My Discovery 2 Td5 recently developed a misfire. I had a local garage check the engine using diagnostics and it detected a problem on the injector harness. I replaced the injector harness, which was an easy enough job and, as the garage recommended, I replaced the engine harness. I also checked the engine ECU for oil and cleaned the terminals.
This has cured the misfire, but I’m now getting an occasional loss of power, accompanied by white smoke. I haven’t done any other work. What do you think is wrong? Barry Petters, Essex
Is this an EU3-emission engine? An EU3 unit can be identified by its exhaust gas recirculation (EGR) cooler across the front of the engine. If so, check the connections of the engine wiring loom to the EGR system.
The EU3 system has two solenoids, one working an inlet throttle valve and the other the EGR valve itself. The throttle valve closes just before the EGR valve operates, causing a depression in the inlet manifold – which causes more exhaust gas to be drawn through for combustion. If these are connected the wrong way around when fitting the engine harness, the valves will work out of sequence, giving the symptoms you describe.