I have a 2004 Impala 3.8. Having an issue with it dying after so long. I’ve just recently replaced the head gaskets and all the gaskets that go along with that. Drove it for a few days, now, it dies after a few miles. It will start a knocking sound, then die. Replaced the pcv valve, was my first though. Took it to a repair shop to run a scan. Several sensors were bad. Replaced all but the o2 sensor so far. It’s not overheating, but, still starts to rattle and die after a few miles. It has everyone I talk to stumped. Any suggestions?
Ok, I know what engine and what year it is. I don’t know mileage, I don’t know what sensors were replaced nor any of the codes used determine that they needed replacing. I don’t know who your “everybody” might be or what their level of expertise is. Any mechanics in the bunch? So, flying blind here.
The rattle part almost sounds like oil starvation, loss of pressure shutting down the fuel pump so the car doesn’t kill itself. Is there enough oil? Enough oil pressure?
Take it to a repair shop that owns a scanner. That is, a computer that can chat with your car while you drive it around. If you can re-create the “dying” for the mechanic riding along, it is a good bet he can capture the data from the event to diagnose the problem.
Did any coolant get into the oil?
Crankshaft positioning sensor brother, if the shop said they replaced it make sure you pop the harmonic balancer off and verify or you will drive your self nuts trying to figure it out
Also why did you have head gaskets replaced these motors are certainly not known for having bad head gaskets sounds more like they told you your heads were bad in reality it was the lower intake manifold gasket that went, and of your upper as well causing coolant to slip into the rest of the manifold creating the previous issues , and depending on who did the work they probably installed. The new gaskets poorly causing a bad vacuum between. Block and intake . Turn car on and feel for suction on your oil filler cap
And just to verify u have a series 2 in there ?