Consumption function

Could somebody please explain how each of the 2 fuel-o-meters work, and their relative accuracy. I have the updated trip computer from '84 on.

Where do each of these take their info from, and does the computer regard enriched running when the car is cold e.t.c e.t.c?

I have always thought that the one below the tachometer is not really worth looking at unless you are cruising at a sensible speed.

m3Cecotto wrote: phb10186 wrote: but where is it taking the reading from, and what is it measuring? Induction vacuum I believe, but how valuable that is in terms of measuring fuel economy is beyond my ken.

it is also related to road speed/ engine rpm as well;

induction vacuum is related to throttle opeing and hence fuel consumption BUT only if the engine is at constant temperature. Thus the readings are only evenremotely accurate if your engine is fully warm and your injection system is working properly.

I believe the OBC reads injector pulses; not sure if it reads the cold start injector as well or not.

cheers