Hi. I have an Astra with a 1.6 turbo engine and an ME7.6.2 ECU. The injectors were scaled from 285cc to 613cc, the MAF from 70mm to 80mm, and the MAP from 3 bar to 4 bar by a mapper. Piper Cams Fast Road series camshafts were then installed.

However, I feel the engine is running rough/misfiring at idle. Furthermore, idle fuel consumption has increased by 0.4 L/h. The AFR fluctuates constantly between 14.6 and 15.2. The STFT correction seems to be stable at 0. The airflow is around 13-17 kg/h. However, the ignition timing fluctuates constantly between 6-20 degrees at idle. The throttle position is fixed at 1% at idle.

Basically, I believe the ECU is unable to control idle because the throttle has reached its minimum limit and is using variable ignition timing for idle control. I might be wrong. When I checked it in Winols with the best map package I could find, the KRKTE and TVUB values ​​seem to be calculated well. What do you think the problem could be here?

Mapping was done after the camshaft installation. However, when we tried the same mapping on an engine without a camshaft, the misfires disappeared, but the high fuel consumption at idle continued.