LH 2.4 and EZK116K — information and adjustments

Although LH 2.4 was designed back in the 1980s, it is an adaptive and surprisingly advanced system for its time. When tuning, however, it is important to understand its technical limitations, especially regarding the air mass meter (AMM).

You cannot. Whenever you change the air mass meter size or injector flow in B200/B230 engines, it requires corresponding changes to the engine management software (so-called tune/chip). The system cannot automatically scale fuel delivery correctly if the physical components change significantly.

LH 2.4 uses Bosch HLM2 series meters (e.g., suffix -016). Unit: Measurement is based on air mass flow, measured in kilograms per hour (kg/h). Voltage: AMM output voltage is in the range 0–5 V. Reference value: In a B230 engine, a clean and functioning AMM output voltage at idle is approximately 2.3 V (tolerance +/- 0.1 V). If voltage deviates significantly from this, the meter is dirty or defective.

The standard -016 suffix meter reaches its limit (approximately 5 V) surprisingly quickly in turbocharged engines: B230FK/FT: At approximately 1 bar boost pressure, the meter is "maxed out" after 4500 rpm. Beyond this point, the meter can no longer tell the control unit about increased air flow, which means the mixture can become dangerously lean without proper tuning.

LH 2.4 is a so-called bank injection system, which means the following: It injects fuel twice per revolution from all four injectors simultaneously. Injection quantity is controlled by adjusting the injector opening time. Standard injectors are scaled so that at maximum load and RPM, their duty cycle is approximately 80%.

No, it is not. The AMM is nonlinear, meaning voltage increase does not correspond directly to air flow increase in a linear ratio. For this reason, inside the LH control unit there is a separate linearization table that converts voltage data into true mass flow.