Diesel starting problems

The car is a Focus 2.0 TDCi with 153k miles. The engine takes a couple of attempts to start cold and hot. I can drive for 50 miles, stop to fill with diesel and the engine won't start first time.

If I give it 1/4 throttle as I start, it will usually start first time. The glow plugs have been fitted for about 120k miles so are probably past their best but given the problem happens when the engine is fully warm, I don't believe its the main problem.

I'm trying to figure out what the 1/4 throttle is doing to help.... is it giving extra fueling or is opening the throttle valve helping in some way. Once started, the engine performs just as good as it did when new.

Reply to
Paul Giverin
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I assume it is spinning at a normal good speed meaning that the battery is good?

First thoughts would be an air leak at the fuel filter or a pin hole in a fuel pipe. I cannot remember if those actually have a throttle flap or swirl valves, but if so it might be gunged up, restricting the inlet on a diesel will reduce the compression pressure, which would not then get hot enough to light the fuel, so that might be worth looking for and at.

Reply to
Mrcheerful

Thanks MrC. Engine spins well... I think the battery is good. It does have a throttle flap.

I know this because when the car had done 30k miles, I had a starting problem fixed under warranty where the car would start but not respond to throttle at all and black smoke from exhaust. After Ford had replaced the injectors, they found throttle flap was sticking closed. Engine was getting just enough air through the EGR valve to achieve tickover. So I know that it will start with throttle valve stuck closed.

Reply to
Paul Giverin

so if the egr valve is coked it might not have enough air to get going, hence giving it a bit on the throttle gets it going, after that the electronics take over and it keeps going, maybe. an inspection of the egr and the throttle flap sounds like the right things to start with.

Reply to
MrCheerful

That's certainly something to think about although I did replace the EGR valve about 4 years ago and when it failed, it threw up a check light and fault code. Mind you, on that occasion it failed electrically rather than getting clogged up. If its clogged up, wouldn't it still,throw up a code?

Reply to
Paul Giverin

Only if the egr has a flow detector built in.

Reply to
MrCheerful

Not nessie-celery. The Bosch/BMW system calculates the expected air mass the cylinders should be consuming (based on revs & air pressure of manifold) and subtracts an expected EGR air mass amount (from a table based on how much EGR demand the ECU's calling for) and compares it to the value from the MAF. If there's too much variation it knows the EGR has been blocked/disconnected/removed and throws an EML and fault code.

Reply to
Scott M

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