ard-tullaich · Dec 10, 2014

Hi all just finished restoring my 1997 300 tdi disco .Noticed i havent got a fast idle on cold start if any thing its lower and sits at 720 when warmed up . I thought it would sit at around 1000rpm on a cold start.
Any one got any ideas

discool · Dec 10, 2014

That is it for a tdi, 720rpm +- 20rpm.

ard-tullaich · Dec 10, 2014

so you saying 720 normal tickover but what about a cold start ?

robbh · Dec 10, 2014

ard-tullaich said:
so you saying 720 normal tickover but what about a cold start ?

The same.

Mine ticksover over at the same speed no matter if it's hot or cold.

Cold start is in the form of glow plugs which heats up the combustion chamber for a short time before starting (or something to that effect anyway) . Although it isn't cold enough to warrant the use of them yet. Mine still starts first flick of the key every morning.

ard-tullaich · Dec 10, 2014

robbh said:
The same.

Mine ticksover over at the same speed no matter if it's hot or cold.

Cold start is in the form of glow plugs which heats up the combustion chamber for a short time before starting (or something to that effect anyway) . Although it isn't cold enough to warrant the use of them yet. Mine still starts first flick of the key every morning.

mine to starts straight away on the first turn just remember reading some where of a fast idle on cold start just like auto choke on a petrol motor.

discool · Dec 11, 2014

Do u not think u may had drifted onto a petrol engine thread as u are right "fast idle" applies to petrol engines, manual or automatic choke for carburettor engines as Efi engine don't have a choke.

ronsealdeath · Dec 11, 2014

No he's saying when cold it idles low until warm. Just like my disco does. Not glow plugs, not leak off pipes and not dirty injectors. I have a new lift pump to try which I hope solves this. Diesel leaking back from some seal issue somewhere causing a lean mix for a minute when cold maybe. In summer it was fine only shown its head now in cold weather
The bosch inj pump has a cold start advance on a disco that advances timing when cold. Thermistor in coolant turns it off when engine warm. This is another suspect but means a new inj pump if its goosed. Unlikely tho I suspect more likely air leak sonewhere

discool · Dec 11, 2014

ronsealdeath said:
No he's saying when cold it idles low until warm. Just like my disco does. Not glow plugs, not leak off pipes and not dirty injectors. I have a new lift pump to try which I hope solves this. Diesel leaking back from some seal issue somewhere causing a lean mix for a minute when cold maybe. In summer it was fine only shown its head now in cold weather
The bosch inj pump has a cold start advance on a disco that advances timing when cold. Thermistor in coolant turns it off when engine warm. This is another suspect but means a new inj pump if its goosed. Unlikely tho I suspect more likely air leak sonewhere

I'm taking it as the title of the thread, therefore we have the base idle speed but on a cold start the RPM increases.

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