MHD+ map switching and flex fuel

[langsbr]

I know this isn't necessarily "advanced" but I don't think the general forum would get much traction.

I'm redoing my current legacy flex fuel tune for MHD+ with map switching and also the ability to use the new boost control method. My main goal would be to continue to leverage flex fuel but have various maps with different boost levels, e,g, Map 1 - 12psi, map 2 - 18 psi, etc.

What has confused me is the Flex fuel vs the custom base tables boost control.

Map 2 - easy enough - MHD+ Suite\Map Switch - Slot 2\Boost Control\ Boost Ceiling (relative) (gear x rpm) (Map 2)

But for Map 1 - do I use:
Custom Base Tables (Map 1)\Boost Control\Boost Ceiling

or

FlexFuel\Boost Control\Boost Ceiling

It's not explicitly stated in the Tuning Guide, but my thought is to use the Flex Fuel boost ceiling and ignore the Custom Base Tables as that may be just for when wanting to use the new boost control but not with flex fuel. Is that correct?

Also, if I want the default flex fuel fueling and timing maps to be used in each map, I presume they need to be copied from the base flex fuel tables to the map slot tables as well, or will it use the base tables?

 

[langsbr]

Now I am wondering if I should have my 93 fueling and timing maps in the map 2 slot, and let flex fuel control the interpolation. That makes more sense.

 

[Jake@MHD]

Map 1 uses "Custom Base Tables (Map 1)\Boost Control\Boost Ceiling" if you have the 3D boost ceiling enabled.
The Flex Fuel table is blended against from whatever map slot's table you are in, specifically with the FF Load Ipol table for that map slot.

That said, you won't really have different boost targets this way unless you are on pump gas for each map slot, as you will be blending with the FF boost ceiling table.

If you want FF enabled in each map slot, are always running only 93 oct base, and want different boost levels per map for the same given E%, it takes a bit of creativity. It's best to set the tables up reversed. Where map 1 - 4 will be your E85 maps with various boost ceilings, and the FF tables will be your 93 base. You then set the ipol factors in reverse.

 

[langsbr]

Thanks Jake. It made more sense once I started to think about it so I set it up that way. E85 is rare around me, so I am running primarily 93. I think it would be nice to have multiple boost selections for 93 - low boost for wife, one that mimics an NA motor as far as torque delivery, and then the normal tune I'd drive around on 93 (not a kill tune or anything). Once I add some E, it can interpolate and give me all the boost and timing.

If I have the MHD Boost ceiling tables enabled - should I log only the new MHD+ values or continue to use the old?

I logged just the new ones but they are all reporting zero throughout a log.

 

[Jake@MHD]

I only recommend logging the new ones if you have scaled the tmap. I forget off hand, but I believe that is required for them to be populated.

 

[langsbr]

You mean the 3 cell map conversion for a 3.5bar map sensor? I do have that set.

 

[ddoublee]

@Jake@MHD Since we are limited to a single FF table on N54, would it ever be possible for us to have the option to limit ourselves to 3 map slots, and be able to alternatively use slot 4 as an FF2 table? I have no idea what this would take from a coding perspective, or if the DME could even handle the logic, but it would be nice if say we wanted a low boost map on slot 1, and have it interpolate with slot 4 as an FF2 table. Then slots 2 and 3 could be used for medium/high boost tunes and they could both interpolate with the standard FF1 table.

I'm sure there are reasons I don't understand for why this won't work, but either way, I am still amazed with the current feature set of MHD and the options it has brought to our platform.

 

[Jake@MHD]

@Jake@MHD Since we are limited to a single FF table on N54, would it ever be possible for us to have the option to limit ourselves to 3 map slots, and be able to alternatively use slot 4 as an FF2 table? I have no idea what this would take from a coding perspective, or if the DME could even handle the logic, but it would be nice if say we wanted a low boost map on slot 1, and have it interpolate with slot 4 as an FF2 table. Then slots 2 and 3 could be used for medium/high boost tunes and they could both interpolate with the standard FF1 table.

I'm sure there are reasons I don't understand for why this won't work, but either way, I am still amazed with the current feature set of MHD and the options it has brought to our platform.

If you want varying boost levels while having all map slots blend with FF, you can do this with a bit of creativity.

I suggest using the FF tables as your "91/93 pump" base, and then use each map slot as your varying power levels you would like while running E (or not). For using them as different power level FF map slots, you would simply set the interpolation tables in reverse. If you wanted to use one as a slightly higher powered pump gas map (and then blend higher w/ FF), you would just set the ipol at 0 or 10%E (whatever you pump gas content is) to already blend a small portion of the way to the map slot (load only) and leave fueling / timing etc in the FF tables (which you are using as the pump base here remember).