Where to Find Fuel Trim Data

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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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