Why is my Ford Mondeo TDCI producing blue smoke?

I have a 2.0-litre 2002 Ford Mondeo TDCI 130BHP and had a message saying 'P2339 Cylinder #4 above knock threshold' on the ECU diagnostics check. The car starts fine, but is giving off a lot of blue smoke (unspent diesel, I think). I have been told by a mechanic friend that one of my injectors could be faulty, however I am reluctant to replace them due to the cost. Having read a couple of forums some people have suggested re-programming the injectors in firing order, changing the knock sensor and checking the connection on the injectors. Do you have any advice?

Asked on 30 July 2010 by battle84555

Answered by Alan Ross

Experienced diesel men will tell you the answer lies in the smoke. In your case you are saying it's blue. If that's the case then blue smoke indicates worn cylinder or piston rings, faulty valves or valve stem seals, an engine over-full with engine oil or a faulty injector pump/lift pump, allowing engine oil to be mixed with the diesel.

Faulty injectors would normally be indicated by black smoke. Could you not check with Ford dealership what the code means?

Tags: technical issues diagnostics smoking

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