My '88 XJS has always started up and ran smooth until I drove it home one day, parked it under cover, and when started again a couple of weeks later it ran so rough I thought it was going to shake the car apart. This was nearly 2 years ago. This car has Lucas ignition system and I was advised at the time to replace the distributor cap and rotor to avoid a potential engine fire if either Bank A or Bank B was faulty. Since that time, other than keep the car under cover and protected, nothing has happened to solve the problem. During that time I also checked that fuel in the tank to confirm it wasn't rotting and smelled fresh (it still does).

Fast forward to this past weekend.

1. I replaced both the distributor cap and rotor. The old ones look good but I replaced them anyway,
2. The car started right up, running like 1 cylinder might be mis-firiing a bit and it ran for about 10 seconds before it quit.
3. I tried a re-start and it ran up to about 1000 rpm, running almost smooth yet it died again.
4. The definite smell of a rich exhaust
fuel mixture was in the air.
5. I also started smelling raw gas vapors.
5. I cranked it over one more time but couldn't
get the engine to fire at all after all this. It acted like it was flooded.
Does anyone here have any ideas of what I should try next?

NOTE, while the engine was running we checked the back pressure on the exhaust (handover the pipe) and the pressure was about equal on each pipe, I also had a friend measure exhaust pipe temperature in each exhaust manifold and found the driver side temp to be about 200 degrees hotter than the passenger side..

 

The "could be" list might get lengthy.

Two prime suspects for overfueling are:

1) The CTS (Coolant Temp Sensor) faulty, disconnected, or poor connections.
2) Vacuum hose to ECU broken, leaking, fell off

Cheers
DD

 

Thanks Doug !!!. Now I have a logical direction to start checking things out. Ill let you know what I find in the next couple of evening of real time Jag study. ........Mike

 

As Doug has said,

AND

Read the sticky at the top, No start........... That will give you some more steps.

The cap and rotor warning is 99% the Marelli cars, which yours is NOT.

Remove the condensor looking thing INSIDE the Ign Amp ( the lack box bolted to teh B Bank Inlet manifold). They leak to earth and and a redundant item these days.

Slowly, carefully, and taking yor time is teh ONLY way with these cars/engines. Throwing parts at them is useless.

2 year old fuel, I doubt it woiuld singe your eyebrows, honestly. 3 months down here, and we no got Ethanol.

 

What is the difference between the ECU (trying to find it in my car) and the ECM. I am thinking the ECU is the "brain" electronics box that supposedly is in the rear trunk somewhere. What do I have to remove to get to it so I can check it out?

Also, what is the ECM and where is it or is it just another name for the ECU?

 

They are the same thing. It is sited in the boot, inside the RH buttress. You need to pull out the RHS trim to see it.


Ringed in blue

 

Thanks Greg! It couldn't be more clear than that Pix. Last night I spent some time looking for the coolant temp sensor as well. On my car it isn't where its visible at all, up on the right front side of the engine. Is it covered up?.... maybe.

By the way, I thank you for that FANTASTIC cool write--up you did on the dead engine issue. Mine isn't dead (yet) but understanding what's going on in the fuel system helps me understand more about the car. ......Mike.

 

Aussie speak, so beer is needed,.

Follow the B Bank (LH) radiator hose to where it attaches to the thermostat cover, keep following rearward, CAREFULLY, dont spill the beer, and on the backside of that alloy casting arrangement is the CTS. It will have a rubber boot, maybe, a connector the same as the Injectors, and 2 wires attached.

It may be hidden under all sorts of things your market sadly bolted onto the V12.

This snap of mine shows it in it inside the Green circle, the Brass thing, and NO, I am NOT a computer whizz kid.
Mine has ZERO emissions junk, so your sense of adventure will need to be switched on.

 

Just to clarify Grant's photo

ENGINE temp sensor ringed in RED

AIR temp sensor ringed in BLUE.

The sensors are different, event though they look the same. MARK the wires to them before you take them off the sensors, they must not be mixed up.

 

Thanks Greg,

The joys of one eye.

We all need a Wingman, and I got the best, HA.

Agreed, dont mix those sensor plugs up, it will NEVER start if you do.

 

Any small service I can peform for the Mighty One is a mere drop of repayment in the Ocean of debt we all owe the Mighty XJS Prophet of the Southern Cross.

 

Amen!!

 

Holy smoke! My main problem here turned out to be my car is covered up with too many vacuum hoses. CTS is behind the hoses somewhere so I'll have to remove some of the emission crap to see it. Looks like my work is cut out for me this weekend trying to get this sorted. Thanks for the directions and Pix. What an adventure, ....a fun one. .......................m

 

MAAAAAATE

1) LABEL EVERYTHING YOU TOUCH, your mempry is not as good as you think, and schematics for USA emissions crap DO NOT exist in any clarity.

2) Fill the beer fridge, ya gonna need it.

3) Move to OZ, NO emissions, and you get the real V12, not the poverty pack.

Just enjoy, REALLY, its not that complicated, and our sense of humour must prevail.

 

I got home after work yesterday with lots of enthusiasm to work on the 88 Jag. From that point my enthusiasm went down hill. I decided to check out the potential over fueling issue in the trunk (boot?) but didn't get very far because the spare tire seems to be hooked or jammed in such a way that it won't come out. Things were not looking good here. Knowing that I only had a couple of hours to get anything done I chose to address the tire issue later when I have some help manpower help. I need my new teflon throttle linkage bushings installed (bought 2 years ago). I searched all over and both the bushings are missing, Looks like like I need to order a couple of more teflon bushings. I think I got them from somewhere in "Jolly-Old" but don't remember. So, the CTS is still covered up with hoses on the FL side of the engine. I started thinking I'd attack that issue when I looked at the time I had wasted and gave it up till the weekend. My conclusion was simple, ......I didn't have any BEER before I started the evening. ...........................m

 

As I noted above, I bought 2 of the new teflon throttle bushings for my XJS a couple of years ago and now I can't find them. I seem to remember that I bought them from a fellow in the UK. Now, after a thorough search I have to admit that I have lost them. So, ................Are they still available and if so, where can I order them from. Any help is much appreciated. ...........Mike..

 

This guy sells them. From Lithuania. I've bought several things from him, top quality.
https://www.ebay.com/itm/32449399827...mis&media=COPY

Jon

 

I have gotten stuff from him also, including AAV rebuild- excellent quality!
John

 

Thanks to you all who responded. I just ordered another set, now that I know who had them. I did finally find the paperwork from the first set I ordered before, delivered April 2023, but still, they are lost in a "safe place" my shop somewhere.