Real emergency. bad misfire issue.
 

Im stranded in my home state. Its Upstate NY. I slipped into my yard and got stuck in mud. slid around despratley trying to get back onto the driveway. and let it idle because my ignition switch is faulty.... it idled got rough and quit.... next time it started after I got pulled out it was ideling super rough and limeted performance... Checked codes and 351 352 and 1000.. later on 353 and 354 added. did the old fashioned unhook the coils unhooked c1 and c2 and yeah no change ordered coils changed plugs and no improvement. And im talking coil nearest airbox and one behind it. I got some funky voltage while its running but not like the other coils. pull other coils it gets rougher of course. Ive been forced to drive it a bit. It shutters at 55+ im sure due to misfire. Plugs were black but dry in the bad cylinders.... Wheres that relay and how do I trace the wires could they have unhooked. note: the vac hose melted I have repaired it but I think that was due to raw fuel burning in the manifold and heating it. Need help asap I gotta drive this thing home ASAP got a sick woman at home... work bla bla 1400 miles away.:icon_brr:

You might want to add what exact model, year and engine you have before the rush hour starts here so that someone can give you immediate help without having to stop to ask those questions.

Sounds like the electronics might have been fouled with mud or water with all the slipping around. British electronics, perhaps more than others, like to be clean and dry.

Not the most helpful response, I know, but perhaps something worth considering.

well its a 98 ... xk8 4.0l ... I get a weird voltage... I really need an idea. I need it fixed asap. I really have to drive that car asap. Its an emergency boys. Ill be giving the same if I could help with any of it but this jags throwin me some nasty curve balls last time it broke down I was in lauderdale and the wires melted to the fuel pump... a new one.

There is a separate ignition power module for each engine bank.

It is a box located in the bulkhead, one on each side.

My guess is that like your A side module has crapped out from your description. It is Jaguar part number LJA1450AF and lists for $459 at the dealer. The relay powers both A and B sides, so if it was bad, I would think the other bank would be failing also.

SAved by some local hick at a two bit shop!
 

Whoever this joe blow was I gave him five bucks. I was looking for this specialty shop owned by an xk8 driver. I got lost and ran into this nearby shop. Some dirty mechanic (like myself) came out to greet me and I asked if he knew where this shop was and he hadn't a clue. I asked him to take a quick look and before he did he said : Wonder if the harness got burned. I mean an erratic voltage... I took off the air intake tube and sure enough he pointed and said Ill say its burned! All eiight were melted togeather on the ends and burned bare in the middle! Its a wonder I didnt fry something. 18 guauge wire and some black tape later she roared to life and some nasty stuff shot out of the passenger side pipe. I believe proper would be 20 gauge but it will get me home, Im off tonight to a 1400 mile trip. Changing oil and tires first. still need sway bar bushings a heater valve or core and bondo. Then ill snap a pic as of now its got a big dent a taped headlight whipped interior and 2 bald tires. not worth pictures. Thanks guys.

Good luck on the road! It's amazing how often the problem is in wiring or a simple mechanical failure, isn't it?
Yet, like you, I often get caught up and first think of the expensive modules.

Around the world.
 

The jag has put a grueling 4000 miles on since and is in maryland. The wire is fine and I have left the covers off the coil packs because I plan on re doing both harnesses because they are cracked and aged due to miami beaches salt air pummeling it. I got bad sway bar bushings I might make a pair but if I could find poly it would be cool. anyone know why my front end would be sitting low. with low profile front tires it scrapse sometimes I would really like to tune up the suspension at least drop the back but I get stability controal fail message. Is that air asist suspension?

most often, the sagging is primarily a result of the upper shock mounts deteriorating. They have a rebuild kit you can get using poly, and there's a few threads on the subject around here. Otherwise, rubber mounts can be had from the dealer.

There was one member, if I recall correctly, that was scraping, and even after the upper mount replacement, it still was too low for his liking, and last I remember, he was considering new front coil springs.

In rebuilding my front end, by simply replacing the aged Bilstein shocks with $100 Bilstein HD units, I gained a half-inch of height and a better ride. My mounts had already been replaced much earlier.

FYI, if you continue with your suspension questions, please start a new thread, as this one has strayed from the original intent and subject.