Ecumaster forum

Hi everyone,

As the first step in advanced fueling strategy and the new autotune option is setting up a Lambda/AFR target table, I thought it would be a good idea to share our tables together with info about the engine/mods so we can learn from each other and setup a base table which gives you a relative safe starting point.
Some info about AFR numbers with thanks to Clem:

clem wrote: AFR Target table should be tuned accordingly to VE and EGT. Higher VE means higher cylinder pressure and therefore higher combustion chamber Temperature. Higher gas temperatures in the compression stroke give a higher tendency to abnormal combustion (Knock in best case, Pre Ignition in worst case). To give you an idea:

Knock: Ignition happens beginnning with the spark and great amounts of gas burn immediately, therefore creating great amounts of heat -> melted pistons.
Knock happens tendencially in low engine speed and high load conditions. At higher RPMs (>5000) there is not enough time to develop a detonation.
can be avoided with: retarded Ignition angle, lower charge temperature, lower compression ratio, fewer hot rest-gases from last combustion, good homogenized charge, well designed combustion chamber without hotspots.

Pre-Ignition: Ignition happens in the compression stroke before the spark occurs, again much gas burns immediately. The damaging cause here is the extremely high cylinder pressure -> broken pistons/conrods, bent conrods. Pre ignition can be experienced in all engine speed ranges, at high loads. The pre igniting cylinder(s) would run in "diesel-mode" into self destruction within a hand full of cycles, if not the fuel injection is shut off after the first event.
can be avoided with: lower charge temperature, good homogenized charge, lower compression ratio, well designed combustion chamber without hotspots.

Only add fuel (lambda < 1) if there is danger of abnormal combustion or your EGT is too high for your turbo or your catalytic converter.
At lambda ~ 0,9 you could get the most power out of your charge. At lambda ~1,1 you could get the most power per fuel out of your charge.

With these very generic rules you should be able to create your own Target AFR table. VE, IGN, AFR, BOOST, have to be tuned to work together for one specific engine setup.
Compare Maps from different engines with different mods could mislead you if you do not 100% know what you are doing. Try to give your setup what it needs and have fun with that vastly big puzzle
Start at low engine speeds and loads, where you can hardly ruin a thing, to get a feeling for tuning an ECU.
Clem

For my first attempt I kept the numbers relative low to be on the safe side as no tuning has been done yet.



Download link .emut file
https://www.dropbox.com/s/a2nld2qxcgh50 ... .emut?dl=0

My engine:
VW 1.8L 8V
T28 turbo
550CC injectors
270 degree cam
Group fire injection, distributor for spark.

Updated the screenshot and download link.
For now the above table is working ok for me. The results from auto-tune gives me a very decent VE base-map.

Very curious about suggestions / tips and tables that others are running though

It is too rich in general.

Hi Nick, thanks for your input, it was indeed rich, specially in the lower rpm`s.

I did this as I used it as a base for startup and first drive and wanted to be on the safe side.
Now I know it`s ok, I leaned it out and will try from here.

Here`s the link to the slightly leaner map if anyone is interested:
https://www.dropbox.com/s/b0mfou6kvmtgm ... 10.emut?dl



What are your targets and how are they working for you?

Hi,

AFR Target table should be tuned accordingly to VE and EGT. Higher VE means higher cylinder pressure and therefore higher combustion chamber Temperature. Higher gas temperatures in the compression stroke give a higher tendency to abnormal combustion (Knock in best case, Pre Ignition in worst case). To give you an idea:

Knock: Ignition happens beginnning with the spark and great amounts of gas burn immediately, therefore creating great amounts of heat -> melted pistons.
Knock happens tendencially in low engine speed and high load conditions. At higher RPMs (>5000) there is not enough time to develop a detonation.
can be avoided with: retarded Ignition angle, lower charge temperature, lower compression ratio, fewer hot rest-gases from last combustion, good homogenized charge, well designed combustion chamber without hotspots.

Pre-Ignition: Ignition happens in the compression stroke before the spark occurs, again much gas burns immediately. The damaging cause here is the extremely high cylinder pressure -> broken pistons/conrods, bent conrods. Pre ignition can be experienced in all engine speed ranges, at high loads. The pre igniting cylinder(s) would run in "diesel-mode" into self destruction within a hand full of cycles, if not the fuel injection is shut off after the first event.
can be avoided with: lower charge temperature, good homogenized charge, lower compression ratio, well designed combustion chamber without hotspots.

Only add fuel (lambda < 1) if there is danger of abnormal combustion or your EGT is too high for your turbo or your catalytic converter.
At lambda ~ 0,9 you could get the most power out of your charge. At lambda ~1,1 you could get the most power per fuel out of your charge.

With these very generic rules you should be able to create your own Target AFR table. VE, IGN, AFR, BOOST, have to be tuned to work together for one specific engine setup.
Compare Maps from different engines with different mods could mislead you if you do not 100% know what you are doing. Try to give your setup what it needs and have fun with that vastly big puzzle
Start at low engine speeds and loads, where you can hardly ruin a thing, to get a feeling for tuning an ECU.

Clem

nickbmw wrote:It is too rich in general.

Do you think that its too rich also at high rpm/boost? Inmo, (I'm not an expert) for turbo engines, 0,82 at 5000rpm and 200kpa isn't too rich, for me its correct, even many turbo engines need more fuel or depending of mods. In my gen 3 3sgte, 0,79/0,80 its a really nice value for this conditions

Hi Clem,

You`re absolutely right that one doesn't suit all and that every engine needs it`s own tailored tune. My intention was only to create a thread which contains basic knowledge about setting up a safe starting point as this isn't part of the manual.
I copied your text to the first post as there is some good basic info in there, hope you don`t mind

@Pepifebles, I agree with you at the around 0.78 to 0.81 at 5000RPM 200kpa. For most applications these are safe numbers with plenty of power. It was specially the low rpm / cruise part that needed to be leaned out a little.

This is mine.
3 gen 3sgte
Turbotechnics s148-3 hybrid turbo
Sard 800cc High Z
3" exhaust
HKS intake filter

A few days, I try this fuel map. I saw one like that in ATS post. I think that its best way to my 3sgte, really we do all the range of cells and use just a few that are given in our particular conditions


[IMG]http://i64.tinypic.com/259io0y.jpg[/IMG]

Hi,
this is mine. Set up how I learned it from a book about tuning without caring too much about fuel efficiency, just give it enough cooling.
Engine is a Nissan SR20DET, bored, forged, CR 9:1, high reving and with a good amount of boost