Where to Find Fuel Trim Data
The easiest way to perform a fuel trim inspection is to use your Diagnostic Tester. Fuel trim data is available on all OBD-II and most OBD data streams. The following chart indicates what fuel trim data is available for diagnosis:
Fuel Trim Data Interpretation
Fuel Trim Data Interpretation
|
Diagnostic System |
Long Fuel Trim Data Parameter |
Normal Operating Range* "Possible problem indicated outside of this range |
Diagnostic Interpretation |
|
OBD (w/o serial data) |
Learned Voltage Feedback (LVF)* "Accessed at VF1 terminal of check connector, TE1 off |
2.50±1.25 volts |
LVF represents command to injection system 5.0 volts = lean condition 0 volts = rich condition |
|
OBD (with serial data) |
Target A/F |
2.50 ±1.25 volts |
Target A/F represents command to injection system 5.0 volts = lean condition 0 volts = rich condition |
|
OBD-II |
Long FT |
0%±10% |
Long FT represents command to injection system > 10% = lean condition < -10% = rich condition |
Do It Yourself Car Diagnosis
Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.
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