Hi guys! I am new to this forum and i would like to thank everyone in advance for the help. Here's what happend. I have an audi A4 1.8t AEB engine with 5 speed gear box, i got the car 1 year ago and i had trouble with a missfire on cyl. number 3, I changed all 4 plugs for brk7e copper, and chipped stage 1 with intake and it ran fine for all winter.

Yesterday, I decided to test compression in all cylinders, because i had a gauge in hands and the time to spare, so i go ahead, unscrew all the plugs, put a LITTLE dip of full syntech oil in all 4 cylinders, unplug the injectors, and crank it to get 180 psi on all cylinders, good news right? Well not really, I put the plugs back in, start it and it ran good, until i get a p0303 code and flashing CEL , so i tried swapping plugs and etc, checked injectors, working, checked coils, working,so i said to myself lets put 4 new NGK plugs in there, bought new brk7e and gapped them to .030, and it still misfires on cyl, number 3!!! Its unbeleivable, i dont know what to do now my wife needs the car this week and it can't run on all 4 cylinders, it never did that before.

The only scary thing i can think of is a cracked piston maybe? or a non properly sealed valve? Because if its only intermitent ? it idles perfect, only when you push the gas pedal it starts to missfire. Guys i really need help on that one i have all i need to check and recheck i just need ideas for what to look!