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Target AFR rich on low load

EFI Tuning Fundamentals

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Hello,

I'm running ft86 platform, NA, self tuned Ecutek. I'm having trouble with cruise(around 2-2.2k RPM) - namely CL & loads under 0.3(off chart) ECU targets AFR 13.7

Does anyone know or can hint where to look for a problem?

trims are fine(~1%), MAF is scaled(more or less).

i would rather not go with a path of rescaling fueling to have 0.2 load described. but i'd guess it's better than messing with injector pulse width.

my fueling table orders 14.6-14.7 in range of 800-3200RPM and 0,3-0,6g/rev

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any ideas? anyone?

I am not clear as to what your problem is. If the trims are fine, then is the commanded AFR not what you want or expect?

Exactly. I would expect ECU to interpolate the fueling table when it goes out of bounds(in this case load < 0.3, which is last point described in fueling table).

The commanded AFR is not indeed to my expectations, i would assume 14.7, but ECU commands for 13.7.

This is not a big PROBLEM per se. but i'm failing to understand why doesn't ECU continiue with target AFR 14.7, which is demanded by fueling table in closest cells to running conditions(cruise, low throttle input, RPM ~2k and load 0.24 to 0.29).

This scenario does create a problem a bit with exhaust tuning and also ignition advance, because my fuel mix changes approx 7% with this change of load from 0.29 to 0.3 and also with tip in enrichments. When i accelerate from this point, AFR goes lean first(to 14,7 as it reaches according cells, then pumps up a bit to maybe 15.3 untils coming back rich as would be expected with well made tune).

Why i'm asking this here, is that maybe i'm having completely wrong approach to this and i should look at it from some completely other angle, that i cannot think of - because i'm with very little experience. til now, i dont think "cleaning air filter" or any other mechanical change would benefit in any other way, as throttle will be as much closed as it was before and crankcase ventilation as much open as now - so this action should give little to no result.

So my misunderstanding comes from the point where i'm getting 13.7 commanded AFR on super low loads and cruise conditions. i do think this generates enough confusion in me and ECU to have it corrected =)

I understand that Ecutek may not reveal every table in the ECU. Perhaps there is a target AFR table that is what you really need to address. Or perhaps the richer AFR is needed to prevent some drivability problem (i.e. perhaps surging?).

It seems like a reasonable test would be to lower the minimum load load breakpoint and see if that allowed you to control the AFR better. Why are you reluctant to give that a try?

i'm not too reluctant, but rather novice in this. so i do approach with caution to any action. mhh, indeed, this is a very good idea. i first thought rescaling fueling would not be too fancy because of losing range and precision in AFR target/fueling map. but i could easily lower the first column load value and ECU would fill the rest between skipped load values.

Heh, great thanks for support and ideas. i will definetly try this out. i'll return with either great success feedback or additional problems xD

For now, thanks again =)