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black smoke, mis fire and lack of revs in neutral


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I have a 2.0 d 2007 sovereign, on acceleration i get a cloud of black smoke , is this normal, also when just cruising, say at 50 in 5th gear the car seems to be misfiring. i have no loss of power and it never happens at high revs, a further problem i am experiencing is sometimes (a lot) when in neutral the revs will not exceed 3000rpm, is this normal/?. please help, yours, concerned

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None of that is normal. Given your description I'd say you have a failing injector. They are a common fault on the 2.0D

The black smoke is a result of excess or poorly atomised diesel being injected into the cylinders. Because it doesn't burn properly you then need to put your foot on the accelerator harder to get the acceleration which puts more fuel in which doesn't burn properly etc etc and the result is clouds of black smoke.

An injector can fail to close properly too. When required, the ecu tells the injector to open and close which fires the required dose of diesel into the chamber. A failing solenoid within the injector can mean it doesn't close fully, or if it does it may be slow to react and allow too much fuel to pass before it manages to close, and fuel is continually 'leaked'. This results in excess diesel (also at the wrong time) and causes a drop in pressure in the common rail. It isn't enough to put the ecu light on but it is enough for the ecu to compensate for it by raising the fuel pressure in the whole system. This means all the other working injectors deliver fuel at a higher pressure which in reality is excess fuel. Hence the black smoke.

I'd lean towards one, or more, faulty injectors. The only way to find the failing one is to remove them and pressure test them, although I expect the faulty one will be as black as the ace of spades!

It would certainly account for the smoke, the misfire, and the inability to rev.

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Testing isn't. You only really pay for labour. The test process itself isn't much. However the injectors are anywhere from 95-150 each!

I wouldn't use Jaguar main dealers either. A good local diesel specialist is your best option if you aren't doing it yourself. It's what these guys live for and they are generally very good at it. Expect around £35 an hour in labour and the job of removal and replacing with all new injectors would be around 2-3 hours work.

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  • 3 weeks later...

Did yours struggle to rev up in neutral? I'd agree that the intercooler hose could be suspect but I'd not expect it to cause a revving problem in neutral as the air requirement is far less than when under load. The turbo won't be spinning much with the engine not under load. I'd also expect a lack of power if the intercooler has a leak, but in this case there is no loss of power, at least not noticeable to any great degree

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