Gotta ask . I'm swapping out my low k 5.2 for an even lower K Mopar reman 5.9 (12K). I do intend to get a tune for it down the road and I know my PCM will suffice for now , but , just wondering what's gonna happen when if I swap in a different PCM .

I do have a stock 1998 5.9l Grand Cherokee PCM . It's OEM tune is a timing tweek that requires premium fuel that I run anyways . It's a plug in swap , also ran a 46RE (normal stock shift points) . I'm trying to think why this won't work and I can't really come up with a reason why it wouldn't .

Not a big deal , but it would be a cheap way to compensate until I get my tune . The engine is dressed with an M1 , 52mm TB , and headers have been ordered . Thoughts ? Ever been tried ? Worst case scenario , it doesn't work , and I swap in the original PCM ?

 

The GC PCM is going to have security stuff that won't work with your truck. You might be able to swap in a 5.9 PCM from another pickup but that is also up for debate. You are going to need a tune right away with the M1, headers & 52mm TB. I think you will be running way to lean with a 5.2 PCM. If you were installing the 5.9 stock then yes you can get away with running the 5.2 PCM.

 

I think your right about the security issue . Mine doesn't have it , so , even a donor I would have to be careful with . I do have the BCM also but not sure how that would react with the non digital display on the 96 . Yeah , no sounding like it's worth the effort .

I also heard back from my Tuner guy . He said it will run on the original PCM for now , and drive fine . He knows the mods on there . However , I have decided to order the tuner . No sense in doing all this work and not making the most of it . $535 + shipping and crap .

 

Too much changed in the PCM from 97 to 98 for that to work in your 96. The tuner is indeed your best bet.