Got a vrs on a 54 plate, ive recently noticed when waiting for the bloody thing demist on our cold wintery mornings!❄️🌧 when holding the revs at 2400 rpm they fluctuate on there own like an air leak on a petrol.

Anywhere else in the rev range it doesnt do it. 

Idles fine etc etc no fault codes. 

It does it when the engine is up to temp to.

The car is standard. 

I have put our snap on scanner on it on data logger but the thing is crap and i dont trust it! 

The only thing i could see was IAT 2 was reading 21degrees when outside temp was 3degrees. 

Like said i dont trust the scanner as  it can give multiple sensor readings when i know the car doesnt have them! 

Anyway ive linked a video anybody any thoughts? Tia Damien

Edited 23 November, 20196 yr by Damo152003

Right after a bit of investigation i have found what is causing this.

its the vacuum box causing the egr valve to open and close at that given rev range. 

Tested the egr valve with a miti vac and the all good so a new box is required.