I swapped a 5.2 out of a 99 Durango auto into a 98 3.9 Dakota 5 speed. I used the Durango PCM at first and it started up and ran for a few seconds then quit and wouldn't fire the injectors, only codes I got were for the transmission solenoid and range sensor which is to be expected since it is a manual. I plugged the V6 PCM in and it started up and ran, just not very well since it is only firing 6 injectors. I can get a PCM for a 98 5.2 Auto Dakota will that run it, I am thinking the Durango had a chip key which is why it wouldn't run in the Dakota.

 

A computer programmed for a V-6 is going to get seriously confused on a V-8. Crank sensor return signal is different.... so it gets confused right quick. You should be able to have your original PCM flashed for the bigger motor..... PCM is the same, programming is different. Did you swap the wire harness as well? Gotta have those two additional connectors for the injectors.

 

Yes, I know the V6 PCM isn't going to run it that well, and I don't want to use it because it is going bad anyway. I didn't swap the wiring harness, I just added the two injector wires.

 

That works too. As that is pretty much the ONLY difference.

 

Chip keys weren't a thing in 98/99 to my knowledge. But i cant think of what else that would cause that situation.