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Hi,There's a user changeable flag which can dedicate the two main fuel to act as cold/warm main fuel tables. As, however, a multi-cylinder engine always requires different fuel values for each cylinder this arrangement would only make sense on a single cylinder engine. As it turns out the code base used in the MIUG3 is very similar to the MBC1 ECU used in a number of BMWs. Some of which, I believe, are single cylinder engines.CheersMeinolf
It’s interesting that the MIUG3 can be configured different ways. Can you clarify if, as used on our V7/9’s, the warm and cold tables are in fact configured as left and right? Thanks.
Changing any of the trim and scaling scalars or tables generally not a good idea. In the past I've found that Marelli uses airtemp/pressure correction values in the respective tables of the 15M/RC and 5AM which are wrong. They differ from the values dictated by the general gas equation pV=mRT, I created a spreadsheet several years ago to calculate the correct values and used this in my BINs.CheersMeinolf
There is one table for Idle at 0x7D77A, how is the right and left distribution adjusted?
Is this along the lines of what you found or am I way off base?
Is it significant enough to change?
Hi Chris,the idle fuel calc uses, same as main fuel, two tables. The one at 0x7D77A is for the left cylinder, the values for the right cylinder are calculated using a delta table at /D97A and adding/subtracting these values.mov r12, r8 ; IdleFuel value leftmov r13, r4 ; IdleFuel delta value rightcalls 0C3h, add_unsigned_R12_R1 3_sub_C30014 ; here the 2 values are added, or subtracted in case the delta value is negativemov r8, r4 ; IdleFuel value rightCheersMeinolf
... and using the 1976 Standard Atmosphere Calculations I came up with slightly different values.
Here is what I get with values from my Roamer and adjusting labels for the differences of temperature and pressure points with the MIUG3. It looks like a lot of areas would run richer using those calculations. I'm curious about your using 990mb @ 20C (green) as a base. Is that a Guzzi thing?
Is that a Guzzi thing? I would have expected to see 1013mb (sea level) @ 15C which is the standard for calculations I'm familiar with.
Here is what I get with values from my Roamer and adjusting labels for the differences of temperature and pressure points with the MIUG3. It looks like a lot of areas would run richer using those calculations. I'm curious about your using 990mb @ 20C (green) as a base. Is that a Guzzi thing? I would have expected to see 1013mb (sea level) @ 15C which is the standard for calculations I'm familiar with. I'm still learning, though.
What else is a factor here?
Thanks, Chrisfer. I hadn’t considered that engine heat would affect the sensor at the MIUG3. Should have.
More MIUG3 curiosities for the sake of discussion. I charted the percentage differences between my V9 right and left fuel maps. I realize that slight differences in manifold length from the "y" as well as small surface differences affecting flow as well as valves and seats, even flow into the cylinder and piston position will affect flow. I would have expected much less variation than the results show. Like maybe one side is very slightly less efficient or has slightly more impedance to air flow. The chart shows highly chaotic differences and at some points more than 25% differences. How can this be? Is it due to turbulence at different throttle openings and RPMs? What else is a factor here?
Let's look at the main fuel tables first. Right at the top a branch conditions selects if idle or main fuel tables are required, which is the TPS state. If it's open, the next conditional branch is Engtemp_above_thres hold_flag_8AFD. The flag is determined elsewhere, but basically it's One if the engine temperature exceeds a threshold value and Zero if not. If the threshold (60°C in this BIN) is exceeded, then the Ign_Adv_Main2_Table _C79014 is used as base for the following calcs. If not, then Ign_Adv_Main1_Table _C78B14 is used.
Anyway, in light of your observation the conclusion is obvious. The main fuel table at (C)79014 is a limp-home table used if the engine temperature sensor is defective.CheersMeinolf
I wonder if the 2021’s are using a redesigned unit.