PCV cheating the fuel consumption (even more)

[martin_14]

A lot has been said about the fuel consumption of the C14 and many other bikes but, as someone pointed out, it's pretty simple, really: when it's running low, put more and go back to enjoy driving this wonderful machine. Not much to think about it.

That said, I keep a track of the fuel consumption of my bike and I came to know that the board computer lies by about 1.5 or 2 mpg. That is, when the bike is doing 40 mpg, computer will show 42. I did this on short trips, long trips (several thousand miles), hot or cold weather. Solo or with girlfriend and luggage. Results are around the same.

Now I have the PCV and flies out, and the consumption dropped by about 2 mpg according to my notes, but the computer says that the drop has been an extra 3 mpg, that is, now it is lying a lot, by 5 mpg.

My scarce knowledge is telling me that the computer calculates the amount of fuel being used by the signal that the ECU sends to the injectors, not what they actually inject, which is altered by the PCV. Hence, since the flies are off there is more air (and fuel, as dictated by the PCV) coming in to the engine at the usual RPMs (3000-5000) than what the ECU thinks.

Is this plausible?

I really think that the programmers at Kawasaki did a lousy job on the mpg calculation. As an example, if you turn off the engine and coast down a hill the display still shows 2.5 lt/100 km (sorry, I'm in Europe, but it equals about 94 mpg!!!), which is still a lot if the engine is actually off.

All in all, I'm really happy driving fly-less and the 1400 cc that I paid for are now there off the line, not just above 6000 rpm. The bike is more responsive, more direct to my right hand. I need less input to get her moving and she reacts quicker. Now I just have to tune that map to polish, if possible, the off-on throttle response and I'll be satisfied.

[Elfmaze]

the on off throttle thing is my biggest complaint right now.  in tight technical turns she is defiantly jumpy. 

[jjsC6]

When I put a PCIII on my FJR a few years ago the exact same thing happened.  My actual mileage dropped nearly 10%, but my average fuel mileage readout on the bike read the higher mileage that it got before.  You are correct in your assumption.  Today's average MPG readouts are based upon how much fuel is being metered by the ECU.  It does not know that you have tricked it into sending out more fuel.

[lt1]

Martin, I believe you are correct.  My 08 always reports better fuel economy on normal to heavy usage.  OTOH, I had a few tanks with extremely light throttle use (all highway, low speed) that I actually got better mileage than shown by the computer.  IIRC, computer showed about 50-52 and the calculations showed 52-55.

Now, I still write down the computer mpg (reset each fill-up) and the calculated mpg down on my reciepts, but it is just out of habit and for amusement.  I keep the display on tire pressure, and don't worry about/look at the mpg/range screens.  I keep an eye on the trip mileage, and calculate remaining range when the reserve light comes on.

[VirginiaJim]

+1