My guess is one of your coils is a) bad b) surrounded by oil c) needs a new spring or d) the connector or wiring is flakey.

All my aftermarket went bad in one year, but one of my japan coils was bad out of the box....

 

Mark,

a. New coil is on the way. I will do the musical chair game with the coils I have now.

b. I will check for oil along the way. I have replaced the camcover and spark plug gaskets a while back. I checked it one time and they were all dry. Obviously, the musical chair game will give me a chance to do a second check. I will look at spark plugs too... one by one.

c. I happen to have a couple of spare springs... I will stretch them out as I move them around. Good suggestion.

d. If all else fails, I will make a new harness myself. I should have the time to look into that this weekend. I like the idea of that.

 

A couple of my coil connector where bad, and I figured it out by wiggling them while the car was on . It's a simple ford/Motorcraft pigtail you can just solder.

Actually just references sake let me post some AJ16 pigtails that are available brand new on the Motorcraft connector catalogue :

For the AJ16 coils its WPT 767
For the AJ16 inertia switch it's WPT 414
For the AJ16 MAF SENSOR it's either WPT 4771 or WPT 535

Even if they change part number that should give us a good starting point to find the right connector .

And the reason I know is because, like I said my coil connectors failed (2 of them) and my inertia connector was so flaky it was causing the car to die at speed bumps. Solder new connectors and problems solved. The MAF I just bought to have around since it seems like that connector sits in a awkward possition in the car and it's only a matter of time.

 

I believe I solved it on my second try. Coil #2, although new, was apparently the culprit. The dip in idle and voltage every 32 seconds appears to have gone away.

I will hold on to the failing coil to keep as an emergency spare. Although not ideal, it should get me out of a mess should one of the other coils fail completely.

Thanks for your help Mark.

 

I am glad it was just the coil, it sounded like it with that rhythmic "drop" in the idle. Did you buy all your Japanese coils from the same source? Maybe they have warranty and you can exchange the faulty one.

 

It ended up not being the coil.

I swapped out each coil, one by one, replacing the one I took out before moving to the next one, and I could not get the problem to go away.

Cylinders #2 and #3 seemed to want to work the longest, but it was almost as if the car relearned to dip later. It could have been the warmer weather as well.

Anyways, I think it might be time to open a new thread instead of keeping this one going...

 

Just thought I'd tie this thread up and point to the thread I opened based off of this one...

https://www.jaguarforums.com/forum/x...4/#post1157908

 

Always fun hunting for solutions

 

RagJag,
I don't think our 1996 4.0 xjs has this.
Cybercg,
What year is your XJS?