got a problem

[drayrunner]

I changed the timing chain in my 02 3100 malibu, started up and run about 10 minutes then stopped had a check engine light, used my scanner and checked the codes, said crankshaft position sensor got a new one and changed it, run about 5 minutes and stopped another code another crankshaft sensor, also took notice when it was running the tach didn't work anybody have any insight on the problen. when it was running it was normal. thanks

[geoffinbc]

Your Crank and Cam position sensor could be out of Sync. Or did you forget to attach the wires to the cranks sensor behind the damper after you reinstalled the timing chain cover?. There are 2 crank sensors.