1991 Plymouth Sundance Swapping my dead 2.2 for 2.5

The engines are basically identical, but the 2.5L has an extra balance shaft to reduce normal engine vibrations that you feel. The oil pans will be a little different.

The question is if the original Engine Computer will run the new engine. The larger engine needs more fuel. That will either be done by using an injector that flows more fuel, or by using a computer programmed to hold the injector open longer during each pulse.

Okay, so I should definitely get a different computer then? Or would the injector be the cheaper option? I am on a student budget so the cheaper the better lol.

Student, huh? I spent nine years telling my students, "what you heard is not what I said". I don't know if the new engine will run just fine with the old computer. I DO know people are switching from the 2.7L to the much better 3.5L on newer Chrysler products and the same computer can be used. Chrysler has always been famous for excellent parts interchangeability between years, models, and engines. That is the original reason I first became a fan of the company.

When I worked at the dealership though, we never got involved in things like this. You usually won't find a mechanic or a shop willing to change engine sizes either because emissions laws come into play. In this case, once the engine is running properly, the emissions will likely be the same as when it was in its original car, but it will not match what is on the sticker under the hood. That's where the over-eager, idiot politicians have their noses stuck, (up your tail pipe), and have made life miserable for us.