Bosch Fuel Injection and Engine Management: How to Understand, Service and Modify

• Motronic
• LH-Motronic
• L-Jetronic
• LH-Jetronic
• KE-Jetronic
• KE-Motronic
• K-Jetronic
• D-Jetronic

ACCELERATION

Any time you press the accelerator, opening the throttle increases manifold pressure which in turn increases intake air flow. The fuel system, responding to this increase in air flow, meters additional fuel to maintain the correct air-fuel mixture.

Accelerating - opening the throttle very quickly - places additional demands on the system. The sudden transition from closed throttle to open throttle produces sudden spikes in manifold pressure.

The fuel system responds quickly to these changes, but not instantly. Some additional fuel delivery capability is required to compensate for these changes in manifold pressure - to prevent stalling and produce the quick throttle response we have come to expect and demand.

For quick, smooth throttle response under acceleration, the basic system of air flow sensing and fuel metering is too slow. The fuel system must be able to instantly compensate for rapid increases in manifold pressure with additional fuel.

In many carburetors, additional fuel is supplied by the accelerator pump. It mechanically squirts additional fuel into the intake air stream whenever the throttle is opened suddenly.

As you will see in later chapters, fuel-injection systems employ various methods of acceleration enrichment.

BOSCH FUEL INJECTION-AN OVERVIEW
Introduction | Fuel Injection is Here | Fuel Injection Types | Engine Management | Bosch Jetronic Family Tree | Applications

ENGINE MANAGEMENT FUNDAMENTALS
Introduction | Basic Factors | Operating Conditions and Driveability | Emission Control | Control Systems

PULSED INJECTION-THEORY
Introduction | L-Jetronic | LH-Jetronic | Motronic | D-Jetronic | Digifant II

PULSED INJECTION-TROUBLESHOOTING AND SERVICE
Introduction | Troubleshooting | Fuel Supply | Start and Warm-up Testing | Air-Flow Measurement | Idle Speed | Mixture and Lambda Control | Motronic Timing and Dwell

CONTINUOUS INJECTION-THEORY
Introduction | Air-Flow System | Fuel System | Fuel Metering | Control Systems, Vensations | KE3-Jetronic and KE-Motronic

CONTINUOUS INJECTION-TROUBLESHOOTING AND SERVICE
Introduction | Troubleshooting | Air-Flow Measurement | Fuel Supply | Control Systems (K-Basic, K-Lambda | Control Systems (KE-Systems) | Idle RPM and Mixture | Start Auxiliaries

TUNING FOR PERFORMANCE AND ECONOMY
Introduction | The Legal Issues | Driveability | High Performance Basics | System Basics | Air Flow Improvements | Knock Sensor | Tricks | Racing Applications | Radical Injection Systems | Suppliers