Greg,

Well I think I may have found the culpret today when I got home from work I did some tinkering with a couple of the things you talked about.

As I stated before 90% of the time it will start and only have a rough idle. I was messing with the distributor cap and wires by pressing on the boots of all the wires and the boot on the coil. It started and purred like a kitten. What made me think of this besides you talking about the above, was the fact someone asked me what the idle sounded like while it was struggling and when ya press the accelerator it would sound like a slight back fire sometimes, before it would die. Which a lot of the times id an issue with the distributor. I am thinking the distributor cap and rotor, along with new wires and coils should fix it. Yes?I was looking down trying to find the plugs and was dumbfounded. Maybe I was trying to look to hard for them. I think I saw them next to the injectors? Also thinking about re-routing the new wires. Good idea?
When it is running fine with no issues, there is a delay in the rev when pressing the gas peddle. Any ideas? Is that the throttle position sensor? Maybe it just happened to worj that time? Could that be my problem?

Key note: After the car was running perfectly fine for an hour, I turned it off to let it cool down. after 30 minutes it would still start back up. After an hour, it was fine. Then after 4 hours of sitting, it was back to rough rough idle and dieing.

 

Good work so far. take it one thing at a time and the problem will be eliminated. This is what I would do:
For certain change the cap, rotor, wires and plugs; gap the plugs to 25 thou very carefully. A touch of oil on the dizzy shaft and make sure the shaft can be turned a touch (15 degrees) and springs back. If not, work it back and forth and very sparingly lubricate it until it does.
Change the main coil too, you need a low resistance coil or you will knacker the ignition system. Buy the correct coil from a specialist Jaguar supplier. VERY carefully check the spade clips on the wires that go onto the coil. Quite often the copper wire fractures UNDER the insulation just where the wire goes into the spade itself. Not a bad plan to nip off the old spade and clamp on a new one on all the wires onto the coil.
Clean up the power resistor plug and socket, this can also cause some of your symptoms.
Now try it. It will certainly be better and the hesitation on the throttle may well have gone too. If not, or better but not perfect, then I would change the amplifier internal electronic thingy. These can give up if they get hot. I mean the piece labelled GM in the photo. Available from Rockauto etc etc.
All these parts would not cost more than 100 to 150 USD max, and would set the car up for reliability.
When all this done, I would be surprised if the problems are not solved. The TPS under the capstan is unlikely to prevent starting, it can give odd effects, but I would not look to fix that until all these other things are done.
Greg

 

Well these things you mentioned at a price for 100-150, I have looked and most of this stuff is around 100 each. Do you have links for this stuff for the 100-150 total? Also I need to find the trans kick down switch and the Fuel injection enrichment switche. The kick down switch on mine is busted inside on one of the terminals and the FI enrich one is all loose and worn out.

Also, I was wondering how hard the plugs are to get to? It looks like I have to take the intakes off almost. Shouldn't have to do that, or am I looking at stuff wrong?

I also noticed that my oil pressure is good, sittin at around 50 before it warms up, then it plumits to just above 0 when it is at running temp. wtf?

 

On Uk ebay there are loads available, some much cheaper than shown below, so with a bit of effort 150 USD is doable
12 plugs about 24 UKP
1 x dizzy cap about 30 UKP
1 x rotor arm about 12 UKP
1 set leads about 30 UKP
! x coil single coil modern type 30 UKP
Total = 126 UKP = 190 USD


I have bought a GM module from Rockauto for under 30 USD. So OK, maybe 200 USD total, or less with a bit of hunting and effort. remember there are lots of versions of the V12 and you need plugs and bits for the V12 HE Lucas ignition version. Be very careful to get a clear statement that the parts you buy are for this model. Check on the forum if you are not sure.
Do not worry about the kickdown microswitch for the moment or the full throttle enrichment switch; it will not affect the engine starting or hot running. Oil pressure dropping at tickover 100% normal, do not fret about that, either.
Plugs: they are on the inside of the V and tilt inwards at the top. Just follow the HT leads from the dizzy and you will find them. You do have to remove cruise bellows from the V to see them, also easier with dizzy cap off. ONLY JUST more than finger tight when you replace them, they are taper seating plugs, NOT crushable washer sort. You do NOT want to strip a thread in the head.
The point is on a neglected old car, replacing all these items is pretty important if you want it to function reliably.
Greg

 

Well I'll do some lookin and try and find all of that stuff and the microswitches. The one on the passenger side is kind of important I do believe in idle and coasting.

