In an earlier contribution to this discussion,
> Bonnet Lock wrote:
>> With the curent cold weather, my (diesel) V70 (old shape) has been
>> running very rough for a bit after a cold start - so I suspected
>> that the glow plugs may not be operating.
> The heater plugs won`t affect running after starting.They are only
> energised for a few seconds prior to starting.
Not so! The following is the description given in VADIS of the glowplug
operation on the 2.5D engine:
If the ignition is switched on when engine temperature is below +5 °C, the
glowplugs are activated for a period which varies with engine temperature
and atmospheric pressure. The glowplug indicator lamp on the dashboard
indicates that preheating is active. Preheating shuts off when the engine is
turned by the starter motor.
After preheating stand-by heating is activated for up to five seconds. This
corresponds to the time between the glowplug indicator lamp going out and
the engine starting. This makes the engine easy to start even if it is not
started as soon as the indicator light goes out.
Start heating is activated for up to 30 seconds each time the engine is
turned over by the starter motor, if the engine coolant temperature (ECT) is
below +30 °C and engine speed (RPM) is below a given threshold. Start
heating facilitates engine starting even when it is not entirely cold.
Post-heating starts when the starter motor stops turning the engine.
Duration depends on engine temperature, engine speed (RPM) and quantity of
fuel injected. Post-heating is always shut off when engine speed (RPM)
exceeds 2500 rpm, irrespective of engine temperature and the quantity of
fuel injected. Post-heating is always activated even if preheating has not
been activated. This improves combustion which reduces noise levels,
improves idling and reduces exhaust gas emissions. Post-heating also
improves idling at extremely low temperatures.
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