[Carl Morris]

One thing that has bugged me about the fuel maps in general for the N54 is how they run 14.7:1 even at full boost at lower rpms. Maybe I'm just a neanderthal that wants everything to stay like it used to be, but I suspect that those choices are more about emissions and economy than performance. I don't know for sure, but I suspect that performance including spool would be better if the air/fuel ratio was more like what you would choose for max power.

So what I did was take my fuel maps and starting at the load column that was just less than 100 (which I assume is zero boost/zero vacuum, at least at sea level) and set all the cells in that column and to the right that are set leaner than 13:1 to about 13:1. I left all the other cells alone.

Driving it that way to work this morning I can feel the transition point because I didn't smooth the transition, but once I'm at WOT it feels to me like I'm getting boost a bit quicker and I don't get the annoying stumbles at low rpm and high boost that I think come from running boost at 14.7:1.

Still need to log, though, and see if it's doing what I think it's doing, or if I'm imagining it :-). Does anybody know if a load of 100 is different for different ambient pressures? In other words, does the load scale move in response to changes in barometric pressure? Or is it absolute? If it's absolute then WOT/zero boost might only be a load of about 80 for me here in Denver.

[Joshboody]

You need to log load and reference it to boost. Load is air mass, so it won’t translate to kpa which seems to be your assumption (unless it’s a coincidence). The DME works off absolutes, so load 100 is the same for everyone, but you may have to build boost compared to others with higher ambient pressures. The affect is more heat and reduced VE… the DME may have some VE compensations depending on baro.

I’m still waiting on my bro to return my AP so I can check this out ATR.

[Carl Morris]

I understand what you're saying. I was just curious if BMW did anything unusual like scaling the load values due to barometric pressure. I'll assume not. I was assuming that manifold pressure = atmospheric pressure would give me a load of about 100 at lower rpms...at least at sea level. That's usually been a safe assumption for me in the past.

[ZTUNER]

Originally Posted by Carl Morris

One thing that has bugged me about the fuel maps in general for the N54 is how they run 14.7:1 even at full boost at lower rpms. Maybe I'm just a neanderthal that wants everything to stay like it used to be, but I suspect that those choices are more about emissions and economy than performance. I don't know for sure, but I suspect that performance including spool would be better if the air/fuel ratio was more like what you would choose for max power.

So what I did was take my fuel maps and starting at the load column that was just less than 100 (which I assume is zero boost/zero vacuum, at least at sea level) and set all the cells in that column and to the right that are set leaner than 13:1 to about 13:1. I left all the other cells alone.

Driving it that way to work this morning I can feel the transition point because I didn't smooth the transition, but once I'm at WOT it feels to me like I'm getting boost a bit quicker and I don't get the annoying stumbles at low rpm and high boost that I think come from running boost at 14.7:1.

Still need to log, though, and see if it's doing what I think it's doing, or if I'm imagining it :-). Does anybody know if a load of 100 is different for different ambient pressures? In other words, does the load scale move in response to changes in barometric pressure? Or is it absolute? If it's absolute then WOT/zero boost might only be a load of about 80 for me here in Denver.

You will need to make adjustments in the fuel spool table IMO. Personally i would compare a few things between different cobb tunes to get a good idea of what is going on. I just got the cobb link about 10 min back and figured out a bunch of differences already. This is exciting stuff !!!

Harry

[Carl Morris]

I'm a little confused by the spool tables. What was BMW's goal when in that fuel mode? Was it to spool faster, or ??? When I look at the tables related to that mode it appears that they made retard timing a bit, which makes sense to me, but they also seem to lean it out, which makes no sense to me. Sure, you don't want to be pig rich, but I don't think you want to be that lean for quick spool either. And then they stop at about 3000rpm...why wouldn't you want it at higher rpms? I'd be curious to hear from anybody with a strong understanding of what BMW is trying to accomplish in that mode...

[rader1]

Originally Posted by Carl Morris

I'm a little confused by the spool tables. What was BMW's goal when in that fuel mode? Was it to spool faster, or ??? When I look at the tables related to that mode it appears that they made retard timing a bit, which makes sense to me, but they also seem to lean it out, which makes no sense to me. Sure, you don't want to be pig rich, but I don't think you want to be that lean for quick spool either. And then they stop at about 3000rpm...why wouldn't you want it at higher rpms? I'd be curious to hear from anybody with a strong understanding of what BMW is trying to accomplish in that mode...

This just a guess on my part but it sounds like spool mode may be for emissions. Remember, everything a manufacturer does is regulations(safety, emissions, fuel economy) first and performance a distant second.

[Lulz_M3]

My guess;

Lean fuel + timing retard = high EGT = faster turbo spool.

[Jake@MOTIV]

HARRY!!! (ZTUNER) Good to see you are still around. I was testing ATR for the last few months. You will be happy when you find the time to play and get some maps done.

OP- as they have said - its not that straight forward with values. Do two or three logs and remember what you did in each. Follow the requested/actual load trace and figure out what you want to do with the fueling. Especially at low load the AFR values this car runs are semi okay. Its actually surprisingly efficient. Now if you really think the turbos don't spool fast enough - log fuel mode to see what mode you are in to make sure you are adjusting the right table as you may not be without knowing what mode you are in.