F55/F56 BMS stage 1 + Exhaust Mod?
#51
#52
CobraBob I completely agree with the premise of your statement, even though I am not too sure what a wide band is (I'll google). I REALLY want to understand what the different settings are actually adjusting and how they affect my engine, but I can't seem to find that info anywhere - just people saying things like "set it to 50" or "set it to 60." The other forum link that people post when I have questions doesn't really go into what the settings actually do either.
there are 2 ways to enhance the amount of fuel injected of such engines:
- raising the injectors opening times (by flashing the DME, the JB4 don't do that).
- raising the fuel pressure in the injectors rails (Open loop fueling) by the HPFP.
open loop or closed loop are 2 states of the lambda sensors adjustment.
when the engine is on closed loop state, (ie low throttle for example), the DME reads the lambda value to adapt the trimings.
when the engine is on open loop state (ie Wide Open Throttle), the DME no more reads the lambda sensor value and is injecting fuel as the map on the DME is calibrated, without any adaptation of trimings.
Open loop fueling is a JB4 function which allow the HPFP (high pressure fuel pump) to enhance the fuel pressure in the injectors rail, in order to enhance the fuel amount injected when the engine is at WOT, where there is a lot fuel needed, to keep you AFRs rich enough.
by default Map 5 have an auto-adaptative Open loop fueling.
but we can set it manually (futureuseB=2 with iso boards) if we have 29F2 limp mode code which indicates the OLF setting is too high.
lowering the OLF setting manually will put less stress on the HPFP, avoid 29F2 codes, but will lead to highers trimings.
If trimings are maxing out (IE >50 on the JB4 log graphs), it's not good too, as the DME can't control the fuel amount.
#53
copied and pasted from n54tech general help sub-forum (not specific to our car):
there are 2 ways to enhance the amount of fuel injected of such engines:
- raising the injectors opening times (by flashing the DME, the JB4 don't do that).
- raising the fuel pressure in the injectors rails (Open loop fueling) by the HPFP.
open loop or closed loop are 2 states of the lambda sensors adjustment.
when the engine is on closed loop state, (ie low throttle for example), the DME reads the lambda value to adapt the trimings.
when the engine is on open loop state (ie Wide Open Throttle), the DME no more reads the lambda sensor value and is injecting fuel as the map on the DME is calibrated, without any adaptation of trimings.
Open loop fueling is a JB4 function which allow the HPFP (high pressure fuel pump) to enhance the fuel pressure in the injectors rail, in order to enhance the fuel amount injected when the engine is at WOT, where there is a lot fuel needed, to keep you AFRs rich enough.
by default Map 5 have an auto-adaptative Open loop fueling.
but we can set it manually (futureuseB=2 with iso boards) if we have 29F2 limp mode code which indicates the OLF setting is too high.
lowering the OLF setting manually will put less stress on the HPFP, avoid 29F2 codes, but will lead to highers trimings.
If trimings are maxing out (IE >50 on the JB4 log graphs), it's not good too, as the DME can't control the fuel amount.
there are 2 ways to enhance the amount of fuel injected of such engines:
- raising the injectors opening times (by flashing the DME, the JB4 don't do that).
- raising the fuel pressure in the injectors rails (Open loop fueling) by the HPFP.
open loop or closed loop are 2 states of the lambda sensors adjustment.
when the engine is on closed loop state, (ie low throttle for example), the DME reads the lambda value to adapt the trimings.
when the engine is on open loop state (ie Wide Open Throttle), the DME no more reads the lambda sensor value and is injecting fuel as the map on the DME is calibrated, without any adaptation of trimings.
Open loop fueling is a JB4 function which allow the HPFP (high pressure fuel pump) to enhance the fuel pressure in the injectors rail, in order to enhance the fuel amount injected when the engine is at WOT, where there is a lot fuel needed, to keep you AFRs rich enough.
by default Map 5 have an auto-adaptative Open loop fueling.
but we can set it manually (futureuseB=2 with iso boards) if we have 29F2 limp mode code which indicates the OLF setting is too high.
lowering the OLF setting manually will put less stress on the HPFP, avoid 29F2 codes, but will lead to highers trimings.
If trimings are maxing out (IE >50 on the JB4 log graphs), it's not good too, as the DME can't control the fuel amount.
So where are people getting that you want 50 if you're using a flex fuel cable and 60 otherwise? What's the max pressure you could safely put on the fuel injector rails? How does Octane play into this? It sounds like there's a built in fault code that lets you know if you are putting a setting open loop too high.
#54
Wow. Thanks for that... I guess I was searching for info specific to my make.
So where are people getting that you want 50 if you're using a flex fuel cable and 60 otherwise? What's the max pressure you could safely put on the fuel injector rails? How does Octane play into this? It sounds like there's a built in fault code that lets you know if you are putting a setting open loop too high.
So where are people getting that you want 50 if you're using a flex fuel cable and 60 otherwise? What's the max pressure you could safely put on the fuel injector rails? How does Octane play into this? It sounds like there's a built in fault code that lets you know if you are putting a setting open loop too high.
i can only guess that some of these guys have been playing with BMS kits in previous generations BMW's and know some of the tricks of the trade.
IMO, and i hope someone can correct me, i dont' think octane plays a part in the fuel open loop. seems to me that it's directly related to the PSI increase. the higher octane increase the combustion but it's still the same amount of fuel. that is unless the mix of e85 with regular gas requires a different value int he fuel open loop to adjust due to different type of gas (e85 mix)
PS. this is my interpretation of this and by no means fact. i know enough to break sh*t.
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