Reply To: How Do Diesel ECM's Typically Calculate Fuel Burn and Engine Load

[Nicholas]

Thanks. Your statement about accuracy gets to the crux of my issue – which is the ongoing mystery i’ve been trying to figure out as to why one of my motors appears to be burning ~15% more fuel (with correspondingly higher engine loading) than the other. I’ve gone through everything I can possibly think of – ruling out props, running gear, intake leak/inadequate boost, EGT differences, etc..

The way the topic came up was I relating my situation to a cummins tech at a boat show, wondering if my next step should be to pull the head and have a look inside. He told me since the EGTs matched, i’d ruled out props and/or misalignment, not getting much if any smoke except at startup and initial throttle up, etc., he thought the most likely explanation was that for ~15 year old engines it’s just not calculating the fuel burn very accurately. He told me about how it was calculated, not measured, which I wanted to check up on.

But it sounds like your experience is the fuel burn, despite not being measured directly, is pretty accurate.