Amount of timing advance correct?

My 98' XJ is still plagued by running hot. Even after a Hesco water pump and aluminum radiator (from the 3 core brass/copper). So I plugged in an OBD-II scanner to see how everything looked on it. From what I can tell everything was spot on, O2 numbers looked odd but had good voltage, STFT (5 to -.8) and LTFT (7), temps were all within reason.

The confusion comes in with the timing advance. It showed 18 deg. at idle and 27 deg. with it floored. But just cruising down the road at 60-65 in top gear on flat ground the timing was 40-45 deg. and then would drop to the mid 30's on slight grades. This seems way to high to me, and the opposite. I thought the timing would advance more at full throttle and the higher the rpm, and less when cruising under light load/low rpm.

Anyone know if this sounds right, or is my computer messed? I know that an engine with to much advance can run hot, and my plugs have the vaporized metal droplets on them to prove that it is. Can't find the info anywhere and the mechanics at the dealer ships and my local mechanic don't know.

Thanks

Is that your downstream O2 sensor stuck on 7?

The advance looks normal to me. At cruise, more advance can be used for good economy but when a load is encountered some advance has to be trimmed or it would ping badly.

Have you ever considered a clogged catalytic converter?

cruiser54 said:

Is that your downstream O2 sensor stuck on 7?

The advance looks normal to me. At cruise, more advance can be used for good economy but when a load is encountered some advance has to be trimmed or it would ping badly.

Have you ever considered a clogged catalytic converter?

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Cruiser54 is correct based on what I see on the Scanguage. The 4.0 at idle and running with load eg: going up hills, the timing is lower. Part trottle cruise would vary between 25 and 35 degrees +/-. De-celeration like taking your foot of the gas while going down hill, it could go as high as 50 degrees.