Where to Find Fuel Trim Data
Total OBD & ECU Auto Diagnostics
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 |
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