Pulling a bow back three quarter then fire is analogous to a engine with spark plug and ignition system. Taking it all the way back using the full potential gives cleaner and more powerful shot. Auto-ignite pressure point is the cleanest burn with most power. If compression ration is to high with four stroke engine, premature detonation, knocking can be a result, destroying the engine. With this setup it is just a case of when it will ignite, and ignite it will. Most emission test instruments in use would not give a reading if petrol is burned proper. The value be to low, out of range. Diesel is more or less oil and the only major difference to heating oil is tax rate in some countries. Even 2-stroke burns cleaner as Diesel as only some oil is used and not 100% Premature firing is not the way to go, time for change. Below, both hydrogen flames use 200 watt of power. The left side burns so bad and extinguishes, just enough time to make a photo. The right side on the other hand burns as clean as about can be, nice blue flame. The only difference is nozzle size and consequently pressure its burning at.