POLO 6R 1.2 69HP - EPC - ABS - FLAT TYRE + SHAKING + BACKFIRING

[Amer99]

I drive a 2012 Volkswagen Polo 1.2L petrol. I bought the car two weeks ago, and it was running normally with no major issues, except for a chain noise during cold start-ups. ( Car didn't shake here and didn't go into limp mode )

After not driving the car for a week, I tried to start it, but it wouldn’t start at all. If it did start, it would immediately stall. I replaced the complete timing chain kit, along with the oil and oil filter. After that, the car started fine and ran smoothly.
The next day, I tried to drive, but after pulling it out of the garage, the car started shaking. When I checked the car’s diagnostics, it showed a misfire on cylinder one, and sometimes on cylinder two as well.

I took the car to the shop and replaced all three ignition coils, all three spark plugs, and the fuel filter. After starting the car and doing a test drive, the issue returned. We did a compression test on the cold engine, and the results were: 6 BAR for cylinder one, 12 BAR for cylinder two, and 16 BAR for cylinder three.

I went back to the garage, and they replaced the inlet valve on cylinder one, as well as performed all the other necessary repairs. Now, the car shakes slightly when idling at low revs. When driving or revving the engine, the car runs fine, but at idle (under 1000 RPM), there’s still a slight shake.
After driving for 20-30 minutes, the check engine, EPC, ESP, and tire pressure warning lights come on, and the car starts shaking more violently and becomes sluggish + backfiring. I have to stop, turn off the engine, and wait 5-10 minutes. Once I restart the car, the warning lights disappear, and the shaking calms down, though it still shakes slightly.

When the mechanic runs diagnostics, it shows a misfire on cylinder two. Since the spark plugs and ignition coils are new, they shouldn’t be causing the problem. We also checked the fuel injectors, and they seem fine.

Compression test after inlet valve chance on cylinder one:
16 BAR for cylinder one, 12.5 BAR for cylinder two, and 16 BAR for cylinder three.


Does anyone know what might be causing this issue? Any help would be greatly appreciated!