[tfish]

When my trucks sitting in idle it frequently makes a sudden noise like its been reved, like the engine is going up a gear it gets louder then drops back down to the normal idle tick over.

Is this normal or indicate anything?


cheers

 

[Mark.]

The only strange noise i get sitting in idle is a drone in my left ear from the mrs

 

[chris vince]

This will happen quite normally, if the air con/climate control is working, the engine will increase revs slightly to compensate for the increased loading when the pump solenoid valve throws the pump in.
Chris