Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
Pretty well any diesel that has been idling for a while - or driven
gently - will smoke badly when pushed. Hence the way the MOT is done
for diesels.

Is that true for direct injection though?

No build up of fuel in the manifold etc..

Aren't pretty well all diesels direct injection? You compress air to a
high pressure and therefore temperature then squirt some fuel into the
combustion chamber which causes the bang?


Nope. Lots squirt it into the inlet manifold I think.

Ah. always find someone who knows more..looks like I was half right.
Neither the inlet nor the cylinder..


http://en.wikipedia.org/wiki/Indirect_injection

Direct injection is fairly new with common petrol cars, but not diesels.
Perhaps you're thinking of common rail where an actively powered injector
times the injection under the control of an ECU, rather than the older
pump?


I was actually thinking of an ancient tractor..wheer the glow plug was
in the inlet manifold, and the only way to start it sometimes was to
open that up, and pour a cupful of diesel into it, and then if that
didnt catch fire, shove a rag in it and light it..I cant remember if
that had direct injection or not..


Model aircraft diesels use no injectors at all..but do require ether in
the mix to ignite it.