Hi Guys,
Working on my maps this week end, I finally understood why my timing maps are so different than my logs...
Logging with MUT2byte is actually perfect for fuel maps (I have lean spool disable), the intersection between 2bLoad and RPM exactly match my map but it was always different with timing until i tried to insert a new column in my Logs where the formula is:
Compensated 2bLoad = 2b Load x (baro/100)
Example: (@4500RPM) : 283 x (75.46 / 100) = 213.88 comp Load.
On my logs I have 8 degrees @ 4500RPM like my map @ 215 Load when I have 1 degree @ 280 load on my map...
Since I live @ 7000 ft high, it is a very big impact on my maps...
I hope my explanation to be clear!!!
It definitively change my life to know that there are 2 different interpretations of Load for timing and fuel maps!!!
I hope this could help other to tune their car on altitude...
Cheers,
C>

 

Mrfred posted this info a while ago:

Timing maps use baro+temp compensated below 77F. Above 77F, just baro compensated is used.

Fuel maps should be using baro+temp compensated essentially all the time. Below about 20 load in closed loop, uncompensated load is used for fuel.

 

Is this also for the Tepha roms? I asked Tephra about it an said he could not remember and that the difference was small...

 

From what I remember, this is all Evo Roms. For most people at standard elevation and temperatures, the loads will be similar. They will diverge as you approach extremes of elevation and/or temperature.

 

On my 5.1 Tephra ROM, Timing maps are baro compensated but Fuel maps are not.
May be that's why it was so important for me to find this out!
Cheers,
C>

 

Fuel should almost always be baro+temp compensated. Only very low load levels are uncompensated, based on what mrfred found from disassembly. Maybe something is different in your ROM?

As long as you verified how your ROM works, then you should be set, but just be 100% sure. It seems like you have verified through several logs, though, so it looks like you are on the right track.

 

At 4500', the difference is prett substiantial. A fuel load of 260 is a timing load of ~220.

I could be wrong, but I beleive tephra didn't change the load used.

 

Probably even moreso for Vigman, depending on where in Mexico. I think Mexico City (from what I remember when I visited), is about 7000 ft or so. (just looked it up..average elevation is 7349).

 

I will publish some logs this week just for you to know how it is around here with a baro under 0.8 !
Cheers,
C>

 

I'm confused. I used map tracer today to do a few logs and my timing vs map was not spot on. I'm using Tephra v5.10. Do I need to edit the program to get accurate results. I'm searching other threads but not 100% I understand. Its 110F outside right now so if I'm reading this right I need to log based on just baro compensated? Where do I make this adjustment?

 

It only makes a big difference if you live in high place over sea level.
I personally make the adjustment in Excel when I analyze my logs.
You have to log your BARO value and multiply your Load x Baro/100.
Cheers,
C>

 

I'm working on this but the timing in my map vs the timing in my log are WAY off. I did the math like instructed but these numbers still do not match up. What am I doing wrong? I'm going to keep trying to figure this out.

 

I have been having a similar issue. Elevation here is about 5800 feet. At wot the timing in my logs match my map but at 30% throttle in the 60 - 140 load area the timing is way off, how do I compensate for this?

 

For example, in your Log @4500 RPM you have:
2bytesLoad is: 293.75
Timing is:7
Baro is: 75.46 (set evoscan in metric unit)
To check your "real" timing map, do not read the timing value @ Load = 293.75 but instead:
293.75 x 75.46 / 100 = 221.66
You will probably see a higher value on your map, similar to Log...
I publish a sample log with example HERE.
Hope it helps,
Cheers,
C>

 

I understand what you are saying now. Thank you for the help. It is greatly appreciated.