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e85 afr

Understanding AFR

Discussion and questions related to the course Understand AFR


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Hi, i was wondering, if i run example 2bar of boost, in full and have around 15-18deg ignition, and on VE table 105-110, do i need to follow my Stoichiometric AFR of 9,8? or i can go lower, on 8 example (to get rich mixture)

What ECU are you tuning with? Does it have some kind of compensation for the stoichiometric AFR of the fuel, or flex fuel compensation?

In theory the volumetric efficiency tells the ECU how much air is entering the engine, and you would not change the base VE to account for E85. You would have some other compensation to account for the cooling effect of the fuel, and the different stoichiometric ratio. And then you would have an actual target Lambda table. However it is highly dependent on the application (Engine & ECU). Some ECUs account for all the varying effects of E85 and in some you just have to bake it all into the tune (skew the VE table, change the injector size setting, change the pulsewidth map or some boost compensation, whatever)

im using EMU ecu master, and engine is 2.8. vr6 from vw, swaped to turbo, its running on 2000cc injectors, gtx35 turbo, big IC, stealed rods, cams is sport, etc etc, also i have option to tune with afr or lambda map

lambda and VE

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I'm still trying to understand your question. I see the screenshots you posted. The target lambda table you made is not fully optimized, but it's a good enough starting point. Now you need to adjust other parameters such as VE table to achieve the target lambda.

thats what i want to hear, so i need now to work on VE, to get close to this target, its lean in full load, what do you suggest to me, just give me some orientation, with this something about 520-530ps car have on dyno, but problem is, i dont have access to dyno in my area :( need to go in another city and measure car, and its just drag racing car

I don't know the details of Ecu Master EMU, but the first step would be to adjust the VE table. I assume you are running open loop under boost (no wideband adjusting fuel).

Ok, thank you, yes im using open loop

I'd suggest that you may benefit from going through our Practical Standalone Tunign course and watch some of the worked examples on VE-based ECUs. We don't have an example on the ECU Master right now but the tuning fundamentals of a VE based ECU are the same. There's an example on the Link G4+, AEM Infinity, Haltech Elite and Motec M1 which all use VE based tuning. If you don't approach the tuning correctly then you'll end up with a bit of a mess.

I would like to see some tuning with high boost, example 2bar, to see how its someone else done, also in your course you base course to atmo engines :D but its usefull everything, also if you have some video with high boost, i want to see that. im gooing trough worked examples module, steady stake is best but if dont have dyno is little hard...