Injector volume adjustment
The injector volume adjustment (IMA) is a procedure for the precise determination of the quantitative injection behavior of an injector .
Precise metering of the fuel to control the combustion process is very important, particularly in order to meet the high demands on the exhaust gas values of modern diesel engines.
The injection quantity of the individual injectors is determined immediately after production, as this varies slightly from injector to injector despite minimal manufacturing tolerances and thus leads to deviations in the throughput. The characteristic behavior is stored in a six to seven-digit IMA code , which is saved on the injector or printed out. Before using such an injector, the engine control unit must be told which IMA code was installed on which cylinder. The control unit then takes these values into account for individual control.
Together with the zero quantity calibration , the IMA code laid the basis for precise control of the injection process.
Incorrect coding (on the injector or in the control unit) can not only lead to poor exhaust gas values but also to uneven engine operation. When cleaning IMA-coded injectors, it is therefore essential to observe the installation sequence or to recode the control unit.
The IMA code is at EURO4 motors 6-digit, at EURO5 engines 7 digits.