C4 1.6 Petrol Fuel Consumption

[paul.h]

Posted on behalf of c4_man.

 

I need some help with my c4. Last week I have noticed that fuel consumption is pretty high. When driving on pretty flat road with cruise on, then on board computer shows 10-11 l/100 km (= 28.4 - 25.8 mpg). Before that it was around 9 l/100 km (= 31.6 mpg), but this is also a lot. I replaced air filter and spark plugs. What else to check? No fault codes present.

 

The car is a 2005 C4 1.6 litre 80kW (110 hp) non VTi petrol engine.

 

 

[paul.h]

First questions:

 

- what speed are you doing at these fuel consumptions ?

- is the gearbox a manual or auto ?

- do you reset the trip computer before doing the test ? This is so that it is not giving an average of all the previous trips which might include a lot of stop/start driving round town. It is reset by holding in the button on the end of the wiper stalk.

 

The Haynes manual for the C4 gives the following possibilities for high fuel consumption:

- air filter dirty or clogged

- engine management system fault

- faulty fuel injectors

- tyres under inflated

- brakes binding

[c4_man]

Usually I drive 90-93 km/h and car has manual gearbox. For the fuel consumption I use full tank-empty tank-full tank method, but on board computer shows same, difference is 0,1 l/100 km or less.

 

I will check brakes. Air filter is replaced and tyre pressure also ok. Engine management and faulty injectors should give fault code.

[c4_man]

Right rear brake caliper was stuck. I removed it and got the piston out. Cleaned it, but I do not understand how to clean the caliper side. How to remove this inner threaded part?