Hi, n7kme...Ignition timing on a Jeep electronic fuel-and-spark management system, including 2.5L TBI, is fully a function of the ECU and its sensor signals.  The distributor is simply that:  a way distribute spark to the plugs.  All spark timing and fuel supply functions are computer (ECU) controlled.   The only spark timing verification is base timing.  The procedure for setting base timing is in the factory data below, although this factory data makes an erroneous reference to hooking up th