Hello, I own a 1996 xj6 that I love. I drove it to a friends house last night during a pretty bad rain storm, once the rain died down we went to go get some food when I tried to start my car. It turned over but it misfired and lost power. I was hoping that it would just be the rain and I came out to start it this morning and it’s doing the same thing. It sounds like only 3 cylinders are firing. It idles for about 10 seconds in park before it loses power but it seems to last longer when I put it in neutral or drive. It sounds different from last night, and it doesn’t seem to have as much trouble starting as it did last night. When the engine is running there are no warning lights which is unusual for a jaguar to begin with, but even more unusual since the engine is misfiring. I don’t know what is wrong with it and I am desperate for a fix, if anyone has any ideas it would be greatly appreciated and thank you for taking time to read this thread.

 

It could be water getting into the ECU which is behind the kick panel in the footwell; on a right hand drive car it is on the right hand side of the drivers footwell behind the trim piece.
Not sure on a leftie.

 

Possible failure of the Crankshaft Position Sensor at the front of the engine. It reads the toothed wheel on the pulley. Known to fail suddenly and on all XJ6 of this age. Replacement is necessary because if it hasn't failed yet, it will. Symptom is very rough running and stalling.

The ECU is still on the right side on a lefty car. Its connectors face upward so water might travel down the wires from above.

Also, consider if you fueled up recently. Bad fuel (contaminated with water) will have that effect too.

 

Water in your fuel? The water sinks in petrol so goes straight to the bottom of the tank and hence is quite quickly ingested. Symptoms like you describe, but should pass through without damage unless there is a bucketful in there!

 

When was the last time you swapped out the coils and replaced the plugs?

 

I cant remember if the spark plugs have ever been replaced, I’ve owned the car for 2 years and I don’t believe I’ve ever replaced them, but prior to myself owning the car it was owned by a mechanic, it went unused for over 10 years, and I know they replaced the battery, but perhaps they replaced the spark plugs as well.

 

I suspect the coils are going bad. Grab a 10mm socket and pull all six out. Are any of the boots wet? Do the rubber boots look like they're in bad shape?

Without answering, go on Amazon and buy a set of QYL branded coils for less than $100. Then buy yourself a set of six Champion 71, or RCC12YC spark plugs, checking the gap for .035". (NGK BKR5E also work)

See if that doesn't fix what ails ya.

 

I believe the spark plugs are Champion RC12YC not RCC12YC

 

yes, you are correct!

 

The clue is the bad rain storm you drove through before the problems emerged........

 

I was hoping that it would be a cheap fix but I had to tow it to my mechanic and the bill is $426, not sure exactly what was wrong with it but will update tomorrow when I pick it up. Hopefully if someone else has the same problem they can find this thread, maybe it will help them. Thank you all for giving me suggestions I really to appreciate it!

 

Sorry to hear about your issues - I would’ve done like everyone else is saying and pulled the plugs first, and see if that solved it - maybe coils too (given that it’s preventative maintenance, it’s not a bad thing to do anyway).

Look forward to hearing what your mechanic found. Hope that this is the end of your issues.

 

I have my car back, turns out the crank shaft position sensor went bad, and me trying to start the car made the spark plugs break too. Thanks for anyone still following the thread, and thanks again to everyone who responded, hopefully someone can find this thread if they need it!

 

 

I’m very glad it worked out for you - no one likes repairs, but at times they have to be done.

 

just out of interest, could you open your fuel filler flap and check the drain is clear?

 

That was one of the first things I checked, the next morning it was clear

 

Here is a proposed check list for rough running and misfire, in priority order
1. Crankshaft Position Sensor (cheap, easy and quick fix)
2. Spark plugs (cheap and easy fix, replace regardless if long overdue, Champion plugs are dead cheap - known as "lawn mower plugs"
3. Water in fuel (go to the gas station and find a product that kills water in fuel) - drain dirty/bad fuel if you know how to fiddle with the fuel pump
4. Dirty fuel filter (replace)
5. Fuel Pressure regulator failure (replace)
6. Coils - check that no one looks wet and weird (replace any suspect with a good used second hand a quick solution; replacing all has no harm - long stories about what and where to get new ones)
7. ECU - corroded contact due to water ingress from above (hope this is not your problem, if it is stop leak first and replace the connectors - search this site for details - lots of writing from me about it)

Edits welcomed.

 

Fixed

 

9999. 2. Spark Plugs. They don't last for 50,000 miles like on newer cars. Perhaps not the primary cause of misfires (unless they are already fouled), old plugs are the cause of one of the most common random stalling issues in the AJ16 . It usually shows up as occasional stumbling and stalling while coming to a stop as the revs are coming down to idle. Being they are so inexpensive and easy to replace, it is worthwhile to do it and rule out a possible cause of trouble. It will cure stalling in many cases. If they are over 20k miles (or unknown), replace them.

I suppose the list can look a little different according to a person's experience and knowledge base. But in mine, spark plugs are very important in the AJ16.