Can one of you tech guys please tell me the name of the odd looking distributor system in these cars. I have not seen a name in my Jag manual or the electrical
supplement for the '95-'96 cars.
Thanks for any reply, RagJag

You should have "COP Ignition"---Coil On Plug Ignition.

Each spark plug has its own coil. There is no distributor.

Cheers
DD

Yeah! What he said.......

I'll add that the "distributor" you are referring to on your car is actually a Cam Position Sensor. It just resides where a distributor WOULD be; since you are a COP ignition, there is no distributor.

An added note is that the engine will run without the Cam Sensor connected, it will just have to crank three or four times as long to figure where #1 is and start.

Cheers,

I took this car to a local mechanic that works on Jags. A 73 year old man that has the largest collection of tools I have seen in my life. He tested for my miss at idle on an expensive OBD 2 code reader. #3 plug showed a miss. Do any of you guy know the best replacement for coils for this car. Several aftermarket brands and also the Belk Arnsley are available. Are the Jag ones best. I am going to replace all six and the plugs at one time.
Cheers, RagJag

Avoid Beck Arnley

This thread will give you some sense of the coil dilemma

https://www.jaguarforums.com/forum/x...0-coils-93966/

Many other threads on the topic are in the archives

Personally I'd avoid replacing all the coils. Or if you do, save the old ones as spares....as they might come in handy, given the iffy quality of replacements.

Cheers
DD

Replaced all 6 spark plugs and 6 coils. No change in the idle miss and dying. Idles at 600 rpm which is correct by my manual. I am wondering if the idle can be set to 800 rpm instead. The engine seems to run fine at that setting.
I am looking at the idle air control as the next possible fix. I do not have manuals that give testing info for any of the devices on the engine.

My local Jaguar dealer just informed my yesterday that they will not even do an OBD diagnostic on a car older than 14 years. I expected that but still it is disappointing.
There are no check engine lights on. The bulb is good, for it comes on when starting.
Thanks for any help with this problem.
RagJag

Spray some starter fluid around the throttle body, intake manifold and the intake boot and see if you have an air leak. Unmeasured air will cause a rough idle and not illuminate the Check Engine light.

I will try that Roger. I would expect the engine to speed up from idle if unmetered air is being drawn into the intake manifold and I introduced starting fluid. The engine seems to be loading up or getting too rich a mixture at idle.
I still need to know how the idle rpm is adjusted on this engine.
Cheers, RagJag

Roger, spraying starting fluid around the intake structures had no effect on the idle rpm. Unplugging the idle air control also had no effect. I unplugged the MAF sensor with no effect. I don't know if the MAF would be doing anything at idle but the IAC being unplugged will make an engine die, in my limited experience. Of course this is my first Jag, so I really don't have any experience.The car is driveable after the plugs and coil swap out. If any of you folks out there have a 4.0 and can chip in, please do.
RagJag

I am disappointed to say the least. 200 views of this thread and only 7 replies. This leaves me no option but to keep throwing parts at this beast until I hit the failed one. IAC and then MAF censors are next. Don't want to even think about a used ICM.
Not happy with Jaguar dropping these cars, either. Ford did that with a 1997 Mark V111 that I owned a few years ago. It was only 8 years old at the time. I promised myself, no more Fords.
Cheers,
RagJag

Can you try another dealer?? I don't know why they should completely cut of cars of this age. I'll let them take in any older cars as long as it's not a clapped out hulk. If it's in decent shape and the owner will be good with Jaguar parts and methods, I'll take 'em in. I think they should, too.

With all that car has been through, it would be a good idea to find a dealer that still has a working Jaguar PDU and have the "Adaptive Terms" and throttle adaption reset. That zeros out the fueling adaptions that can go astray when it's running bad. Sometimes that's all a car needs to make it idle right.

Good luck!

Oh my xjrguy, please come to live in Richmond! My '96 is a beauty and I would really not like to give up on her.
I will look for another Jag dealer in Richmond, VA.
Cheers, RagJag

Spend a couple of days north in DC.

