Cycling of the glow plug to start car when cold

Car in question is: 2010 Verso 2.0 Diesel 

For the last few years, the car seems to struggle to start if I only start the car with 1 cycling of the glow plug, in the morning. After that it will be fine. Replaced the glow plugs and no difference, replaced the Battery and no difference. Fuel filter was replaced too.

I wonder if this is related to the SCV valves as other threads I seen on this website that have similar symptoms. Also I wonder if the glow plug relay could cause this?

If you measure the voltage between the glow plug and the ground (engine block), you should get 12 volts during the glow plugs warm up.  If the relay was not working well ( resistive contact or no contact) the voltage would be well below 12 volts.  This is assuming the Battery is delivering 12 volts.

The problem is the SCV. The short model, cheaper, causes this cold start issue when the outdoors temperature are below 15 C ish.   A tip to find out if the problem is related to the scv,  disconnect the fuel temperature sensor ,  try a cold start, it would start straight away.

The "good" scv is a Denso , longer version, it cost around £200.

Hi HSJ, thanks for your reply. Where is the fuel temperature sensor located? Would this flag up an engine light if the sensor is disconnected? 

Also if the longer Denso SCV is fitted, do I need the ECU updated with new Software? 

One thing I discovered to start the car without problem, i.e. only require one cycle of glow plug excitation, is to wait for about 5 seconds after the glow plug light goes out. So I know it is not a glow plug issue. So I do this until I find the root cause....

I am going to replace the fuel temperature sensor..... 

Anyone has a brand which they could recommend? 

Had seen some on eBay for £10, brand is Kerr Nelson. I never heard of...

Yes to close this thread with the solution. I replaced the fuel temperature and no differences to the starting.

I then discovered that I did not need to cycle the glow plug as this just add stress to the relay and wearing out the glow plug and also draining the Battery un-necessary.

The fix is to turn the key to position 2 (lucky that I have the key version!) and the glow plug lamp will come on and let it distinguish. Then I will wait for a further 5 seconds or when the fuel gauge shows up the levels. Then I crank the engine, and it will start with no issue. Every time even when it was like -2 deg C temperature.

So if people have starting issue when its cold or first thing in the morning, try the above. Don't go crazy and start replacing parts. I suspect the ECU circuitry need warming up and probably due to some sort of components drifts over time. I find this fix - waiting a few seconds are acceptable.