 

Mick
The microswitch on the throttle cable activates the gearbox solenoid that makes the box change down to second gear.
I think that USA cars also have a microswitch on the throttle capstan, that is thrown at WOT by the capstan. This makes the ECU go to fully enrich the mixture at WOT to guard against piston top detonation though too lean a mixture. If you are referring to another switch, post a pic, I can always be wrong!
If manually throwing the capstan WOT switch at tickover improves the tickover, then some other aspect on the engine is wrong.
Greg

 

Yeah I have both on mine. I went to my local auto parts store and they have the cap but not the rotor arm, so I am just going to order the stuff online from Britishparts online.

And yes those are the switches you and I are both talking about. In my pic here, you can see the kick down switch has a terminal busted off it, and the enrichment switch is not even in working order. It just sits there. You physically have to move the arm yourself because the spring or whatever is dead. I manually pushed the lever over to the capstan on the enrichment micro.

 

I decided to go out and take a look at the cap and rotor so I took the cruise off and set it to the side, labeled the wires and where they go on the cap. took the wires off and the vac line. pulled the cap and everything looked fine. No moisture and no hair line cracks. Cleaned up the points and put everything back together.

This is what it sounds like.... Someone said it is the tps with the up and down idle. Any thoughts?
<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf" flashvars="file=http%3A%2F%2Fvid35.photobucket.com %2Falbums%2Fd164%2Felectricjiles%2Fvids%2F20160415 _191729.mp4&title=">

 

I gotta tell you, my cap and rotor looked perfect too, new cap ='d no more problems. I'm not saying it's the same in your case but one problem with these is the rotor button contact IN the cap which is undetectable to the eye nor can you duplicate the contact tension vs spin the rotor puts on it.

 

I still ordered a new cap, rotor arm, and cables. When I pulled the cap I did notice the button was kind of stuck up in the cap. I had to tap it a few times to loosen it up to where it could push in and out again. Still ran like crap. How do you get the arm off? I need to know for when I get the new stuff in the mail.

Did you watch the vid? Did it act like your car did?

 

I can't get your link to work on my phone or iPad, hunting up/down is usually a vacuum leak (mine was the x-over pipe connections). Mine would idle rich, backfire, pop, run fine through revs in Park or N but idle and under load was horrid. New cap solved my problems. TPS is easy to check with a volt meter.

 

I should have been clearer, when my problem was up/down idle only it was the x-over pipe connections. My last idle, back fire, stumble issue was the dist cap

 

Mine is a crappy up and down idle with constant dieing. It actually sounds like its only on a few cylinders with up and down idle. When I try to give it gas while it is idling horrible, it pops and back fires without reving. If I unplug the coolant temp sensor it sounds better like it is on all cylinders but the idle is still up and down with backfire and no revs. just dies if pedal is held down to long.

 

when you unplug the CTS it should die straight away. Interesting.

 

Well in the video I posted is with the cts unplugged. It lets the idle be faster and when I plug it in, it dies. lol But I can restart it with it plugged in and the idle is low and crappy as well as up and down.

 

Also, I was wondering if this is the TPS for my jag.

 

Ok, so I was testing the TPS ranges... low end. .58 high end 4.45
I also went to look at the connections to the ignition amplifier. Noticed that the black connector was cracked... Pulled it out and it fell apart. Now It won't even start due to cross arcing between the 2 wires I think...

Does anyone know where I can get the wires that go to and from the Amplifier?

 

I also have a vacuum line issue. The distributor has 2 lines coming out of it. The one coming out of the top is fine- connected to middle of aav hose I do believe.
The one coming out of the side comes around to the left side fender well and oly has a small air filter on it. Where does the other end hook up to?
Also how much pressure does it take to move the fuel pressure regulators to open or close? I tried blowing and sucking on the hose of each one and couldn't feel a difference. Felt solid with no movement. Didn't feel like there was much vacuum from the other end either.

I have also found a reasonably priced ECU and was wonder if it was usable on mine. It is out of a '92 XJS.

 

The filter isn't connected to anything else. It just filters air that is drawn into the distributor cap by the other line you found.

 

There doesn't seem to be any suction from the hose/filter. Nor is there any coming out. Filter seems pretty clean as well.