Help Engine Noise

November 26, 2009

Can any one help? I am the owner of 2003 Toyota hiace with the 2.5 d4d engine witch has a rattling sound on light throttle low revs, then the sound weakens if more throttle is applied and again the sound comes back on lifting off but only for couple of seconds. I think its injector but not sure any help would be good.

November 26, 2009

It's not a problem as such.

The likely reason it they do it is due to the D4D two stage injector fire when cold, some do it some don't, maybe to do with ECU programming and self learn function.

I believe it is to do with meeting emission targets, maintaining smooth idle and ease of starting when cold.

People are getting concerned due to the rattle that is in most CRD engines when cold as some are louder then others, they are working in excess of 20,000psi injection pressure.

Remember they don't have any pre heating.

During the second phase of diesel combustion all the fuel that has accumulated and formed stoichiometric ratios during the delay period (1st phase) will suddenly ignite and burn explosively.

When the engine is cold or it is cold outside more unburned fuel will accumulate before the combustion temperature is reached resulting in a bigger BANG due to the increased delay period. This is the characteristic "cold knock" you will hear on a diesel on a cold morning.

If in doubt give Mr T a quick bell

November 26, 2009

It's not a problem as such.
The likely reason it they do it is due to the D4D two stage injector fire when cold, some do it some don't, maybe to do with ECU programming and self learn function.
I believe it is to do with meeting emission targets, maintaining smooth idle and ease of starting when cold.
People are getting concerned due to the rattle that is in most CRD engines when cold as some are louder then others, they are working in excess of 20,000psi injection pressure.
Remember they don't have any pre heating.
During the second phase of diesel combustion all the fuel that has accumulated and formed stoichiometric ratios during the delay period (1st phase) will suddenly ignite and burn explosively.
When the engine is cold or it is cold outside more unburned fuel will accumulate before the combustion temperature is reached resulting in a bigger BANG due to the increased delay period. This is the characteristic "cold knock" you will hear on a diesel on a cold morning.
If in doubt give Mr T a quick bell

Cor blimey, Guvnor :o He's all technical as well as a smart a........................lec :eek: :laughing: