IQA Codes are entered into the ECM to improve control of the injected fuel quantity. The code applies over the entire programmed fuel map. The classification codes compensate for deviations in metered amounts, and make fuel quantity metering more precise. The adjustment codes also increase injector efficiency on the engine and improve emissions.
Various engine manufactures call them Trim Codes, Injector Calibration, Injector Flow Rate, Injector Classification Code, Injector Correction Code, Flow Rate Programming, and Injector Delivery Compensation. No matter what the OE calls them, IQA (Injector Quantity Adjustment) help emissions and drive ability.
Some later Cummins applications with Bosch injectors use a different method to calibrate the injectors to the ECM. They use a process called “Zero delivery calibration”. This works by injecting a small amount of fuel into one cylinder during overrun conditions (on deceleration). The wheel speed sensor detects the resulting torque increase as a minor dynamic change in engine speed. The increase in torque is imperceptible to the driver, but is clearly linked to the injected fuel quantity. The process is repeated for all cylinders at various operating points. A teach-in algorithm detects minor changes in pre-injection quantity and corrects the injector triggering period for all pre-injection events. The teach-in adjustments ensure a constant level of emissions in the lower end, part load range, for the service life of the vehicle.
Injector Quantity Adjustment codes are located in different locations on the injectors. Some rebuilt injectors will have IQA codes on the box or the bag it is packaged in. Be certain to note the code and the cylinder you installed the injector in, and enter them into the ECM.
If your scan tool has not been updated recently, you may run into an issue entering IQA codes, because the latest codes are not listed. We have also encountered the situations where the ECM has an update that must be performed, in order to enter the new codes.