This LRO reader emailed LRO.firstname.lastname@example.org to ask our experts why his Discovery 2 struggles with low revs.
My Discovery 2’s Td5 engine is proving troublesome. The engine starts okay from hot or cold but holds back a little at lower revs. However, the main problem is when starting a hot engine that has stood for an hour or so – it smokes and misfires for the first couple of hundred feet, smelling of unburnt fuel. If I’ve had a good run – cruising on the motorway, for example – and then leave it for an hour, it doesn’t do it. I had a full reconditioned engine fitted; new fuel pressure regulator, all new filters, new airflow meter, all to no avail.
The Land Rover dealer’s code reader said ‘Low ambient air and coolant temperature out of range’. It smokes and misfires only in the lower rev range: when I accelerate, it clears. Any help would be greatly appreciated.
Kevin Groom, Sawley, Nottinghamshire
The obvious suggestion is to check the injector loom – if this has become contaminated with oil, it can cause misfires and give spurious readings. Just a thought, but I wonder if you’ve been running it on biofuel? Td5s don’t like that.
When you had the engine replaced, were genuine Land Rover injector seals fitted? And have they been checked to make sure they’re not at fault?
When the franchised dealer’s technician read your on-board computer for fault diagnosis, did he mention which readings the coolant sensor showed when it was both cold and hot? And do you have the same information for the airflow meter and MAP sensor? These readings may help to diagnose the fault correctly.
This workshop advice appeared in the August 2015 issue of LRO. Back issues are available to download on digital devices here.