Nubby is correct. The timing isn't adjustable on the 2.5L MPI engine. The ECM does the adjustment on its own. Actually it is adjustable just like any other engine, but you need an engine analyzer machine to hook it up and get it set correctly. Just one of those "better ideas" that they had to make things harder to work on if you wanted to do them yourself.
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...