what mpg should i be getting with a full de-cat, blittz induction kit, dawes running a peak of 1.14 bar and also running optimax with nf?


i'm asking cause before the dawes i was getting a steady 28 mpg and right now(on my third tank since) i'm getting between 18 and 20 mpg.


RS6 material!!!...had to add that in there

 

It is somewhat easier to get through fuel quicker with a Dawes as it's much more on/off (more frequent use of high boost even when you're not intending it), but also I suspect there's a certain amount of 'fun factor' being thrown in here, isn't there? You're probably driving like it's your new toy, so the mpg will drop
Best thing to do to check - if you can manage - is drive like a wuss for a tank & see what happens. If your economy is still down, there's likely something else wrong (typically just a dodgy lambda sensor )

 

cheers bud. but to be honest i noticed the drop in mpg prettyu much straight away and have tried to keep the right foot fairly light on the pedal, although quite hard to do, but managing it anyway!! would the secs pick up a problem with the lambda sensor?

 

The problem with diagnosing the lambda sensor is you're using the dodgy sensor to diagnose the dodgy sensor!
You'd have to get values from someone else (I'm not sure what they should be ) but as long as your MAF is working, there is a particular (smallish) range of values that the lambda should read under WOT, ie when the lambda sensor is actually not being used to control the mixture. I think it's around 0.92-0.94v, but am not at all sure! A lambda will start reading under, so the value will drop to e.g. 0.88v under WOT (which would also be what a dodgy MAF would read, hence the problem...) but repeated blasts will heat the sensor up, this also reducing the produced voltage.
My guess is it's still a heavy right foot