Cold starting issue

[Wag]

Now its sub zero outside, the old 2.0 hdi has a bit of trouble getting going in the morning.
Recent new battery but really slow turnover first thing.
Pre heater light goes out after a couple of seconds and I try to fire it up. It just about gets going but after that initial fire up its fine all day. I'm doing 100 miles a day so it's getting a good charge time.
Any suggestions?
I thought something might be turning on in the car when I'm not there, as I've previously found the radio had switched itself on before now.

[PeterN]

Could be a tired starter motor or a high resistance in the wiring from the battery. Check the voltage actually on the starter when its turning over and then check across the battery as its turning, if there is a large difference check all the connections. Also test the voltage between the battery negative connection and a good earth point, much of a voltage difference would indicate a poor earth connection.

Peter

[Wag]

Thanks for that. The strange thing is, it spins up freely once it's been started for the day. Does that suggest anything else?

[PeterN]

The resistance to it turning is much less when the engine is warm so it doesn't need so much energy to turn it.

Peter

[MarkD]

I have the same issue. If the temperature drops to freezing overnight forget it! Similarly in the summer when it’s hot it’s difficult to start, shudders like mad.
Looking at an earlier post best explanation I’ve seen is that the ecu isn’t getting the correct temperature signal and hence doesn’t open the injectors correctly?
It runs perfectly otherwise, no fault codes, so all a bit of a mastery?
2004, 406 110hdi.

[PeterN]

The only other likely problem is air getting into the fuel line, but that would likely make it difficult to start when hot as well, except that when the engine is turning over fast it can pump the air through the system before it gets into the pump and injectors. I have had this problem with my C5. Have you changed your fuel filter lately?

Peter

[Doggy]

The ecu will not initiate injection until it 'sees' a cranking speed of >60 rpm

Uneven running immediately after starting could indicate a glow plug problem - the glow plugs continue to operate for half a minute or so after starting to help even things out, (roughness is likely caused by not all cylinders firing initially). I accept this doesn't explain hot starting issues.

Excessive injector wear can also prevent starting, might be worth trying a leak off test.

[MarkD]

The only other likely problem is air getting into the fuel line, but that would likely make it difficult to start when hot as well, except that when the engine is turning over fast it can pump the air through the system before it gets into the pump and injectors. I have had this problem with my C5. Have you changed your fuel filter lately?

Peter

That’s very plausible. I have changed the fuel filter, it made no difference, although the pipe in did come off, so maybe there’s a weak point in the system?

[MarkD]

The ecu will not initiate injection until it 'sees' a cranking speed of >60 rpm

Uneven running immediately after starting could indicate a glow plug problem - the glow plugs continue to operate for half a minute or so after starting to help even things out, (roughness is likely caused by not all cylinders firing initially). I accept this doesn't explain hot starting issues.

Excessive injector wear can also prevent starting, might be worth trying a leak off test.

Tried a new crank sensor (located beneath the thermostat cover) thinking that could be the issue, and a new battery as well..........it just laughed at me

[MarkD]

Success! EGR valve stuck open. Now blanked off, new starter motor fitted, good as gold.

[Doggy]

Well done.

If only I could do that with the cursed Citroen and avoid stall roulette at every junction.