I have had good luck with Top Line Jaguar in Springfield, VA. Make sure you call ahead and schedule some time.

You may have to leave the car, but they are very familiar with these old cars. They also still have the necessary tools, including the old PDU.

Having installed a new Idle Air Control valve, I have no improvement in the missing and dying at idle. The ECU does not seem to be sending any signal to the valve. I will get a digital multimeter to test the wire continuity from the ICU to the valve.I have the Kirby Palm 'Jaguar Help' downloaded in my computer. This version was updated in 2009. Is that the last update?

Someone mentioned the Jaguar diagnostic system called PDU but Mr. Palm's mention of it says it is not good. Do the 1995 and 1996 XJS need this system for diagnosis or do the OBD11 devices work on these cars instead.
Cheers,
RagJag

Wow.

Sorry I have missed this thread. The forums are here to help each other out. My XJS is getting repainted and I have been busy sorting my "new to me"'X type out.

Is the car over fueling ? Backfiring? Does the problem come back and go away? Any codes?


Based on my experience with the AJ16, your symptoms indicate

1-Throttle body filthy and gummed up-car is notorious for this
2-Bad or dirty EGR valve
3-TPS is gone (based on your symptoms, less likely, but still possible
4-water on the ECU (very common on the AJ16 cars-water drips and destroys pins....if there is no gunk and all your pins have resistance to presure, coat them with XG Motorcraft synthetic grease. It's designed for ECU connectors. Don't use dialectic grease)
5-if you have installed aftermarket coils that do not have "made in Japan" stickers on them, you just added another variable. Also make sure your coils are connected properly. People have a ugly habit of mixing up 5 and 6

I would immediately look at those first 4 things.

Mark, thanks for the reply. The engine runs well except when I stop and it idles. It immediately starts to miss and will die if I don't apply a small amount of throttle. The problem does not go away and is consistent. No codes. Check engine light works when starting but does not come on later. Disconnecting the old or new IAC and/or the MAF has no effect on the idle. Does not backfire. It is immediately running very rich when I let it idle but runs like a bear just off idle and on up.
I cleaned the throttle body but was unaware of the EGR possibility. Stuck open would affect the idle, right? Wouldn't that cause a lean condition at idle?
How could a person 'mix up' coil #5&6? as they are identical.
I will check the ECU for connection issues.
RagJag

Where exactly is the ECU located?

The coil connectors are what get mixed up. People plug them to the wrong coils.

On the passenger footwell

I've been following this post for some time. I unfortunately have the same problem also. I've had it for over 2 years, I purchased the Jag. with it, so I really never drove without the problem. I have a 93 xjs and have been throwing money after money into trying to find the solution to the idle issue. I've replaced the the ecu, maf, cold start sensor, etc, etc, and had all the electrical settings recalibrated at a repair shop (professionally). They were the one who reset all my settings to specs and then told me that was the best they could do unless I wanted them to purchase a new maf and ecu from jaguar, for a small fortune. Considering that it was running fine except at idle, I decided to buy a used Maf and Ecu, as I truly doubted that was the issue. As expected, after replacing both, it did not improve the idle issue at all (more money spent and still no solution)
After all the spec settings by the foreign car shop, it ran worse then before at idle and now upon throttle, it would boog. So I reset them to by sound to my original settings and it runs good off throttle, but still runs rough and rich at idle, but doesn't die at a stop.
Anyways, I wish I could tell you something to do to solve your problem, but I have just about replaced all major components and possibilities and had the engine set and reset several times to try and solve this idle issue. The only difference is my engine, it would run rough at idle, but never really died at idle.
My only suggestion is to use the idle bypass valve (I think that is what its called) located on top of the intake manifold and uses a medium size allen wrench to adjust the screw and try to increase the idle slightly. Don't turn the screw to much cause, I did find out that if the air sensor is changed to much, the ecu overrides it and resets the idle back to it's lower setting.
After 2 years of trying to resolve this problem, I've kind of gotten used to the rough idle and because it doesn't die out, I've just learned to live with it. Good luck
Good luck and I will keep following this post for a possible solution