My 2002 TD4 (125k) has been getting a bit lazy to start when cold. Purchased a new set of Glow Plugs and made no difference.

Have been monitoring the glow plug feed and it does a weird thing.
When car starts o.k then 10-11v appears for about 15 seconds then goes - as expected. Interesting teh light on the dash is alight for a much shorter period.

When car refuses to fire (and does eventually amidst white smoke) even from cold, no voltage appears on the glow plugs until it fires and then 12v appears for around 20-30 seconds !!!

Have ordered a new temperature sensor as it is cheap and easy to do, but has anyone worked out how and why the power arrives after starting?? Any other reasons why the feed is not present every time from cold?

Thanks

The ECU measures engine coolant temperature to see if the glow plugs are needed, it also measures the battery voltage to see if it has enough voltage to power the glow plugs before starting and lights the glow plug light for the pre start warm up. If the battery voltage is too low, it will not use the pre start warm up.
The glow plugs are powered for a period after starting to reduce smoke.
It could be your battery is on its way out.

andyfreelandy said:

My 2002 TD4 (125k) has been getting a bit lazy to start when cold. Purchased a new set of Glow Plugs and made no difference.

Have been monitoring the glow plug feed and it does a weird thing.
When car starts o.k then 10-11v appears for about 15 seconds then goes - as expected. Interesting teh light on the dash is alight for a much shorter period.

When car refuses to fire (and does eventually amidst white smoke) even from cold, no voltage appears on the glow plugs until it fires and then 12v appears for around 20-30 seconds !!!

Have ordered a new temperature sensor as it is cheap and easy to do, but has anyone worked out how and why the power arrives after starting?? Any other reasons why the feed is not present every time from cold?

Thanks

Click to expand...

Could you advise me which sensor you have ordered, mine does this and I have wondered if it was the battery but would like to replace the sensor anyway.

Hi, thanks for thoughts. My car does (every 3 months or so) fail to start with the starter not engaging. I am wondering if there is a bad connection that is also the source of the voltage reference for the 'glow plug' decision maker !!! Maybe it sees low battery when not low at all??

I have ordered one of these.
http://www.ebay.co.uk/itm/252338812389?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
It is under the inlet manifold though and bit tricky to change.

The PTC heater is on the fuel pump circuit, so if the heater fan is on and the heater knob on warm, the battery will have to power that and the glow plugs on pre start warm up. Try turning the heater fan off before turning the ignition on for a cold start.

So - update. Removed all glow plugs again. Tested on battery. Refitted and now working correctly ! Weird !
Think the odd 'non-catching' of starter is probably burnt solenoid contacts as battery voltage stays fine when it does it. have ordered replacement contacts.

So - will monitor glow situation but removal and burning (they were new) has solved problem. Perhaps they are coated and need to be used before installation?? Not sure why this would stop voltage appearing (it wouldn't) but maybe with the complex arrangements for firing the plugs I mis-read the symptoms?? Still maybe a possible ba connection - the coolant sensor is near the plugs and so this will get a better check up when I replace sensor. Be nice to find something - hat intermittent faults and the TD4 seems to be able to generate them at will.