Supracentral
03-14-2007, 03:19 PM
http://www.well.com/user/mosk/Vfsignal.htm
The Vf1 output has three different types of Vf output.
o2 Sensor Feedback Mode
Diagnostic Mode
Learned Value Mode (<-- this is the one we are talking about for tuning)
1. Oxygen Sensor Feedback Mode.
* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm
Result of Ox sensor signal processing:
5v=Rich
or
0v=Lean or Open loop condition
_______________
2. Diagnostic Mode
*T and E1 connected
*Engine off
Results of Diagnosis:
5v=Normal, No trouble codes stored.
or
0v=TCCS Trouble code stored. View the 'Check Engine' Light, It will blink codes.
________________
3. Learned Value Mode
*T and E1 not connected
*Any operating conditions, RPM's, or speed.
The Vf line feeds five stepped voltage values of 0,1.25, 2.5, 3.75, 5.0 volts
Meaning: Result of Air-Fuel ratio voltage feedback
Learned Value: It is a fuel injection correction coefficient which tailors the standard fuel injection duration to minor differences between engines due to manufacturing tolerances, wear, and minor mixtures disturbances like small vacuum leaks.
This coefficient is capable of altering the calculated injection {before Ox correction} by as much as 20% to prevent Ox sensor correction from being excessive.
If you encounter a driveability problem that sets number codes, this Vf voltage feedback can be of some help, especially code 25/26. (engine condition rich or lean)
_______________
Note:
Discard Vf reading when engine is cold- It will be fixed on 'Rich'.
The Vf learned value tells you how hard the ECU is working to keep the engine running properly.
After loss of power to ECU, it will take a certain amount of time to relearn, depending on the engine model and vehicle driving conditions.
The ECU will learn faster if the input signals are stable- Water Temp, Air Temp, Throttle position sensor, Air, O2, etc..
At high altitude operation, Vf can be 0v 'Lean' but it is considered to be normal. {lack of oxygen}
Vf voltage can be "border line" also, flipping back and forth between 2 ranges.
The Vf1 output has three different types of Vf output.
o2 Sensor Feedback Mode
Diagnostic Mode
Learned Value Mode (<-- this is the one we are talking about for tuning)
1. Oxygen Sensor Feedback Mode.
* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm
Result of Ox sensor signal processing:
5v=Rich
or
0v=Lean or Open loop condition
_______________
2. Diagnostic Mode
*T and E1 connected
*Engine off
Results of Diagnosis:
5v=Normal, No trouble codes stored.
or
0v=TCCS Trouble code stored. View the 'Check Engine' Light, It will blink codes.
________________
3. Learned Value Mode
*T and E1 not connected
*Any operating conditions, RPM's, or speed.
The Vf line feeds five stepped voltage values of 0,1.25, 2.5, 3.75, 5.0 volts
Meaning: Result of Air-Fuel ratio voltage feedback
Learned Value: It is a fuel injection correction coefficient which tailors the standard fuel injection duration to minor differences between engines due to manufacturing tolerances, wear, and minor mixtures disturbances like small vacuum leaks.
This coefficient is capable of altering the calculated injection {before Ox correction} by as much as 20% to prevent Ox sensor correction from being excessive.
If you encounter a driveability problem that sets number codes, this Vf voltage feedback can be of some help, especially code 25/26. (engine condition rich or lean)
_______________
Note:
Discard Vf reading when engine is cold- It will be fixed on 'Rich'.
The Vf learned value tells you how hard the ECU is working to keep the engine running properly.
After loss of power to ECU, it will take a certain amount of time to relearn, depending on the engine model and vehicle driving conditions.
The ECU will learn faster if the input signals are stable- Water Temp, Air Temp, Throttle position sensor, Air, O2, etc..
At high altitude operation, Vf can be 0v 'Lean' but it is considered to be normal. {lack of oxygen}
Vf voltage can be "border line" also, flipping back and forth between 2 ranges.