Engine management

[CJN]

A few months ago I dropped a K&N airfilter into the standard airbox in my S1 Elise. This increased fuel consumption by 10-15% & gave a little more top end. I swapped back to the old standard filter & the fuel consumption seems to have got worse, if anything. I did this because I'd read that during idle (most of the time on the way to work) not all of the fuel is always burnt which can cause CAT damage. I'm now seeing 30 on a run as opposed to 36-37 originally. The tailpipes are sooted a little but they were like this from day one of my ownership.

Please help me, does the engine management want re-setting & can any Rover dealer do this or is it a Lotus only job? or something else?

CJ

[AER]

It may not be the air-box mod. If you really haven't changed your driving style, or the traffic hasn't got dramatically worse (most significant factors that affect FC), then check your HEGO sensor hasn't fallen off.

Mine, on a 60k 96P, has definitely fallen off and the fuel consumption has dropped by about 4-5 mpg, not all of which can be attributed to this.