Hi all

I have a Jetta (2012) 1.4tsi CAVD currently clocking 189000km. A bit of info before I get to the issue this car had an engine and transmission replacement at 75000km under warranty according to the dealership it's an updated version of the engine, but now that the warranty is well over the misfires from my obd2 scan is giving me the jitters.

All started with a usual cold vibration, so I used the obd 2 Wi-Fi scan tool to scan the engine, results shown several counts of misfire in cylinder 1. No Check engine light No trouble codes either.

Suspecting it could be bad coils or plugs I switch them around I found that spark plug in cylinder 1 had black soot on it and the tip looked a little bent and so I changed it with a new piece. I ran the scan code again and cylinder 1 still shows 5 counts of misfire still no check engine light nor fault codes.

I do know the the car is not running as it should for at times it's really smooth and sometimes it's rough when it idles too there's intermittent vibrations and when accelerating it's feels like its pulling back.

Next was to bring over to a garage they too were surprised that their scan tool didn't pick up any misfire, so proceeded with a compression test and results were 12 bars (170psi) across all 4 cylinders. At a lost they decided to change connectors to the coil packs as the plastic clip were broken. After all that I ran obd 2 again and still shows cylinder 1 misfire and still no check engine light and no fault codes though my fuel consumption has deteriorated and cold start vibrations are still bad.

I would appreciate any advice given to resolve this mysterious misfires thanks

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