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Injection timing

Diesel Tuning Fundamentals

Discussion and questions related to the course Diesel Tuning Fundamentals


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Hi andre or anyone else that may tune in that could help answer a question. From watching the tuning fundamentals course y oh u jumped into effect of timing on afrs. I am going to tune the exact same car as you used in the demonstration but custom write a file to reprogram the ecu. What I want to know is what sort of max timing advance would you aim for on that vehicle. Would you play with the whole map or only the light load areas etc. My issue is I am going to road tune it as I do not have access to a dyno and trying to gain power and economy at cruise.

From what I can gather is that increasing the timing you create a larger peak cylinder pressure and earlier in crankshaft degrees and by doing that you can use less mg/st to achieve the same hp/tq for a later injection timing but to tune this on a dyno would you increase timing until maximum braked torque is achieved if you have access to one ?

is this anywhere close for my understanding ? I believe that the 1kd engines are too far retarded from factory to try lower nox and meet emission standards as I have found by increasing rail pressure or duration they will rattle until engine temp has reached running temps. I personally think they could do with more timing to help reduce this but I could be wrong please anyone tune in and give me some of your answers to help me understand if I am on the right path or not thankyou

Hey Ryan, there's a few things to consider here. Firstly even with the stock fuel mass there can be advantages to modifying the injection timing. This becomes more important when you want to also add more fuel because with the stock injection timing and a longer pulse width, the injection happens further into the engine cycle. As a rough guide you're probably going to want to try delivering between 40-60% of the fuel BTDC but the dyno is the best way of figuring out exactly what your particular engine wants. It's hard to put specific numbers around injection timing as it will vary for every engine and also clearly depends on the injector pulse width and engine speed. I'd suggest you cap timing at perhaps 27-28 degrees at high rpm though.

In cruise conditions you can find an improvement in economy by advancing the timing from the stock values. You're correct that the stock timing is more focussed on emissions than economy.