Hi: I would like to know if someone can shed light on my problem. I have stored the Jaguar in a rather damp garage and I'm trying to get it out however it starts fine and idles fine but when I try to drive it or accelerate it runs extremely rough and the catalytic converter gets red hot.
Any help will be very much appreciated. Regards, John

 

HI: There might be a clogged catalytic converter in play here. If the exhaust gasses are being trapped, heat will build and a blocked cat will definitely effect performance.

 

Is the Check Engine Lamp on? If so, what Fuel Fail code is stored?

A catalytic converter can overheat from a very rich mixture too, such as unburnt fuel in the exhaust. A fuel injector stuck on or leaking, bad fuel pressure regulator, faulty coolant temperature sensor, etc can cause an overly rich mixture or unburnt fuel in the exhaust.

Nick

 

Hi John,

I apologize in advance for the length of this post. Once I got started I couldn't stop.

Your rough running and red hot cat make me suspect that one or more spark plugs are not firing. Storage in a damp garage makes me wonder if condensation may have formed inside the distributor cap, so that would be something easy to check. While you have the cap off, look for traces between the spark plug cable electrodes, wear or erosion on those electrodes or the rotor tip electrode, and any signs of arcing down the distributor shaft. Rust on the distributor shaft is a good indicator that you've had condensation.

If everything looks good under the distributor cap, you could pull each spark plug one at a time, reconnect it to its plug wire and ground the threaded sleeve with a jumper cable, then crank or run the engine briefly to check for spark.

As Nick suggested you should check for stored diagnostic trouble codes. To do so, turn the key to position II (ON) but do not crank the engine. Press and release the VCM button on the trip computer to the right of the steering wheel. Watch the odometer display window below the speedometer for a message. DTCs are displayed in the format of "FF" or "Fuel Fault" and a two-digit number. If you get one code, there may be more. Let us know and we'll help you access the additional codes. You can look up the meaning of the codes on pdf page 113 of the Haynes manual. You can download a mostly-complete U.K. edition here:

Haynes Jaguar XJ40 Repair Manual

Check for mold on the air filter or a rodent nest in the air filter housing.

Another possibility is condensed water in the fuel tank that has settled to the bottom of the tank and is being sucked into the fuel feed pipe by the fuel pump causing poor combustion and raw fuel in the cat. To check for this, you can disconnect the fuel line from the inlet end of the fuel rail (closest to the fire wall / bulkhead), aim the hose into a suitable catch container such as a quart glass jar with a rag wrapped around the fuel line to contain splashes, then turn the key to position II (ON) without cranking the engine to allow the fuel pump priming burst to shoot fuel into the jar. Turn the key off for 10 seconds or so, then back on to repeat the priming burst until you have a cup or more of fuel in the jar. If you can't get much fuel this way, try removing the fuel pump relay and jumping its load contacts (usually terminals 30 and 87) with a large paperclip bent into a U. Place the jar of fuel in a safe place to sit still for 30 minutes or more, then look for a line indicating that water is present and has settled to the bottom of the jar with gasoline floating on top. If you find water, you can use the fuel pump to remove it from the tank by slipping a garden hose or a section of 5/8 inch heater hose over the fuel line you disconnected, aim the other end of the hose into a gas can, then jump the fuel pump relay to pump it out.

If it's been awhile since the engine had a tuneup, that may resolve your issues. A good XJ40 tuneup includes the following:

Spark plugs of the correct type (Champion RC9YC - nothing else) correctly gapped (0.9 mm),
Spark plug wires (the original ones by Rists were of excellent quality but they eventually wear out),
Distributor cap and rotor
Air filter
Fuel filter
Check the drive belts, hoses and fluids and re-tension/replace/top up as necessary
Disconnect and clean all the electrical connectors in the engine bay with zero-residue electronic cleaner spray
Disassemble and clean all the engine bay ground points, including the engine ground strap (which is the ground path for spark)
Remove and clean the crankshaft position sensor (CPS) and its electrical connector
Remove the air intake and crankcase breather hoses and clean out all the oily gunk
Remove the throttle body and clean the inside, then drill drain holes in the plastic housing for the throttle position sensor (TPS) and flush it with electronic cleaner until the fluid emerges clean.
Clean the electrical connector on the oil pressure transducer/switch
Add a bottle of good fuel injector cleaner such as Techron to your next full tank of gasoline/petrol (I do this at every oil change)

A few additional worthwhile things to do to improve reliability are to replace the CPS with a new one and put the old one in the trunk as an emergency spare, replace all of the blue Hella relays in the engine bay and behind the passenger side knee bolster below the glove box with new sealed relays (Bosch makes good replacements), and flush the engine coolant and brake fluid and drain & fill the transmission fluid three times.

Please keep us informed!

Cheers,

Don

 

Hi Retroren: Your help is very much appreciated. Thanks a million!! Regards, John

 

Hi: NTL1991. Thanks a million for your help. I very much appreciate it! Regards, John

 

Hi Don B. Wow please don't apologize for the long message. You are much more helpful than you know and I can't thank you enough! Regards, John