I took my 1994 XJ12 out this evening to pick up takeout, 4 miles from my house. On the way I notice a burning smell and some loss of power/acceleration, and the check engine light comes on right when I get where I am going. At parking I notice smoke coming from the hood so I turn off the car and take a look. The catalytic converter on the right side was the source of the smoke, it was glowing red, to the point I thought I had a fire. I also noticed that I had a large leak from my power steering fluid reservoir and some of the fluid had leaked down on the exhaust. I am not sure if that could have caused the burning or not.

Meanwhile, I don’t smell any gas and I am not far from home so I try to make it back. That was a mistake. The car loses power the whole way, I can’t get over 30 mph. I can’t accelerate, interior lights are dimming, and the car is making all sorts of noises, including what sounds like flapping from that right side. Eventually I pull off and I lose all power steering, then the car dies. Now it won’t start. I just got towed home.

My question here is what could have caused this and specifically why won’t it start now? I get why a cat may overheat, but I don’t get the connection to the power steering reservoir problem and I don’t get why it won’t start unless there is some sort of safety feature? Not a great time...

 

I have 3 dead X308 sedans in my back lot that have 'melted' engines from loss of coolant but continued to drive because the driver was 'ALMOST THERE'.
Cars towed to me for diagnosis, engine failure, no compression.
The customers never came back to pick them up 5 or more years ago so I use them for parts cars.

Your ignition system has partly failed.
I suggest you cool it down and see if it will crank?
Might just need new cataverters but..........................

 

Thanks. Thankfully the engine never overheated. It cranks now with no problem, still sounds weird, which I assume is from the cat being junk. I'll take it to the mechanic to try to source the underlying cause.

 

From what I've read, (I have a 6-cylinder) the distributor on the 12 contains 2 rotors, one for each bank of 6 cylinders. When one ignition bank fails, the car still runs on the other six with fuel continuing to be delivered to the "dead" side. Unburnt fuel builds up in the exhaust and eventually ignites. Not pretty!!

Larry

 

'94's had Marelli ignition.
Google Marelli failures...there's lots of info.
Rob

 

CHS
It definitely sounds like you had an A or B bank meltdown, which is very serious and probably one of the biggest reasons for XJS car fires. At this point I would direct you, post haste, to Kirby Palm’s Help guide and take note of the warning on page 161:
”MARELLI-CAUSED DISASTERS: The combination of Marelli ignition and catalytic convertors can, and often will, result in the destruction of the catalytic convertors and possibly the whole car. This is not a section of this book to be glossed over lightly! If you have a car with Marelli ignition and catalytic convertors, you need to take a proactive role in making sure your car doesn’t become a burned-out hulk in a junkyard somewhere”

I have a 1990 XJ-S, 5.3 v12. On a short fall ride through a nice neighborhood with my wife and dog my wife said she smelled smoke (top down). I said it was probably someone burning leaves. I rounded the corner and stoped at the stop sign. When I started up I had no power, pumping the gas did no good and then I smelled the smoke also. I immediately pulled into someone’s front yard. Having read Paul’s guide prior to buying my car, fortunately, I recognized the symptoms of what was an A Bank failure, jumped out of the car and grabbed the fire extinguisher behind the seat (again thanks to Kirby Palm). I looked at my wife who had that look that all of us men know well - “I told you so”, to which I said “grab the dog and get the hell out of the car before it burns up!” Fortunately it didn’t, I caught it in time and had it toad to my mechanic. The cat was red hot and completely melted the trans vacuum actuator that is near it.

After an autopsy we found a burned and arced rotor. I ordered a new rotor and followed the suggestion in Kirby Palm’s guide, page 162 “What to do” and have lived to tell this story.

 

Thanks Greg. The sad part is that I have also read the Kirby book and knew about this issue from my restoration of my XJS, it just never occurred to me at the time for some reason. That’s my own stupidity.

I honestly think the weather saved me here, it was no more than 25 degrees out when this happened and so even though I pushed it and the cat got crazy hot it never developed a real fire. I’ve ordered a new cap and rotor and will install those and then see if the cat can be salvaged. I’m lucky not to lose the whole car, but hopefully its a fairly simple fix at this point.

 

Glad it all worked out ok. Chalk it up to lessons well learned and valuable advice to future readers.
One last thought, not knowing the XJ12 and what trans you have (I assume the same as the XJS), if it has the trans vacuum actuator on the side where the burnt cat is then the heat of the cat will have surely melted the rubber vacuum hose and probably damaged the actuator.

Greg L
Eastern PA, US

1990 XJS 5.3L Convertible
1964 E-Type S1 FHC - sold and greatly missed.