4.0L Ignition Timing

Searched for about half an hour trying to find timing marks on my 99 4.0L. Then I googled and found a cherokeeforum.com thread which said the 4.0's ignition timing isn't adjustable (computer controlled), and therefore no need for timing marks.

Is this true?

Yes it is true. Only time the timing mark is used is for timing Chain, crank and Cam alignment to distributor and TDC checks. The computers completely control timing on the 4.0 XJs since 1987. The distributor does need to be indexed when installed!!! But the rest is all electronic.

its true , the computer and the crank sensor do all the timing adjustment.

Incredible.