Hi, I read the whole thread, but I must admit that I got lost in it. If this is not a problem, would anyone be able to tell which maps to what values should be set initially for BOSCH 0 280 158 123? The flow from what I can see is 627 at 3 bar and that's what I stay at.
Will these values be suitable as baseline for a possible correction?
Bosch EV14 ~ 630 cm3 at 4 bar (550 cm3 at 3 bar)
KRKTE: 0.05745
TVUB: 3.364, 1.572, 1.128, 0.854, 0.568
FKKVS set to 1
I can't speak to these values, but generally speaking to get started:
new krkte = original KRKTE * (new injector flow / old injector flow)
if you have appropriate values for TVUB from a datasheet, you can either interpolate them if the voltages don't match, or change the axis on TVUB to make them match.
Set FKKVS to 0, drive around long enough for the car to adapt. Tune TVUB and KRKTE off of the idle adaption and multiplicative adaption (fuel trims).
Tip in / tip out enrichment may need to be adjusted too. Basically just follow PRJ's advice in the quote below. That process worked wonders for me, just make sure you reset adaptation after you make a change, otherwise you end up chasing your tail.
Since I pretty much do not tune anymore, here's some info on how to scale aftermarket injectors, when you have no datasheet for them.
Let's say you have injectors on the car for which you do not have any clue what the TVUB could be, maybe you're not 100% on the flow rate either.
Let's assume for the moment that everything else on the car is linearized - because if not, then good luck to you. It is still doable, but without a huge amount of experience and knowledge you will not find out what's scaled wrong, so it is outside the scope of this topic.
Also before starting, pressure test the car and make sure there are no air leaks whatsoever anywhere, otherwise you're gonna have to do this all over again after fixing the leaks.
1. Set FKKVS to 1 everywhere.
2. Set KRKTE into the ballpark that you think it could be. By far the easiest way is to divide the OEM injector size by the current injector size and multiply KRKTE by this number, instead of trying to do theoretical calculations.
3. Take TVUB from some random injectors, that are at least the same type - e.g. EV6, EV14.
4. Start the car, if it doesn't start, you probably messed up really badly, so try to correct your error (or remove and clean the sparkplugs if you totally flooded it).
5. Let it warm up fully, so it's completely hot and there is no load on it.
6. Find KRKTE value so that you have more or less 1-2% fuel trim on idle with the hot engine.
7. Put some load on the engine, e.g. turn on the aircon, rotate the power steering, slip the clutch a little, put it in D if it's an auto instead of P/N, whatever. Observe what happens.
a) If the fuel trim goes positive, increase KRKTE, decrease TVUB at the voltage where you are testing (or just multiply the whole table), so FT is still good on idle, but does not drift away on load.
b) If the fuel trim goes negative, decrease KRKTE, increase TVUB at the voltage where you are testing (or just multiply the whole table), so FT is still good on idle, but does not drift away on load.
Usually it is good to change TVUB in 2% increments. Repeat this process until it's more or less stable, then proceed to 8.
8. Set the car on idle, fully warmed up. Increase the RPM, to 3000, then 6000 rpm without any load on the engine.
a) If the fuel trim goes positive, increase TVUB, decrease KRKTE to compensate, so that you still have good fuel trim on idle.
b) If the fuel trim goes negative, decrease TVUB, increase KRKTE to compensate, so that you still have good fuel trim on idle.
Repeat this process until you can slowly increase the RPM on hot idle and the fuel trim doesn't drift away.
And you're pretty much done. The rest compensate using FKKVS. Beware of large changes (more than 5% on high RPM), this most likely means your fuel pressure is dropping -> verify with a fuel pressure gauge.
Make sure you do not make any sudden movements/load changes, as your tip-in/tip-out enrichment might not be correct - those can be adjusted via KFBAKL/KFVAKL by making sharp throttle movements and observing what actual lambda is doing, but only after you have set KRKTE and TVUB correctly.
