My Jaguar sometimes stalls on idle. It usually happens when the car has reached the usual warm temperature (about 5 minutes after I turn it on). When I reach a light and stop, the RPM will dip for a few seconds and recuperate, but at other times it won't causing the stalling. There is no code. I've replaced the fuel filter, spark plugs, air filter. One particular and strange detail: when I pour a "system fuel cleaner" the problem stops until I have to refuel the car when it reaches empty. It's annoying and driving me crazy. Thanks for all your help!

 

Before doing anything else clean the throttle body. Post back if details needed.

Cheers
DD

 

What is the make and model of your spark plugs?

 

I'm almost positive I used the Bosch Iridium spark plugs. Also, I cleaned the throtle (didn't remove the whole assembly, just removed the rubber it and cleaned it), but so far same symptoms. Again, if I add a system fuel cleaner, the car performs great. Also, the problem seems less noticeable when I use Premium gas.

 

The X300 can be highly sensitive to spark plug resistance. Champion RC9YCC or RC12YCC are the safest choice, and the standard plugs recommended/installed by Jaguar. Before you do anything else, I would try those plugs.

We had stalling on idle in one of our X300s, and spent no end of time and money trying to fix it. In the end, it was just the (NKG?) plugs - they were brand new, but the Jag didn't like them.

 

YEP,

Mine did that and the NGK were not old, tried Bosch, worse, back to NGK, all OK.

Changed the CTS (coolant temp sensor) and that improved it considerably.

Our 98 octane fuel is the best for this car (all I run), and the regular cleaning of the throttle body and disc is mandatory. That I learnt from all the V12's over toooooo many years.

 

A bit odd, but if that's the case I think I have the fuel injectors professionally cleaned and see if it helps









Also odd. Octane rating is way at the bottom of my list for a rough idle problem....although low *quality* fuel might be a candidate.


Cheers
DD

 

NGK only for that car. And premium gas also.

 

Hi. I had exactly the same symptom the other day. Mine was caused by the crank position sensor. I heard from a mechanic that in many cases the stall while hot is caused by the fault crank position sensor. When it is dying there will be no code, unless it has completely gone.

About the connection between the fuel cleaner and the stall, sorry I have no idea. It could be a coincidence.
If you have done more than 100000km it is worth exchanging it.

Hope this helps

 

 

The genuine plug is Champion's, as Oubadah mentioned.

I also heard that iridium plugs are not good for our cars.
They could give damage to the ignition coils. At least you should use platinum plugs. In Japan some dealers install platinum ones on X300s.

 

I cleaned the throttle body again. I also cleaned a sensor on top of the throttle (TPS?) and the car seems to be working better. No fault yet, but it's only been one day. Also, the last time it stalled the check engine light came up and gave me this code: P0727. I looked for it and this is what the explanation is (in quotation): "Fault Description: Engine speed, no signal. Possible Causes: Engine stalled at a road speed above
10 mph (16 km/h)
ECM to TCM engine speed signal circuit open
circuit or short circuit to ground
ECM engine speed signal error (TCM failure)"

Any ideas?

Thank you for all your help guys...and I will replace the iridium plugs with Champion's.

 

EGR valve sticking??

 

Is your car X300 4.0, isn't it?

TCM means Transmission Control Module, so you could lift up your car and check your AT module. I have heard there are several cases that XJR's GM transmission module or its harness goes bad... I don't know about the ZF of 4.0, though.

If "engine speed, no signal" means the engine speed signal from crank position sensor, you will have to replace it.

 

The problem persist. I'll replace the spark plugs today and report back, but it seems that the crank position sensor may be the culprit, from your observations and the code.

 

Gentlemen, I'm happy to report that the problem is solved. I replaced the Bosch Iridium sparks plugs with Champion spark plugs and that did the trick. It's amazing how such a simple detail could cause a stalling problem on the XJ6. So, if you have a similar problem (a intermittent stalling on idle) be sure to have the correct spark plugs before any expensive repair. Thank you for all your good advice!

 

Good news :-)

Question: in addition to the stalling issue did you also have a rough idle? If so, did the Champion spark plugs change the idle quality?

Cheers
DD

 

When I’m driving the car the engine just stops running, when I try to start the engine it just turns won’t start. I park the car wait about 30 to 45 minutes and the car starts. It happens about once every two months and it seems like it happens when the weather gets warm. Do you think it could be the throttle body or the fuel pump or the fuel pump sensor? I don’t think it could be the fuel pump because when the car is running it will cruise at 90 with no problems in power.

 

I think it's about time this tip found it's way to the FAQ sticky

I had it, then it popped up again HERE, and now Enlacalle too. All fixed stalling with the Champion plugs.

 

Responding Doug: No, the car did not have a rough idle, so it feels the same, except that changing the plugs fixed the stalling problem. I wonder why when I poured fuel cleaner the car didn't stall. My hypothesis is that, because the cleaner increased the octane, the engine did not require a "good" spark from the Iridium plugs that were not performing right due to the "plug resistance" mentioned by Oubadah. Of course, anybody can have an opinion...