Fuel Injection, Fuel Trim, and Driveability Diagnostics

01 FI01 - Fuel Injection Diagnostic Mindset and Driveability Overview

• FI01-L01 – What Fuel Injection and Driveability Diagnostics Actually Cover
• FI01-L02 – Complaint, Context, Baseline, and Verification Before Parts
• FI01-L03 – Reading Symptoms Without Jumping to Sensor Replacement

02 FI02 - Safety, Fuel Handling, Fire Risk, and Service Information

• FI02-L01 – Fuel Pressure, Fire Risk, PPE, Ventilation, and Depressurization
• FI02-L02 – OEM Service Information, Fuel Specs, TSBs, and Test Conditions
• FI02-L03 – Restricted Procedures, High Pressure Direct Injection, and Escalation Boundaries

03 FI03 - Air, Fuel, Spark, Compression, and Exhaust Diagnostic Framework

• FI03-L02 – Open Loop, Closed Loop, Feedback, and Enrichment Strategy
• FI03-L03 – Load, RPM, Temperature, and Operating Mode as Diagnostic Context
• FI03-L01 – The Five-System Model: Air, Fuel, Spark, Compression, Exhaust

04 FI04 - Fuel Trim Fundamentals and Scan Data Foundations

• FI04-L01 – STFT, LTFT, Total Trim, and What Positive/Negative Trim Means
• FI04-L02 – Fuel Trim at Idle, Cruise, Load, and Decel: Pattern Thinking
• FI04-L03 – Bank-to-Bank Fuel Trim Comparison and V-Engine Logic

05 FI05 - Oxygen Sensors, Air-Fuel Sensors, and Feedback Control

• FI05-L01 – Narrowband O2 Sensor Switching and Closed-Loop Feedback
• FI05-L02 – Wideband Air-Fuel Ratio Sensors, Lambda, and Current-Based Logic
• FI05-L03 – Sensor Bias, Exhaust Leaks, Heater Faults, and False Lean/Rich Codes

06 FI06 - MAF, MAP, Speed Density, and Air Measurement Faults

• FI06-L01 – MAF Sensor Logic, Grams per Second, Calculated Load, and Contamination
• FI06-L02 – MAP Sensor, Speed Density, Barometric Pressure, and Vacuum Logic
• FI06-L03 – Vacuum Leaks, Unmetered Air, Smoke Testing, and Trim Patterns

07 FI07 - Fuel Pressure, Volume, Pump Control, and Delivery Diagnosis

• FI07-L01 – Low-Side Fuel Pressure, Volume, Restrictions, and Return/Returnless Systems
• FI07-L02 – Fuel Pump Control Modules, Duty Cycle, Current Ramp, and Voltage Drop
• FI07-L03 – GDI High-Pressure Pump, Rail Pressure Command, Actual Pressure, and Safety

08 FI08 - Injectors, Pulse Width, Balance Testing, and Spray Problems

• FI08-L01 – Injector Pulse Width, Duty Cycle, Resistance, and Current Ramp
• FI08-L02 – Injector Balance Testing, Flow Differences, Leakage, and Dribble
• FI08-L03 – GDI Injector Issues: Spray Pattern, Carbon, Noise, and Misfire Links

09 FI09 - Misfire, Rough Idle, Hesitation, and Combustion Quality

• FI09-L01 – Misfire Counters, Mode $06, Pending Codes, and Freeze Frame
• FI09-L02 – Rough Idle: Air Leak, Injector, Ignition, Compression, or Mount?
• FI09-L03 – Hesitation, Tip-In, Bog, Surge, and Load-Based Fueling Faults

10 FI10 - Rich, Lean, P0171/P0172, and System Too Lean/Rich Strategy

• FI10-L01 – P0171/P0174 Lean Codes: Vacuum, MAF, Fuel, Exhaust, or Sensor?
• FI10-L02 – P0172/P0175 Rich Codes: Fuel Pressure, Injector Leak, MAF Bias, Purge Fault
• FI10-L03 – When Fuel Trim Looks Normal but the Complaint Is Real

11 FI11 - EVAP Purge, PCV, EGR, and Air/Fuel Disturbance Sources

• FI11-L01 – EVAP Purge Stuck Open, Fuel Vapors, Idle Quality, and Trim Effects
• FI11-L02 – PCV Systems, Crankcase Leaks, Oil Vapor, and Idle Fuel Trim
• FI11-L03 – EGR Flow, Stuck Open Faults, Combustion Dilution, and Misfire Links

12 FI12 - Throttle Body, Idle Control, Pedal, and Airflow Adaptation

• FI12-L01 – Electronic Throttle Control, APP/TPS Plausibility, and Limp Strategy
• FI12-L02 – Idle Airflow, Throttle Cleaning, Idle Relearn, and Adaptation Strategy
• FI12-L03 – Stalling at Idle, Decel Stall, and Airflow Control Decision Logic

13 FI13 - Cold Start, Warm-Up, Enrichment, and Temperature Inputs

• FI13-L01 – ECT, IAT, Ambient, and Temperature Plausibility Checks
• FI13-L02 – Cold Start Enrichment, Long Crank, Flooding, and Start-Stall
• FI13-L03 – Warm Restart, Heat Soak, Vapor, Pressure Bleed-Down, and Injector Leak

14 FI14 - Catalyst, Exhaust Restriction, Backpressure, and Fueling Consequences

• FI14-L01 – Catalyst Efficiency, Downstream O2, and Fuel Control Misreads
• FI14-L02 – Exhaust Restriction, Backpressure Testing, Low Power, and Load Data
• FI14-L03 – Exhaust Leaks Before Sensors and False Lean Strategy

15 FI15 - Mode $06, Graphing, Data Logging, and Advanced Scan Strategy

• FI15-L01 – Graphing Fuel Trim, O2/AFR, MAF, MAP, Load, and RPM Together
• FI15-L02 – Mode $06 Misfire, Catalyst, O2 Monitor, and Test Result Interpretation
• FI15-L03 – Data Logging Intermittent Hesitation and Driveability Events

16 FI16 - Direct Injection, Carbon, Turbo Fueling, and Modern Engine Strategy

• FI16-L01 – GDI Carbon, Intake Valve Deposits, Misfire, and Airflow Distortion
• FI16-L02 – Turbocharged Fueling, Boost Leaks, Load, Lambda, and Knock Protection
• FI16-L03 – High-Pressure Fuel Limits, Rail Drops, Limp Mode, and Stop-Work Rules

17 FI17 - Hybrid Driveability and Stop-Start Fuel Strategy Boundaries

• FI17-L01 – Hybrid Engine Start/Stop, Torque Blending, and False Driveability Complaints
• FI17-L02 – Fuel Trim and Misfire Capture on Intermittent Hybrid Engine Operation

18 FI18 - Repair Decision-Making, Parts Replacement, and Verification

• FI18-L01 – Clean, Test, Replace, Program, or Escalate: Decision Logic
• FI18-L02 – Post-Repair Fuel Trim Verification, Monitors, Road Test, and Comeback Prevention
• FI18-L03 – Customer Communication, Estimate Language, Risk Notes, and Final Report

19 FI19 - Advanced Case Studies and Professional Mastery

• FI19-L01 – Case Study: P0171 Lean at Idle, Normal at Cruise
• FI19-L02 – Case Study: Rich Cold Start, Rough Idle, No Obvious Fuel Leak
• FI19-L03 – Case Study: Intermittent Hesitation Under Load With No Codes

20 CAPSTONE - Integrated Fuel Injection Diagnostic Cases and Professional Release

• Capstone Final Assessment and Professional Release Logic