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Jagmaster, Jaguar Technician
Category: Jaguar
Satisfied Customers: 494
Experience:  10 year Jaguar master technician land rover master and Aston martin certified
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1994 Jaguar XJS: liter engine..I drove it home..limp mode..converter

Customer Question

I have a 1994 Jaguar XJS v12 with a 6 liter engine. To start from the begining, the ingnition control modual, for the right bank failed and I drove it home under limp mode. I replaced the control modual and later the catylatic converter burned out on the right bank. It set off an check engine code, I do not remember which one. I took it real easy, and drove it home. I found out about the converter after getting it home and working on it later. I could not find a right side intermediate pipe in the United states, so I had gutted all of the catylatic converters, on both sides. Now I get an engine fault code of FF44, which referes to the O2 sensor on the right bank. The car has been taken to the dealer twice, and I have replaced the O2 sensors on both banks. The dealer tells me that the right bank runs a little lien and causes the code and it forses the computer to go into a closed loop. Another mechanic told me that it is caused by a vacuum leak or bad ground. I redid both any ideas?
Submitted: 8 years ago.
Category: Jaguar
Expert:  Jagmaster replied 8 years ago.
Any chance that the exhaust has a leak? If there is an exhaust leak at the manifold or upstream of the o2 sensor, it will try and enrichen that bank. You can back probe the sensor to see if it's operating properly. The computer should be in closed loop. It sounds like they just didn't know what was up. It would be nice if you could find a shop with a gas analyzer, so that you can find out exactly what the car is doing.
Customer: replied 8 years ago.
No there is not an exhaust leak. The round gaskets between the manifold and the down pipe have been changed, on both sides and with new nuts on the studs.
Expert:  Jagmaster replied 8 years ago.
It really seems to me than that you need to find a local shop with a gas analyzer. I think it will save a lot of time, and money to see exactly the engine is doing. It doesn't need to be a Jaguar shop. In fact you will probably have better luck at a shop the tunes hot rods, or customs. I am sure that with those results the actual fault will become more apparent. It's so hard to speculate.
Customer: replied 8 years ago.
Since I gutted the catalytic converters do I need to replace the ECM with one that is for a car that did not have these?
Expert:  Jagmaster replied 8 years ago.
To tell you the truth, it's against federal law to remove any emissions control device. Even in areas where you don't have state emissions. So I can't ethically comment on that too much. I can tell you that the engine should run better with the backpressure caused from the catalytic converter. I don't think the ecm should matter. It should be said that the oxygen sensors will do strange things with the cats. It might be worth trying a non-cat ecm, but I would get the exhaust analyzed first.