2-bar / 3-bar hacking

They go by many names, P01, P59, VPW, '0411 etc . Circa 1999 to 2006. All VPW OBD2 PCMs.
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Re: 2-bar / 3-bar hacking

Postby Holden202T » Mon Apr 01, 2019 9:18 am

yeah the other thing to keep in mind with less resolution in the tables is, with a boosted motor you move through the tables faster so its not so much an issue of having less res.

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Re: 2-bar / 3-bar hacking

Postby ShorTuning » Mon Apr 08, 2019 10:44 am

NSFW wrote:I don't think there's much need to change the sizes of the tables... some resolution will be lost when the top of the axis changes from 1.2 to 4.5 or whatever, but I think we'll still have plenty of resolution with the existing tables. My Subaru's tables are considerably smaller and it does fine with 20-25psi of boost.

The load axis is the biggest thing, for sure.

I also really want to revise the way fueling is done. Not because it's strictly necessary but just because the concept of "power enrichment" seems like a hack (and "boost enrichment" even more so). I want a fuel table that has the same axes as the timing table - RPM and load. And add a simple compensation table based on coolant temperature. And then get rid of all the power enrichment stuff - just shape the fuel table to enrich as necessary. That's how Subaru does it, and I'm told it's how EFI Live does it as well.


The stock model works very well. PE or BE is only a commanded enrichment. I do agree that it's silly to have them enable all in when certain conditions are met. This is why the EFILive COS is nice because it takes the O/L F/A tables and changes the axis to RPM in place of ECT so now it's RPM vs MAP for commanded fueling so it can progressively command richer mixtures as MAP increases. Makes for a much smoother transition in the car. Drawback to it is the MAP scale on the table only goes up to 100kpa so you still either have to use PE to enable boost fueling ratios or anything over 100kpa gets the full enrichment.

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Re: 2-bar / 3-bar hacking

Postby NSFW » Wed Apr 10, 2019 3:09 am

I'd like to go a step further and use load instead of MAP, so the fuel table axes are identical to the spark table axes. That's how it works in my Subaru, and it seems a lot simpler than the PE / BE stuff.

Might need to resize the spark tables to match the dimensions of the fuel tables (the factory spark tables are huge), but it seems like it ought to be do-able.
Please don't PM me with questions about tuning or flashing - start a thread instead. Thanks!

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Re: 2-bar / 3-bar hacking

Postby ShorTuning » Wed Apr 10, 2019 1:10 pm

NSFW wrote:I'd like to go a step further and use load instead of MAP, so the fuel table axes are identical to the spark table axes. That's how it works in my Subaru, and it seems a lot simpler than the PE / BE stuff.

Might need to resize the spark tables to match the dimensions of the fuel tables (the factory spark tables are huge), but it seems like it ought to be do-able.


Yep either way technically works well since they are fairly/sorta proportional to one another.

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Re: 2-bar / 3-bar hacking

Postby Tre-Cool » Wed Apr 10, 2019 11:53 pm

I use efilive for all my ls tuning, in my drag car using the custom os, i have it scaled so that on wastegate 180kpa it's on 1.23g/cyl then start pulling timing based on map upto 285kpa.

the g/cyl reading when on 255kpa is 1.74 looking at my last logs from racewars.

https://youtu.be/f-6pWZ8C0Nk

What would be cool is boost control on a stock ecu.

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Re: 2-bar / 3-bar hacking

Postby NSFW » Mon Aug 26, 2019 6:24 am

160plus told me a while back that he's in contact with someone who basically just hooked up a 3-bar sensor and rescaled the VE table (and probably some other MAP-based tables) to work from zero to 3-bar rather than zero to 1-bar.

The more I think about it, the more I like that idea. Maybe we don't really need a custom OS, maybe we really just need a custom XDF that has the MAP header values scaled appropriately. :)

There's a pretty common technique in the Subaru world where pre-2003 ECUs have a MAF limit of about 300 g/s... You just tell it the injectors are half as big as they really are, and now your MAF scaling effectively goes from 0-600. As a side-effect, the fueling and timing tables (and anything else with a grams-per-cylinder axis) now cover twice the range. With half the resolution, but that's not a problem.

This approach to 3-bar is a similar idea but with a different input.

The biggest thing that I see missing with this approach is that the timing table still tops out a 1.2 g/cyl. Whatever timing you have set at 1.2 is going to carry over for the rest. I think you'd end up tuning the 1.2 row for full boost and just live with sub-optimal timing (and probably higher ETGs) for low boost.

And there's the question of what other tables use MAP as an axis, since those should be rescaled.
And there's the question of what other tables use g/cyl, since those are going to be maxed out.

Far from optimal, but it might work well enough until/unless someone does the work to properly rescale the relevant tables.
Please don't PM me with questions about tuning or flashing - start a thread instead. Thanks!

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