Hi,

I've just bought an I40 1.7D with FSH and low mileage (45k). The MPG is low (40 MPG) and the idle speed is sat at 1000 RPM.

I don't drive the car hard, if anything I bought it for its apparent good MPG (Hyundai claim 65 MPG). Whilst I don't expect 65 MPG, I do expect it to be better than my 150k miles 2001 VW Passat which sat around 48 MPG.

Any advice on correctional action or idle speed adjustment would be appreciated.

Best

Richard

 

Hi Richard,
Idle speed on your vehicle is controlled by the vehicle computer.
It may be affected by some conditions like a low battery where the system senses that and to compensate raises alternator output with a higher idle speed.

Also, if unmeasured air is getting into the engine, the system by way of the oxygen sensor picks up on that lean mixture and adds fuel to compensate, thereby raising idle speed.
With that in mind, just maybe it might be considered normal.