i have a 53 plate mondeo 2 ltr common rail diesel it black smokes constantly mostly when accellerating smoke is heavy any ideas thanks

dave, June 2009

I had the same problem with a 140K Mondeo Common Rail Diesel TDCI. The cause was that the EGR valve was heavily blocked up with soot. Apparently this is a common fault. Remove the EGR (just before the inlet manifold. It has 4 connections: air hose from intercooler (going straight up), a metal pipe from the exhaust (from the nearside of the car), a thin vacuum line (top of the valve) and it bolts on to the inlet manifold - it is at the front of the engine and easily accessible with the engine cover removed. Later models 03 on have an electrical connector to the valve as well). It is easy to remove and clean (but very messy). Car should also drive a lot better whn valve is cleaned.

Dave L, February 2010

Black smoke can be caused when there is an improper air to fuel ratio. The fuel does not burn completely and the partially burned particles are expelled in the exhaust. One of the most common causes of black smoke is an air inlet restriction. This can be anything from a plugged air cleaner, an intake hose collapsing or anything else causing an air flow problem even plugged exhaust. On automotive applications the airflow through a paper filter is sometimes restricted enough to cause black smoke especially on acceleration. K & N has developed an air filter that allows for excellent filtration as well as plenty of air flow. The filter is also recleanable and can be used up to 50,000 miles without having to be cleaned.

Injector malfunction is also a common cause for black smoke as is incorrect engine timing. Overfueling can also cause black smoke and is one of the reasons setting a fuel system above factory specifications is strongly discouraged. Internal injection pump problems can also result in black smoke.

Chicks Fan, June 2009