"Blocked" airfilter on 300Tdi

[B92 8NW]

What is the reason behind an observed increase in fuel consumption when the air filter is carrying a high dust load?

I was reading a rather comprehensive post by JDNSW which mentioned that the housing/filter is designed for minimal restriction at maximum rpm on most diesels. Added to the fact that the engine is turbocharged and there isn't an ECU or MAF sensor to make any fuelling changes, what causes the MPG suffer?

[camel_landy]

I would say that the blocked filter is causing your right foot & the turbo to compensate and work harder.

This combination will make the compensating mechanisms in the fuel pump (remember it's mechanical rather than electronic) deliver more fuel into the mix.

M

[isuzurover]

What is the reason behind an observed increase in fuel consumption when the air filter is carrying a high dust load?

I was reading a rather comprehensive post by JDNSW which mentioned that the housing/filter is designed for minimal restriction at maximum rpm on most diesels. Added to the fact that the engine is turbocharged and there isn't an ECU or MAF sensor to make any fuelling changes, what causes the MPG suffer?

The engine has to do more work to move the same amount of mass (the vehicle) the same distance at the same speed.

A bit like the difference between driving with the AC on or not.

I am surprised you can notice the difference in a diesel though. The filter must be VERY dusty.