Thread: Interpretation of Recorded Data - Nanocom

Is there a knowledgeable member that is able to provide an insight to the interpretation of air flow, fueling data, lamda etc as recorded using a Nanocom Evo for a D2 auto V8.

I am attempting to understand why I have experienced an increase in fuel consumption of around 30% for highway travel cruising at 110kmh on the Hume between Melbourne - Wangarrata return. I used to consistently average 14 L/100 km, now 19 l/100km.
New Iridium plugs, new MAF, new O2 sensors.

Running 91 octane std grade fuel. I had, prior to the deterioration of the fuel economy conducted runs using variously 95 & 98 octane on the same journey with no appreciable variance. ( Max variation 0.1 to 0.2 over 6 runs)

NOTE Please note Engine is Low Compression 8.23:1

First check thats is entering closed loop.

Then look at the O2 figures - pre cat. Should switch approx 0.1V to 0.8V (assuming they are narrow band which I'm sure they are) on cruise warm They should switch at a minimum of 1Hz.

Also check your fuel trims. Mainly Long term (LT).

That will give you a good idea on whats going on regarding fuel control.
MAF figures are extremly hard to interpret alone. Minimum voltage <0.2v is the differance between a rich or lean stall at idle. A MAF may report fine in one area and not in another.
Injection duration is also only a pointer to possible faults. I usually expect to see about 2.8ms (not LR specific) warm, idle. Again only of limited use.


Approx 0.8V wide open throttle.


HTH