My 1992 (5.3 Liters, 12 Cylinders) xjs jaguar was turning off at traffic lights and shaking too much. I had to give it extra gas to not let the car turn off at traffic lights. A jag mechanic told me my car needed a tune up.

I replaced the spark plugs but now the car has no power and turns off when I put it in drive.

I would reallly appreciate any advise on what to do.

Thank you

 

OK, you appear new, so welcome to our side.

The V12 you have in the '92 is commonly referred to as the "Marelli engine", meaning it has Marelli engine management items, mainly the distributor.

The list of possibilties is nearly endless, I KID YOU NOT.

The MAIN items I know of are:

Rotor button shorting, VERY COMMON.

Distributor cap cracks.

Spark plug leads.

Dropping one bank of cylinders, so it runs on 6 cylinders, but eventually the "cat" on the dud side catches fire, as does the car. This is usually rotor related, and/or coil-module issues.

One or both of the coils go flaky.

One or both of the modules that control the coils go bad.

The crank angle sensor, front LH of the timing cover gets hissy, as does its connector just near the oil filler cap. Usually a dead engine with this.

There is a book, "Experience in a book" by Kirby Palm, and it is FREE to download, and is HUGE, and is a MUST READ for any V12/XJ-S owner in my opinion. It discusses at length the Marelli issues, and best of all, how to fix it yourself.

I am not trying to "fob you off" far from it, but the Marelli cars have oddities all their own, and to list all of them here is not my way of sorting it. You will need a basic understanding of the system (the book), some serious (easy) diagnosis, and then asking here as you go.

IT WILL BE FIXED, but it may/will take time and effort.

The few I have had issues with have ALL had the rotor issue, then the cap. the coils is rareish, as are the modules.

 

Welcome to the Forum Alberto, Grant has certainly given you something to think about.
Maybe you would also consider posting an intro in the new members section, you'll find it here New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum

 

Wow- I had no idea that Joseph Lucas had an Italian-born twin. You guys have my admiration for perseverance.

 

HAHAHAHAHAHA.

I call it the "joys of real motoring", and it MUST have 12 cylinders.

Only got 2 V12's now, withdrawal will set in soon me thinks.

 

endless is an understatement.

 

Grant Francis,

Thank you for the information you gave me. I am going to read the book and hopefully I will be able fix my car.

Best regards

Alberto

 

Come on guys! yes, I have had issues with my 12s, but no more than with other cars of comparable age.



The only real difference is that whatever items you change there tends to be more of them. But Francis' list is a good starting point. I would definitely get a new rotor and cap, just remember that the items currently available are mostly of a very poor quality. Give it a set of plug cables too. finally, be real scrouplous about setting the plug gap exactly right. Personally I have found that GKN standard spec plugs work best. Coils go gradually bad as the insulation breaks down with age. Easily seen if peeking at a running engine in the dark as there will be tracking externally in addition to the internal tracking.

 

Hi Francis,

I am not really a mechanic but I will figure out how to fix my 1992 xjs. Thank you for all your input......really helpful.
I broke one of the spark plugs when I was replacing them. I then took my vacuum to suck out the little pieces of glass that went into the engine. I believe that messed up the vacuum. The car showed all the signs of a marelli ignition problem. I cranked it a few times and walked away because the fuel smell was alot.

I left the car in my gagare for a couple of months ( just got busy with life), but when I returned the car fired up perfectly. Drove it and did 70 miles no problem in the highway.

The car still dies in local car trafic. I read in the book you suggested that someone's was dying after 15 minutes.
I brought the car to a jaguar delear for a diagnose and they said the car was perfect, bu it died on me in my home.

I know it has to be the crank sensor and will replace it. Would you please tell me how to find and replace the ( I think two of them) crank sensors in my XJS 1992 5.3 LT xjs?

Best regards.

Alberto

 

The craks sensor look like this:

Wells Crankshaft Position Sensor 18" Wire Lead SU4716, PC452


One at the front of the engine at the crankshaft pulley, one at the rear of the engine at the flywheel, down low, left side as as I recall....not 100% sure about the left side part. my memory isn't what it used to be.

Replacement is easy but routing the wires i a little tricky....not much room to thread them through the nooks and crannies.

Don't drive the car unless you're *sure* the Marelli ignition is firing both banks all the time! Bad things can happen! Really bad. Ruin-your-day bad :-)

Cheers
DD