Runs rough after replacing Crankshaft Position Sensor

[moovinfast]

2004 Audi A4 1.8T Avant Quattro automatic

Car would occasionally crank several times before starting. And would occasionally get codes for random misfire and misfire on cylinder 1,2,3,4. But still ran fine. New Coils and plugs didn't solve the problem.

Today we replaced the cam position sensor. Started the car and it ran fine. Decided to also replace the Crankshaft Position Sensor. After replacing the crank sensor, it now runs rough with audible misfires and wants to die while at idle. No Check engine light and not throwing any codes with my cheap OBD II reader. I bought a second Crankshaft Position Sensor locally and we reinstalled it, thinking it was caused by the cheap Crank sensor. Same issue. I can have access to Ross-Tech if needed.

What do I check now? Does the new Crankshaft Position Sensor need to by synced somehow? Could something have been knocked loose while removing the old Crank Sensor wire? We replaced the coil pack wiring harness a few years ago due to brittle wires after it wouldn't start one day.

[EuroxS4]

Use VCDS to check all relevant MVB. Your original issue sounds like a bad FPR in the fuel filter or leaking injectors. But now with the parts cannon loaded who know what brand and quality parts were installed. Start with the brand and quality of the parts replaced first.

[kwilson]

Did you knock off a large vacuum hose or something while working under the intake manifold?

[Cybersombosis]

Put the original crank sensor back in since it ran fine before you changed it out? Or did you cut the wire to get it out?

[Gin+]

Sounds like a vacuum leak causing your current issue. Crankcase vent elbow would be my first suspect.