LMM Lambda and Boost

[monster50iii]

I've never had pids work to view air per cylinder, I've tried many updates, but it has never worked for me. But it seems that the b0795 table's amount of air on the left hand side gets surpassed by boost somewhat easy. Like 10-12psi easy. I might be wrong tho. I noticed this when making my table progressive that I wasnt able to limit smoke very effectively at higher boost with b0795 like I could below 5psi. I'd be curious to know if what you think is going on between elevations and b0795 is accurate

 

[2004LB7]

B0795 seems to work on mine along with the appropriate pid but like you said it gets surpassed in the higher boost areas. But I've only logged this at low elevation. I have no data to tell me where it operates at in high altitude. I am certainly not making the same boost at high altitude as I am down low

My tune maxes out at 27 psi on the high altitude boost map.

I imagine the pid is just a simple formula that make that pid work. BARO, MAF and RPM are probably all it needs to calculate air per cylinder. If I knew what the formula was I could probably work backwards to get a good idea where I need to make the adjustments

 

[monster50iii]

So for me in my area my baro is 97kpa.

I make whatever changes to my low altitude boost table, copy and paste it to medium altitude boost table, and subtract 12kpa from it. I do the same for high altitude, but I then subtract 37kpa from the entire table. I believe that is the correct way to setup boost tables to be the same from low altitude to high?

 

[Bdirtymax]

I would still be in the same boat but with a different set of tables. Not having any logs showing where it operates when at high altitude limits what I can do.

That is the idea in theory but the ecm does it calculations from the information in the tables. So if the tables says to pull x amount of fuel at x altitude it will do it regardless of what it says for low altitude. The issue is we dont have a separate B0795 table for different altitudes so we need to make one table wotk for all.

As I sit right now, it runs really well at low altitude with very little smoke. But somewhere else in the table it is telling the ecm to only allow x amount when I'm at higher elevation. This is the part of the table I'm struggling with. Without any logs I don't know where it is. If I lower the wrong area or the whole table to inject more fuel then I would have to rework a bunch of tables to fix spool and smoke at it may still limit fuel at elevation. I would rather, if possible, just tweak the one table

I'm sure you've looked but torque based fuel cuts a lot of flow in the high alt table compared to low alt. The calc.cylair pid works for me. I have several logs with it on my LMM but I'm low alt.

 

[2004LB7]

So for me in my area my baro is 97kpa.

I make whatever changes to my low altitude boost table, copy and paste it to medium altitude boost table, and subtract 12kpa from it. I do the same for high altitude, but I then subtract 37kpa from the entire table. I believe that is the correct way to setup boost tables to be the same from low altitude to high?

I use compression ratio of 3.2 for my boost maps. Im sure there is room for improvement but seems like was building boost ok. But without logging it I don't know for sure

 

[2004LB7]

I'm sure you've looked but torque based fuel cuts a lot of flow in the high alt table compared to low alt. The calc.cylair pid works for me. I have several logs with it on my LMM but I'm low alt.

Yeah, I figured that one out a while ago. My calcair.pid didn't work at first but got it working now. But I'm stuck down at low altitude for a while so no logs

 

[2004LB7]

ran a low altitude log of the cylinder air at low altitude just to see what I get

attached shows where it ran. green is the idle area, orange is normal running and cruising & blue is when I was applying heaver throttle. light gray areas, never even ran into it. maybe at higher altitudes????

 

[2004LB7]

correction, this is the right values I have in the table

 

[kidturbo]

Limits the amount of fuel injected to what the ecm thinks is a particular are/fuel ratio

And/Or

Tells the ecm how much air it need for a given amount of fuel

With this table enabled, the ecm is running what seems to be much higher average boost then with it disabled and it running off of the boost and vane tables. This is what makes me think it is controlling boost to make the air/fuel ratio match the table

Wished I'd have found this thread last week... Would have save myself about 10hrs. Did find the thread relating to LBZ and LMM using opposite values in B0795 and related.

Luckily Mark recalled this being a possible fuel limiter. In a speed density setup, this really comes in handy. I was having issue at 1700-2200r no spool loaded due to slight lack of fueling. By lowering the values within that range 15%, the Main mm3 increased from 60mm3 to 75mm3 in that area. Enough to light the turbo, and and deter any nearby misquotes.

As stated by EFIlive, table B0797 appears to be useless in the LMM. I lowered the value, no change. B7095 is always active, and limiting fueling based off of boost pressure in speed density for certain. It wants to see a MAP2 value of 16-20kpa above baro while below 2000r before it will follow the actual fueling table value.

 

[2004LB7]

Bumping this back up to see if I can get more information and help on high altitude tuning

As many of you know, I drove to Nevada to pick up another truck and tow it back. When I was going over the pass as around 7k feet and a few other places in NV that where around 6500 feet my LMM basically fell on it face with power. So much so that it had a hard time maintaining speed even unloaded.

I brought my laptop and V2 with me to look at all the values and see if I could adjust the tune to make it run better. But for the life of me I couldn't get it to fuel harder. It seemed to be limiting somewhere around the mid 40s mm3 to low 50 mm3. It wasn't a hard stop on the mm3 so I don't think it was hitting a limiter or limp.

Boost was also only in single digits. Usually around 4 or so PSI even when under a load. Weirdly the commanded boost was similar. The command and actual vane was around 10%. This is perplexing because I could find no pard of my tune tables that should make it behave this way. It's almost like it was reacting to a MAF limit or BARO limit and reducing the fuel to match. But why wasn't it trying to achieve more boost?

I tried alternating the fuel mixture limit from the minimum to the maximum with little change in fueling. The best result I got was to add a tone of fuel in the BARO compensation table. But it still only got me mid 50 mm3. And no increase in boost

I went over all the tables multiple times looking for something that would prevent it from getting more fuel and commanding more boost but couldn't find any. I probably lost an hour or two from pulling over multiple times to make adjustments. Eventually I gave up and dropped the stock tune in it for the way back over the pass. Logs on the stock tune where going as high as 90 mm3 and 20 psi of boost and was just strong enough to maintain 70 at 7k+ feet elevation. It did have to downshift a lot and run at 2500 -3000 rpms but would do it unlike my custom tune which would have struggled to do 35 mph on the same grade pulling the same weight

Being that I'm back down to lower elevation it will be hard to do more testing to see what was going on. Also, I couldn't get the gms/cylinder or any of the air mixture PIDs to work. They all showed static numbers that wouldn't change.

Anyone else experience similar issues and figured out how to fix it?

Only thing I can think of to do next is to revert all the tables back to stock and add one table at a time from my custom one until it does the same thing. Then I can at least know what table is killing the fuel and boost

 

[JoshH]

I would be happy to take a look at your tune file and see if I can find anything obvious for you. tng josh at outlook dot com is my email (without any spaces or special characters other than the legit @ and . in place of the words I typed as a weak attempt at obfuscating my email address from any potential spammers).

 

[Stroked06Goat]

Glad i found this thread its a good read!