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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21990
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a jaguar xkr 4.0 1998 it starts fine but as the engine

Resolved Question:

i have a jaguar xkr 4.0 1998 it starts fine but as the engine starts to warm after a couple of minutes it goes nuts ,misfiring runing very rough ,if you accelerate it will go but im getting faults displaying in instrument binacle at random it is not going into limp mode but does light up .i have an icarsoft i930 diagnostic tool but it is showing no error codes.
Submitted: 1 year ago.
Category: Car
Expert:  Matt replied 1 year ago.
Hello this could be incorrect fuelling due to a faulty water temp sensor. If this is the problem then the ECU will be leaving the car constantly ' on choke' and not reducing the fuelling as the engine warms - so unplug the sensor and clean the contacts on both sides with some switch / electrical cleaner (not WD40) and inspect the wiring for any signs of damage to the insulation especially where it runs over other components and through the bulkhead- if this doesn't help consider replacing the sensor as they're not expensiveCheck for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate. this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers
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Customer: replied 1 year ago.
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Customer: replied 1 year ago.
i have already fitted a new temp sender and exhaust and cats were all replaced last year when the car was running fine only thing i have noticed is each time i try the car it is slowly taking less time for it to malfunction the last time when i accelerated hard it set it off and the traction control light came on this reset when i stopped and restarted the engine.