I have a 2001 4.3L with a "W" code for a CMFI engine. I just bought this truck a couple months ago. Have been trying to get it running since. It coughs backfires and doesnt hold a steady idle and dies out when gas is applied. After replacing so many things (fuel regulator, crank sensor, distributor, distributor cap and rotor) it still will refuse to run right. The timing has been checked three times.
I never put two and two together to realize that the engine that was in the truck is an "X" code (CSEFI). So obviously the kid that had it before me put the wrong engine in this truck. My Question is how can I get this thing running? Would swapping the computer for a CSEFI computer get it to run right? Or do i have to put the right engine into it?
What should i do?
Any help would be greatly appreciated.

 

i personally have never changed out a 2nd gen engine without replacing it with the same (ie: swap out a 2.8 for a W code 4.3, like so many 1st gen's had done). i know that the pigtails for the ECM are different for a Z code, W code and the B code (2.8L), so i'm not so sure the ECM could be swapped between the wiring harnesses,plus the wiring would be different between the two systems.