its at 5. i'm installing an afc right now, cuase i recently did the lex/550's thats why its so rich, so that should take care of it.
 

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Are you getting thick, black smoke out the back? I think you have the readings backwards:

"Remember that {0 volts Maximum Lean} does not say that the car is running lean! It is saying is that the TCCS is leaning the BASIC FUEL CALCULATION to make the mixture perfect for the current conditions. There was too much fuel calculated for the BASIC FUEL CALCULATION causing the engine to run RICH for a short time so the TCCS is reducing the fuel amount from BASIC FUEL CALCULATION. The 0 voltage LEAN is a very safe or normal reading, it is telling you that there is plenty of room to add fuel, lots of correction reserve left. Many stock cars running at high altitude will show a 0 volt condition, high altitude is less air for the engine, so the TCCS cuts back some of the fuel to compensate for the to rich mixture"

My take on the whole thing is that 0v doesnt indicate that the fuel mixture is lean, it indicates that the computer is leaning the mixture to compensate for a rich condition. Whereas 5v would not indicate that the mixture is rich, it indicates that the computer is increasing the amount of fuel to correct a LEAN condition.
 

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You should adjust the AFM (screw) so you get 2.5 typical at idle. This centers the trim so you have space to "move on each side", letting you keep the cruising fuel delivery in tune.

Running super rich is not healthy for the motor. It'll mess up your EGTs and in an extreme case, you can get fuel-wash in the cylinders and it can also build up too much deposits leading to hot spots or valve sealing issues, ect.

As others have noted, you don't use the Vf as a monitor for combustion conditions. It's an OUTPUT from the ECU that tells you how the TCCS is asjusting your injectors. The fuel trim is based on many factors

Read the full tech tip at SONIC to get the full story.
 

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Discussion Starter #8 (Edited)
i know what they are. its at 5, that means the computer is telling it to add fuel cause its lean, even though im getting black smoke and stalling and boosting egt's are 1050! i haven't been driving the car becasue i dont want to mess it up, im installing an afc, gonna get a new oxy sensor and a new water temp sensor. i also got another afm but it didn't change anything. i have the lex screw backed all the way out.
 

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hrmm

I have a lex/440 and my setup right now is tuned for ALL cruising conditions to read 2.25 volts....dont get me wrong it will swing when letting off or goosing the gas up or down hills but under the rpm range of consistant driving (idle to 4k) my vf sits right at 2.5 volts... VF is THE way to tune for cruising conditions so that the ecu has its full range of control for changing conditions... and is useless for WOT running :) thats what A/F AND EGT is for... Gotta remember when tuning you should use ALL the data available to tune to car correctly and not one or the other... Thats why the properly tuned cars put down the big HP everyday and the others blow up.........

(dont even think of starting a flame over the lex/440 setup read the sig and note the AIC 3... )
 

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Discussion Starter #10
i just installed my afc, damn that thing is nice, i cant wait to go to the dyno and have that thing tuned.

im still getting the 5 volt signal but i know im running pig rich, super low egts, i was able to get them up to 1200 cruising on the highway for awhile, but other than that they stay around 900-1050, and thats boosting at 11.

im gonna change the egt probe and check and recheck the wiring to the gauge, but i doubt its that because when i took out my o2 sensor it was covered in black stuff.

im also going to change the water temp sensor, oxy sensor, grab a couple afms from junkyards (does anyone know a way to test them, i did a test measuring the resistance but i dont think it works because both the afms i have where off but they were both reading the exact same things?) im also gonna check the tps and idle speed control.

can anyone think of any other things to do, its really bothering me knowing that my car is an idiot, "i'm running pig rich, why dont i add some more fuel". stupid supra.
 
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Chances are it's your oxygen sensor, or the wiring from it.

What happens when you create an intake vacuum leak? Does the Vf signal indicate it is trying to lean it out?

Do the TSRM tests for the oxygen sensor, and examine the wires carefully. Mine were frayed right by the power steering reservoir, where it goes into the cover running behind the timing belt.

It ran stinking rich that way.
 
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