I disconnected and cleaned the two grounds and checked the carbon tip in cap, it looks fine and ohm's clear to coil wire socket, including when tip pressed in. Rotor center contact to end point ohms out clear, cap seems ok to the eye. I had someone else verify good spark at coil but not at wire ends, he got same result. We find this rather weird, nothing is jumping out why its happening. Just have to wait and see what new parts do for it.
Thanks!
rj...

 

I got a third opinion and they came to same conclusion, it has spark from the coil but not at end of plug wires, and no obvious reason why?? odd.

Thanks!
rj..........

 

just a guess but could your ignition amplifier be intermittent?

 

Maybe I have missed something. Good spark from coil to cap, good spark out of the cap, no spark at end of wire. Do I understand that correctly? Because if I do, its the wire, regardless if they ohm out or not.

 

I have to agree, so I am waiting on new cap, rotor and wires.

As of ignition module cutting in and out, I checked voltages across the ignition module plug. All feeds to module are good where voltage is specified in the test procedure. And although it does not give specific ranges, voltage is rising and falling correctly on designated wires in regards to testing with ignition off, on and cranking. Hopefully its working correctly all the time.

Will report back after get new parts, fingers crossed!
Thank You!!
rj.....

 

The new ignition parts have fixed the problem and its running great. Thanks to all for the help!!

 

Amen

 

For what it is worth. My 1990 XJ40 stared with a very rough idle. A few seconds later teh idle returns to normal. Did all the usual things and the problem remained. My mechanic detected a clean cylinder head in No 1 cylinder and suspected a leaking head gasket. Having a more thorough inspection he detected a very fine mist in No 1 cylinder.
I Googled a solution and came up with K Seal. I read all the usual concerns and decided to use the product anyway. That was 3 weeks ago. Rough idle is gone, seepage in radiator overflow tank is gone. All is well until the next adventure.
In closing I noticed that my Owner's Manual (Yes the Jag still has one) states that when replacing coolant also include Barr's Leak. I wonder why that is?????.

Hope this helps.

TIG