I have been keeping a record of my fuel consumption for the 3 years since having my MY97 Turbo, bog standard except for K&N filter and have been averaging 24 mpg with very little variance. Lately, the consumption has gone up by at least 10% for no apparent reason. Didn't touch anything except when changing the rocker cover gasket recently, the induction housing along with the air fuel sensor, and the boost solenoid wiring were removed and fitted back. (I have a heat shield that separated the induction kit from the rest of the engine bay) Also changed the front brake pads, but that was before the increase. No check engine lights so far, tyre pressures were OK, and air temperature is same year round. Any ideas? Will be bringing the car to the dealer to be diagnosed by their select monitor, anything to look out for?
Thanks.

 

Are your new pads not contacting the discs during driving ?

 

griffm, the wheels were rotated while the car was up on jacks and the pads were not gripping. Forgot to mention the front off side inner drive shaft boot was knackered and was driving around in that condition when consumption increased, but could this be the cause? When changing the boot (got to wait 1 month for the part to arrive from Japan), noticed that part of the grease was gone, but the bearings were still covered and the mechanic said no major damage was done.

 

When the rocker cover was changed, did the battery get disconnected?
I also monitor the fuel consumption and noticed that after a service the fuel consumption was worse. The dealer had been restoring the factory ecu settings rather than using the figures that were "developed" by driving the vehicle around.

 

Have you cleaned the K&N filter lately? The oil used in the filter can affect the MAF sensor. Do a serch for MAF on this site and you will get a lot of info on this problem.

 

Mikey, the battery was not disconnected this time. Earlier, I had a battery change but there is no observed effect on consumption then.
Firefighter, I have not cleaned the filter recently. When it was disconnected during the rocker cover repair, I had a look at the AF sensor and it was clean, so didn't do anything to it. Anyway, the filter is not due for another cleaning yet.