Start up engine speed

[ucb]

Audi A1 tdi. At start up the engine speed is 800rpm. I am sure that this should be above 1000rpm and slowly reduce as the engine warms up?

Maybe connected to this is that sometimes, until the engine temperature rises a little, there is a slight "miss fire".

What sensors control the engine at start up?

 

Thanks.  

[Stevey Y]

2 hours ago, ucb said:

Audi A1 tdi. At start up the engine speed is 800rpm. I am sure that this should be above 1000rpm and slowly reduce as the engine warms up?

Maybe connected to this is that sometimes, until the engine temperature rises a little, there is a slight "miss fire".

What sensors control the engine at start up?

 

Thanks.  

Hi there are no sensors that control the start up its all controlled by the ECU, so any adjustments to the fuelling and air/injection cycles are monitored and fine tuned from there, its all to do with emissions in the old days when there was an enrichment device [choke] the engine would run at higher rpm because the airflow was restricted and the fuel increased, this also increased Hydrocarbon output, these days with the advent of Piezo injectors which can inject or decline to inject up to five times in one cylinder cycle the fuel air ratio is precise and the Hydrocarbons drastically reduced, therefore there is no need to have higher idle at start up, the way its all structured means the engine gets up to running temperature in double time with out the added pollutants.

Steve.

[ucb]

Steve

 

Thanks for the technical information, that all seems to fit together and aids my understanding. Many thanks