Good morning.
I need some assistance badly.
I have a 1996 jaguar XJR that I gave not use for 2 years. When I tried to get it started, it was misfiring and started to misfire then backfire to the point that it finally died and won't start.
my mechanic drain the gasoline, change the oil, plugs, gas filter, fuel injectors and filled up the tank with 91 octane gas.
it started but sluggish and huffing and puffing on idling.
But when I drove it on the highway at a speed of 120 km per hour, it was find. Although there was a bit of hesitation at times.
I decided to then buy a fuel injector cleaner.
That's when the problem started again.
Started to misfire badly, while idling, backfiring and the engine died.
Had it towed to my mechanic to my mechanic. He was able to start the engine.
after running it for around 3 minutes, still misfiring and he noticed that the exhaust system was red hot.
Turn off the ignition . And didn't try to start the engine again.

Love my car. Never drove it in the winter for 15 years. Would love and dying to get it going again.
please help.
Eddiec

 

My limited knowledge with these, as both my X300's never missed a beat.

Elsewhere on here, XJS Tech Section, a 6 cylinder member has similar issues, and the opinion is the Cats are blocked.
NOT common, but lack of use, stale fuel running attempts etc all damage these things.

Being an "R", an unrestricted exhaust would be greatly needed in my opinion.

 

That behaviour does sound suspiciously similar to what is happening to my AJ6...and that it got progressively worse. Maybe keep an eye on this thread that Grant referred to: https://www.jaguarforums.com/forum/x...nt-rev-246413/

 

With A ELM - 327 device you can see if it's running too rich for what ever reason

This would be Short Term Fuel Trim ( or mixture ) which has a target value of 0.0 through all ranges of throttle / load

Some causes for the fuel trim to be rich would be cracked exhaust manifolds , manifold gasket leaks including the round donut gasket coming loose with the stud bolts migrating loose , and vacuum line leaks and even the brake booster cylinder with it's manifold attach fitting

One quick vacuum line leak test is the short one at the top of the fuel pressure regulator to the manifold

If you can detect fuel in this vacuum line it would indicate the FPR has failed

 

The 2 wire engine coolant temp sensor on the top front feeds the engine ECU for full engine regulation including using the O2 sensors

Until the coolant temp reaches a certain point the engine will run in a open loop mode which will be rich by design , in the close loop mode the mixture ( short term fuel trim ) will be leaned out

You can calibrate this sensor with the graph on page 78 with a cold engine and a hot engine to see your sensor values swing

9 volt battery powered meter recommended

A dirty connector will mimic a cold coolant reading keeping the ECU in open loop

Have you inspected the ECU connectors for corrosion ?

http://www.jagrepair.com/images/Trai...20-%202000.pdf

The single wire temp sensor next to it is the instrument cluster which is not very smooth operating in scaling up to operating temp

The engine coolant thermostat can fail in the open position and the coolant can fail to reach operating temperature and stay in open loop

Care must be taken as some have broken the thermostat housing casting so more input needed on the correct size of thermostat as there are differences and in the X300 case there is no o - ring in installation where some have found out the hard way

 

I had the same problemand oneof the catalytic converters was stopped upand needed replaced/