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Matt, Mechanical Engineer
Category: Jaguar
Satisfied Customers: 22893
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 02 x type jag 2.0 petrol. It gets to 75-80 mph

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Hi I have a 02 x type jag 2.0 petrol. It gets to 75-80 mph then the cruise not available light comes on it misfires then shudders. Take you foot off the throttle coast down to 70mph then it normally clears, but it's getting worse. It's been in 2 garages . 1st guy put it on his machine and said its the lamber sensors he changed all of them and the spark plugs. Was a bit better for a wk or two then went back to the same problem. Took it to another garage who said it was the knock sensor this was replaced but still no better. I had it plugged in again, this time I was told it was missing on no 2 cylinder and it was the coil pack ????? What do you think.

seems like quite a lot of parts have been replaced already

can you tell me what fault codes have been pulled off the car?
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Customer: replied 2 years ago.
Hi codes are
Po171 system lean bank 1
Io174 2
Po302 cylinder 2 misfire

OK I'd 1st check the fuel pressure is correct with a running engine

as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Check 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