Rough on start-up
Q On very cold mornings, when starting my 2014 Ford Mondeo
2.0 diesel (engine code TXBA) with 126,000 miles, it seems to tick over on three-cylinders for 90 seconds before clearing, and then runs okay. The dash light for the glow plugs no longer illuminates – is this relevant? Starting at all other times is fine and the Mondeo runs well except for an occasional surging, as if the choke is on a bit. I have checked the engine fault codes with my Foxwell NT200, but none are showing.
J E Easton
A The fact that the glow plug light does not illuminate may be significant and could indicate that the plugs are not operating. The engine could still start without the aid of the glow plugs, but there will be an initial running problem as the cylinders get up to temperature.
As your glow plug light does not operate, the first point to confirm is the feed to the plugs. After removing the top engine cover, you should check that the glow plug terminals are being fed at battery voltage when the ignition is first turned on. If they are not, the glow plug module may have failed. This is positioned near the coolant header tank on the offside inner wing.
If the glow plugs are being fed, I would inspect them to ensure that one or more of the plugs have not failed. This can be done without removing them by using an ohmmeter. After disconnecting the feed wire from the glow plugs, the probes from the ohmmeter can be placed on the feed terminal of the glow plug and a suitable earth; the reading should be around 2 ohms. A faulty glow plug will be shown up by a reading which differs greatly from this.
If no problems are found with the glow plugs, the next check would be the leak-off pipes. These involve a plastic union with a small O-ring and are held in place by a spring clip. The O-rings tend to perish after a while, allowing air into the system overnight – a minor diesel leak in this area will be a sign of this. This will give the symptoms you have and will not generally leave a fault code.
If these checks come to nothing, you may have a partially blocked injector. Autodata recommends adding one litre of cleaning additive to a quarter-tank of fuel, after ensuring that the fuel tank is at least a quarter full. Mix the additive thoroughly with fuel and allow the engine to idle for at least one hour.