C320 petrol, fuel consumption.

[Chalpkin]

My C320 petrol has started drinking fuel at an alarming rate. It used to average between 16 to 20 around town and up to 33mpg on a long run, but now it's down to 9 to 13 in town and up to 25 on a long run, it's just had a A service and gearbox oil and filter change. I also changed the Maf (Bosch), as on STAR the original was showing as faulty. The car runs as smooth as silk, with no coughs or splutter's. What's going on?
Chalpkin.

 

[martyz]

Thermostat not holding eng temp& fueling for a cold engine?

 

[Chalpkin]

Thermostat not holding eng temp& fueling for a cold engine?

No, the car warms up fine!

 

[DSM10000]

What is the temperature reading when warmed up? It should be close to 90 degrees C

If not the thermostat then probably a lambda sensor is faulty.

 

[Chalpkin]

What is the temperature reading when warmed up? It should be close to 90 degrees C

If not the thermostat then probably a lambda sensor is faulty.

Yes, it reaches 85-90 degrees after about 5 miles.
Will the lambda sensor show up on STAR?

 

[DSM10000]

Yes, it reaches 85-90 degrees after about 5 miles.
Will the lambda sensor show up on STAR?

It should, a decent OBD reader can also give lambda values but Star is a better bet for a full diagnostic!

 

[Chalpkin]

It should, a decent OBD reader can also give lambda values but Star is a better bet for a full diagnostic!

Hi,
It went on STAR when it was serviced, that's how we found out it needed the new Maf, the technician said that was the only fault shown!
Chalpkin.

 

[DSM10000]

Hi,
It went on STAR when it was serviced, that's how we found out it needed the new Maf, the technician said that was the only fault shown!
Chalpkin.

Perhaps this fault has arisen since then or the technician did not run a full diagnostic?

 

[martyz]

Might be an idea to remove the aux belt and check everything on it rotates freely,
not putting any undue load on the engine,also check road wheels for brakes binding,
apart from the obvious,leaking(weeping) sometimes hard to detect until flexed fuel hoses.