Memory dump of ECU

[Calum]

Originally Posted by b3lha

OK. You're probably right.
I got the formula by looking at calculations that the ECUedit guys were using to decode the fuel map on Imprezas with the next-generation of JECS ECUs.

It looks pretty dang similar to the Nissan (also JECS) ecus. On the older models (same era as SVX) when you translate the table from a multiplier to a target AFR value it ends up at under load not matching reality. Its not really important, you just tune for reality anyways and the fuel map is just numbers you adjust until the car is performing how you want it, but it saves getting the same question asked over and over again on down the road.

I would make the table just x/128 or whatever and show that as a base injection time multiplier.

Unless it does end up corresponding to reality, in which case the above is a load of hooey. Get a wideband (plug: go with an Innovate unit).

[mbtoloczko]

Originally Posted by b3lha

I've discovered how to calculate the Air:Fuel ratio from the numbers in the Fuel Map. The formula is 14.7/(x/128)....

That's the same formula used for the Evo programming. (Probably a fairly universal formula.) On the Evo, the actual afr can be as much as 1.5 points off from the afr on the map. The actual afr does follow the trend of the afr map though.

[b3lha]

I think I see what you're saying: The values in the table are the target Air:Fuel ratio that the ECU is trying to achieve, but because no two engines are exactly the same, especially after 100k miles, the actual ratio of the fuel and air that ends up in the cylinder may not quite match the target. So you measure the actual ratio with a wideband sensor and adjust the values in the map to compensate for the engine's imperfections? Did I get that right?

I find it interesting that applying the formula has flipped the graph upside down. In the raw data, 80 hex is 14.7 (assuming the engine follows the target AFR perfectly). Values higher than 80 indicate more fuel, rich mixture, lower AFR. Values lower than 80 indicate less fuel, lean mixture, higher AFR.

[longassname]

128 is 14.7 without vacuum or pressure applied to the fpr

[b3lha]

Originally Posted by longassname

128 is 14.7 without vacuum or pressure applied to the fpr

Wow! Advice from THE guru!

Thank's for helping.

[TomsSVX]

Originally Posted by longassname

128 is 14.7 without vacuum or pressure applied to the fpr

Also, as far as I know the stock fuel pressure is 36psi w/o vaccum which should also be a good thing to know.

Tom

[b3lha]

I've now got the maps from a UK model ECU. They are similar to the USA version, but richer mixture at higher load and rpm, more knock correction and slight timing differences.

Details and pretty graphs on attached spreadsheet. To make comparisons easier, there is now a front page with all the graphs arranged with RPM on the X axis and Load on the Y.



One interesting thing for me is that here in the UK, we have both JDM and UK model SVXes driving around using very different maps. There must surely be some performance difference between them.

[TomsSVX]

i may have another set for ya soon

Tom

[b3lha]

Originally Posted by TomsSVX

i may have another set for ya soon

Tom

I thought you were running one of LAN's upgrades in your car? If so, please don't post them here without his permission.

Or are you saying that you've made your own custom map and you're willing to share it?

[TomsSVX]

No, I am going to dump the factory ROM for you from the upgraded USDM ECU's. I will not share the ecutune software as it is uner Mike's copywrite and I know better If I do tune the car to run better, I will share my finding with LAN from ECUtune so he may take my changes into consideration for his customers if he thinks they are proper. I am not entering the market for rewriting ECU roms, I am working for myself and the end result may be that stage 3 owners could be running better

Tom

[SVXRide]

Originally Posted by TomsSVX

I will not share the ecutune software as it is under Mike's copyright and I know better If I do tune the car to run better, I will share my finding with LAN from ECUtune so he may take my changes into consideration for his customers if he thinks they are proper. I am not entering the market for rewriting ECU roms, I am working for myself and the end result may be that stage 3 owners could be running better

Tom

Which is as it should be. LAN has done a tremendous amount of work (and invested his own $) to get us to this point and we are legally bound (copyright) to respect that.
-Bill (yeah, a law degree was a serious option before going with engineering)

[b3lha]

Originally Posted by SVXRide

Which is as it should be. LAN has done a tremendous amount of work (and invested his own $) to get us to this point and we are legally bound (copyright) to respect that.
-Bill (yeah, a law degree was a serious option before going with engineering)

I agree with you entirely, except on one small point:

The copyright on the ROM belongs to Subaru not LAN. You can't take a book, change a couple of pages and claim copyright over it. I think technically both LAN and I are breaking Subaru's copyright by distributing their ROM, but I don't think they would care too much.

Just to nitpick a little: I know some Americans seem to believe that everybody in the world should follow American laws, but the internet is a global medium, and laws differ across the world. You should not assume that everyone reading this is bound by the same laws as you. However, such discussion belongs in the political forum. I don't want to hijack this thread.

Anyway, I can't speak for the other contributors to this thread, but the work I am doing is not intended to compete with LAN. I do not have the tuning expertise to produce a B3lha-stage-1. Anyone who want's off the shelf performance chips should go to LAN. He deserves to get back the money he's invested. I'm just hoping to shed enough light on how the ECU works to make it easier for people who want to have a go at tuning it themselves.

[svxistentialist]

What Phil says is true as I see it.

Where the internet plays a part in the legalities it becomes a link that simultaneously makes the information public in a number of jurisdictions.

In that sense you could be challenged for copyright infringement in several different countries at the one time, just for "publishing" information on here

However, such challenges cost money, and Subaru would only issue a challenge or a warning if what you were doing constituted a threat to their earnings, and probably they would need to be sure you had enough money worth chasing.

People like us who love Subaru cars, and who are tuning their pride and joy, it would surely be like taking your kids to court for raiding the cookie jar.

Joe

[b3lha]

Originally Posted by svxistentialist

In that sense you could be challenged for copyright infringement in several different countries at the one time, just for "publishing" information on here

No. That is the whole point. A person can only be challenged for breaking the laws of the country they live in. Do we really have to discuss this in a Technical thread?

[Dessertrunner]

When I got a ECUstage 1 from Lan he said that the Aus SVX had a different pressure sensor (i think it was) at that his chip would not work in our unit. I have a reader on the way so when I get the info from my unit we will find out what the map is like. I would suggest that the differences in the maps between different models is related to things like air tempreture, allatude and fuel Octain aviability. The possiable differences in performance is most likly not much between all the models.
One question I have is do we all understand what each map does and how the ECU makes each decision as to what map info to use. Here is a couple of questions as to what I mean,
How is "Load" determined?
Is the fuel injection on timing only basied on Air/Fuel or is that only during crusie?

The reason I ask this is that we need to be clear about how each map and sensor fit together to understand how to change things.
Tony