Calculating slope of map vs aircharge and map at 0 aircharge

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Calculating slope of map vs aircharge and map at 0 aircharge

Unread postby fernando_221 » Fri Jun 26, 2015 1:43 pm

Hello all,

This is my first message here and I'll be glad if you help me.

I have a turbocharged Ford Focus (EEC V ecu), it's speed density based (no maf, just map sensor). The ecu is tuned with SCT Advantage III and the current tune I'm running is great, it's from MDS (http://www.tudyno.com/). But I would like to tune it my self, I have read Greg Banish's books and started a new tune but I'm having trouble trying to understand the fuel tuning, the tables slope of map vs aircharge and map at zero aircharge (in fact these are ramps, not tables).

Engine is a Duratec 2.0L, Siemens 60lb injectors and a Bosch 2.5 bar map sensor (stock one is 1.15bar I think).
I started the tune by changing the base fuel table, setting injector values and the map area slope of map vs aircharge and map at zero airacharge tables I divided the values by 2.5/1.15 = 2.17 (the value of new map sensor divided by stock map sensor). The car runs good at low rpms and idles fine, but I would like to understand how to tune these 2 tables.

I don't know if I made myself understand, please let me know.

Thank you
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Re: Calculating slope of map vs aircharge and map at 0 airch

Unread postby decipha » Fri Jun 26, 2015 4:05 pm

yep you've made yourself perfectly understandable

I've never seen any ford documentation on the MAP slope functioning or tuning, however, the MAP slope doesn't have any correlation to the MAP sensor itself, its used in the Accel Enrichment calculation routine with MAF setups, supposedly its a model of the actual MAP slope based on the engines VE, it doesn't usually require adjustment

reducing its value will give you more accel fuel

here's a tid bit i wrote up a few years back on my understand of transients, not all of this will pertain to your strategy

dyn_min_arc is the minimum airmass required to enable dynamic make up fuel, i set this to 0 in all calibrations

TFC_MIN, transient fuel must exceed this threshold to be added to the fuel calculation this scalar is bypassed for decel, i always set this to 0, the other idle transient switches will prevent transient fuel from causing idle surge

decel tip out fuel is multiplied by AIR_DEC_MUL, its a multiplier on manifold volume, typically ends up around 1.10 % or so

MTEFTC is the transient constant multiplier, it multiplies the constant tables the fn1322's

tfc_multa and tfc_multd are direct multiplier on transient fuel

all 3 of the fn313 functions multiply transient fuel, i always set these functions to all 1s

some of those weren't available until 98+, if your def doesn't have these available then don't worry its not a biggie you can still dial in transients pretty good without them

FN052N is the MAP AM slope, increase map slope where engine has became more efficient, however, at peak tq slope will be lowest, remember typically when you increase hp on the big end you loose tq on the bottom end

FN052M is the MAP RPM slope, MAP at max engine efficiency (0 vaccum and 0 boost), used for transient slopes, MAP at peak tq (RPM where engine is most efficient) will be significantly LESS than when the engine is out of its power band, the MAP slope is typically not effected below peak tq on a boosted engine, when boost is added the slope usually increases LINEARLY from just above the peak tq rpm to approx, 1.5x at 5250 rpm

fn1321 is the transient fuel table, its the same transient fuel table henry has been using since the 80s, its even in the gufb strat, increase/decrease the cells for lean/rich spikes on transients using AFR/lambse ratio (just like dialing in the maf) at least thats how i do it and it usually works out about right, if lean/rich spikes occur after the transient then increase/decrease the constant tables (the fn1322's)

fn1322al is the time in seconds that acceleration transient fuel remains active, typically you would reduce the cells that cause the hegos to over-enlean on transients due to transient fuel staying in too long, boosted engines typically want approx half the time for transient enrichment to remain active as they do when not in boost thats just what i typically find works out best

fn1322dl is the decel time constant that transient fuel remains active, typically on modified engines the lower loads during decel when at warm engine temp fuel needs to be removed for a longer period of time, 4 seconds isn't too uncommon at least in my experiences

fn1323a is the transient fuel global multiplier for TEISF (transient fuel) during acceleration, typically after 90 seconds most engines will want about half the transient fuel they want with the excess friction from startup, remember for every closed throttle low load decel condition, an accel condition is recognized when load comes back up as the rpm's near idle and the engine restabilizes, this is why it is important to dial in DASHPOT so transients aren't always compensating when they don't need to be

fn1323d is same as above except for decels, (closed throttle and tip out), IMO, this table is practically unneccessary, I always keep each column uniform regardless of time, typically additional friction from startup has very little effect on transient decel fuel requirements in my experiences
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Re: Calculating slope of map vs aircharge and map at 0 airch

Unread postby fernando_221 » Mon Aug 31, 2015 1:28 pm

Hello decipha,

Do you have an email where I can send you some screens of my strategy in sct?

Thanks
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Joined: Wed Jun 24, 2015 4:19 pm
Name: Fernando
Vehicle Information: Ford Focus Turbocharged tuned with SCT Advantage III, WNCDAQ4 strategy

Re: Calculating slope of map vs aircharge and map at 0 airch

Unread postby decipha » Mon Aug 31, 2015 2:13 pm

post them here
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decipha
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Posts: 15709
Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce


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