I have a 1.8TDCi Focus that has started to run rough. Basically this points to a dodgy instrument cluster or ECU. Car starts up fine first time, but then after driving for a few minutes starts to run really rough. Also temp gauge drops when accellerating, but have had thermostat changed and new temp sender fitted. What does anyone else think this could be? Is it worth fixing or should I just trade it in? Bit gutted, only had it a year and its been a bit of a nightmare.

https://www.youtube.com/embed/0Q71pz7Cv20

What colour is the oil and what condition is the coolant in.

Is there anything on the oil filler cap (underneath)

Jamie

Oil is the same as I have had on any car, black. I did have it changed along with oil filter recently which made no difference. Coolant was changed along with timing belt kit about 5 months ago. No yellow mayonnaise stuff on fuel cap either.

What does it sound like to you?

Does it start ok,

Can you check the battery voltage when the car is off and running

Jamie

Starts first time every time, car runs fine as well. Then after a few minutes it begins rattling and temp gauge falls on acceleration, though after some reading looks like a defective instrument cluster. The car does need a service which will be done when I get paid.

Engine Rattle will not be caused by dials and guages

Cutting out and the car ignoring your key would be the cluster as its a common fault on the 2 and 2.5 (mk)

Jamie

As above the cluster has nothing to do with an engine rattle with a diesel take you're pick from oil pumps to diesel pump diesel filter or the oils ok and thin and needs renewed

Could it be a defective ECU then?

This thread highlights the problems I am having to a tee.

http://www.honestjohn.co.uk/forum/post/?t=59922

Rattling could be :- Little ends/Oil Pump/cam bearings

does the oil light stay on a few secs when you turn the key (engine cold)

ECU will not cause a rattle

Jamie

Getting full service and thermostat changed tomorrow. No oil light on after start up and dont think its a problem with either oil pump or fuel pumps. Will update tomorrow when I get the car back.

Full service done and rattle has gone thankfully! Temp gauge still dropping on acceleration even though new thermostat fitted, so my guess it is being caused by an electrical problem.