Engine problem with Jaguar X type petrol V6

[notax]

A friend of mine has asked me the following, any ideas appreciated:

'the engine cuts out when travelling at,say,4000rpm for a
period. It shows up as lean fuel mix indicating a possible air leak/vacuum
problem or sensors.

Garage/s have changed loads of stuff but without finding the real reason. Any thoughts would be welcomed.'

[Pumaracing]

So it's running out of fuel. Most obvious would be a blocked fuel filter and if that's ok then an intermittently failing fuel pump.

[stevieturbo]

Pumaracing said:

So it's running out of fuel. Most obvious would be a blocked fuel filter and if that's ok then an intermittently failing fuel pump.

Often with modern stuff faults arent as simple as that ( but always worth checking )

Best suggestion is to have someone diagnose it properly, as there is nowhere near enough information yet.

You need proper engine sensor data when the engine is running ok, and as this fault appears to see if there are any anomalies that might be causing it.

Blindly reading basic fault codes is not enough.

[Steve_D]

Does it do this fairly frequently and repeatably?
If it is local it may be worth putting it on our rollers then we can stand there and test things when it happens.

Steve

[GavinPearson]

Change the fuel filter, reset the codes and then see what happens. The likelihood is it will be fixed just by doing this.

[notax]

Thanks for the replies, which I will pass on. Friend is based in Romsey, so not too far from you Steve. I will check the frequency of the problem and report back when he returns from holiday

[Pumaracing]

stevieturbo said:

Pumaracing said:

So it's running out of fuel. Most obvious would be a blocked fuel filter and if that's ok then an intermittently failing fuel pump.

Often with modern stuff faults arent as simple as that ( but always worth checking )

And often they are.

stevieturbo said:

Best suggestion is to have someone diagnose it properly, as there is nowhere near enough information yet.

You can't electronically diagnose a blocked fuel filter as nothing will show up.

The clues as always are in the symptoms. High rpm and therefore high fuel demand for extended periods. Classic fuel starvation symptoms but the engine will still run fine at lower rpm/throttle position.

If so it should be reproducible on demand. Just boot it hard and it should cut out. Leave it for a while and it will restart again.

[stevieturbo]

Pumaracing said:

You can't electronically diagnose a blocked fuel filter as nothing will show up.

The clues as always are in the symptoms. High rpm and therefore high fuel demand for extended periods. Classic fuel starvation symptoms but the engine will still run fine at lower rpm/throttle position.

If so it should be reproducible on demand. Just boot it hard and it should cut out. Leave it for a while and it will restart again.

Actually you can.

If fuel pressure is monitored that is one clue. As is the ecu trying to compensate for a lean mixture reading by opening the injectors longer. Both of which will be very apparent on any decent scan tool.

Or if in open loop, mixtures going lean for any given IJPW for no apparent reason would be a sure sign of lack of fuel flow.

[Pumaracing]

Ummm, no you can't. You can diagnose lack of fuel but you can't diagnose a blocked fuel filter. No diagnostic test could narrow things down any further than to the various fuel related options such as blocked filter, blocked fuel line, faulty fuel pump etc.