A few questions. M20b25 173DME

Discuss Bosch (Porsche, BMW, Volvo, etc) tuning topics here. Request definitions, discuss parameters, etc.

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Daeldalus
Posts: 3
Joined: Tue Oct 21, 2014 1:51 pm

A few questions. M20b25 173DME

Post by Daeldalus »

first off; I do not yet have any tuning hardware for my car and am testing tuning on a free bin and free version of tunerpro.

on the fuel maps; what are the other axis variables? one side is labeled
rpm and is self explainitory but the other side has no value. also, the values
themselves inside the grid have no description what do they represent?
injector pulse width? those values go from 0(lowest) to 255(highest) correct?


on this DME fueling is also heavily influenced by AFM right? does the rpm
map take precidence over the afm map for fuel? both have to work
together for things to work well? grid values in these maps mean the same thing?

fuel tuning in this case would consist of using a wideband to see what afrs
are and then trying to keep them within a safe range? what is a safe range?
safe ranges different from NA to FI?

timing advance maps are fairly ok to understand what they are but what
are the goals for tuning them? as much advance as does not detonate?
fuel or timing more important to tuning?

also i see that in most of the rpm based maps for the stock chip that both
timing advance and fuel go up and down by considerable amounts. in the
ign wot map you see 30 advance at 3000 but goes down to 15 by 5000
why? would such things( fuel especially) not go up steadily with rpm?


any tips or specific tunes for this so that i can see what others have done
successfully would help........ thanks in advance
Daeldalus
Posts: 3
Joined: Tue Oct 21, 2014 1:51 pm

Post by Daeldalus »

does not a single person know the answers to any of these questions?

I am not in a rush to figure all this out but I would like to have some info
to go on. I have not seen the answers anywhere on here and afm systems
seem to be different than other systems to tune.

please take the time to help me out here.
Last edited by Daeldalus on Sun Oct 26, 2014 1:36 pm, edited 1 time in total.
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biela
Posts: 33
Joined: Tue Jul 22, 2014 1:01 pm

Post by biela »

On the fuel maps the axis are rpm and load. Inside the map there are trim values applied to the fuel.
A safe range in NA could be 12.5 AFR, richer in FI to avoid detonation.
Timing needs varies with load.
Daeldalus
Posts: 3
Joined: Tue Oct 21, 2014 1:51 pm

Post by Daeldalus »

thank you this will help me a good deal to understand what is going
on with all this

you happen to know how the load is calculated?
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