Discussion and questions related to the course Diesel Tuning Fundamentals
can someone please explain the fuel quantity map and what effect they have. From what I understand the only way to get more fuel in is via rail pressure or physically opening the injectors longer so I don’t understand the fuel quantity maps and why I should adjust them
The fuel quantity map defines exactly what it's name implies - defines the quantity of fuel that will be delivered. Increasing the fuel pressure can increase the fuel delivery if the injector pulse width remains the same and this is a common hack that's used by a lot of the piggy back modules. With complete control over the factory calibration we can directly request more fuel with the fuel quantity table. We usually also increase the fuel pressure so that the injection timing and pulse width remain relatively similar to stock.
Hello i was about to start a new thread with similar question, so i am glad that i went to check the existing ones first. So basically from what i uderstood rail pressure or fuel pressure is usually increased when we want to inject more fuel, without changing the start of injection and duration?
Also about SOI and Duration maps. I saw a thread where someone was asking for a formula to calculate the change in SOI and duration, when changing the requested fuel injection. Is there such formula, i mean on engineering level? My understanding is when reflashing an ECU we already have values in the tables from the manufacturer. So for example if we get injection quantity values at certain rpm and compare them to start of injection values and duration values at the same rpm, the increase in soi and duration for 1 mg of fuel can be calculated and then those values can be used for the new requested injection quantity?
Simply put example:
At 4000 rpm and 60mg of fuel we have lets say 15* BTDC soi and 60 uS duration = 0.25*BTDC soi and 1uS duration on 1mg of extra fuel. So at 61 mg we would need to change Soi to 15.25* BTDC and druation to 61 uS?
There seems to be many different ways to skin a cat or tune a diesel and I have tried about 100 different flashes to my ecu.
When increasing mm3 in the fuel quantity maps I have found it changes what torque the engine is seeing, higher mm3 shows lower Torque when scanning, so I’m not sure if this is the best way. It’s best for an auto trans to see any increase in torque made.
I have found on my GM 2.8 after a lot of experimentation that an increase to the requested torque map gives more mm3 at what ever rpm you want it at and it seems to drive really nice, not many other maps need to be edited either.