Pontiac Repair: swapping engines, 1990 chevy lumina, chevy lumina

Question
I have a 1990 chevy lumina with a 3.1L automatic, i blew the motor in it and replaced it with a 1989 pontiac 3.1L, I have spark and fuel and my firing order is from L-R back of the engine 1-3-5 and from L-R in the front is 2-4-6 with coil pack order fromL-R 1-4-6-3-2-5 but it acts like the firing order is off. Was wondering do i have to switch the computers also or what is going on? Please help...Thanks for everything

Answer
Hi Jason:

those 2 engines should match up okay. Did you swap over the electrical components? for just the whole engine with the harnesses? If you swaped out a complet assembly make sure the wires in the harnesses match just because they all plug in doesn't mean that the wires are in the same spots. meaning a chevy and a pontiac may not be the same also being 1 year apart is an even better chance that something is different. I would swap over all the electrical components from the pontiac engien onto the new doaner engine and see if it runs then. Also the emission label under the hood will show you the proper orientation of the plug wires on the coils. That was nice on the older cars. the new ones do not have that. Hope that helps you out :)