bmw e90 n52 no spark

Question by raymonddiamond posted 1 month 3 weeks ago in BMW

hi i just started a autoelec workshop ,i need help on bmw e90 n52b29AE .the fault was no spark,i replaced 1 ignition coil .i tested signal wires from dme for supply (VOLTAGE IS OKY)I CHECKED THE 12V ITS CORRECT,I CHECKED GROUND ,ITS CORRECT.2.i checked all fuses under bonet for cam and cranck sensor ,it was correct .when i replaced and tested all 6 coils the car started but idel very bad,it reved up but misfireing .now again theres no spark.i once again tested for 12v+supply aswell the signal from dme,its correct.theres no spark from coils why