LS1 2-Bar Map Install

[phuz]

Applied the OS upgrade for the 2-Bar MAP on my PCM and set up the Primary VE table accordingly.
Under the PE, Boost Enrichment, I see more confusion which I assume is just a typo.

[ECM] 2370 - Boost Fuel Enable MAP: This is the minimum MAP to enable the Boost Enrich table. Additionally, above this MAP the engine will enter open loop.

So this is the minimum MAP to enable boost enrichment, but also above this MAP it will go into open loop (exit PE)?
I assume that means that below that MAP it will go back into open loop, OR, does it actually go back to open loop and strictly use the VE / BE tables?

[Alvin]

I think they mean open loop in the since that no o2 feedback is being used.

This works just like a normal PE table but vs MAP instead of RPM. Set the enables up so that you use it like you want.

Works great. Been using it for years

[phuz]

I think they mean open loop in the since that no o2 feedback is being used.

This works just like a normal PE table but vs MAP instead of RPM. Set the enables up so that you use it like you want.

Works great. Been using it for years

I think what's great about this, at least from how I perceive it, is that I can still use my existing MAF table for normal drivability and only go into the SD mode when boosting.

[Alvin]

MAF has nothing to do with it being in open loop or not and I think specifically the MAF will not work on GEN 3 2 bar OS's.

[kingtal0n]

I never use closed loop in 2-bar or 3-bar installations unless it has a full time wideband closed loop controller like Holley or Megasquirt or Haltech. The OEM ECU does not offer wideband closed loop so it is obsolete. If you are a beginner it would be important for you to learn how the closed loop function works, as part of natural process, similar to the way we learn pre-calc before calculus and then never use pre-cal again. It is merely historical.

So for example in my 2-bar file, which is tuned in open loop 100% of the time,
https://forum.hptuners.com/showthrea...l=1#post686802

You can see I target wideband a/f ratios, not closed loop or narrowband ratios. This improves fuel economy, keeps plugs cleaner, reduce carbon deposits. All modern Stand-alone ECU have this feature in closed loop but OEM ECU does not so we use OPEN loop to achieve the same affect.

Once you threshold the normal Power Enrichment mode, for example mine is set around 80KPA and maybe 28% throttle, It starts using the power enrichment tables to add EQ ratio on top of the VE tuned valves.
For example if VE table is tuned to 14.5:1 and PE Mode calls for 13.3:1 it will wind up somewhere around 13.1:1 air fuel ratio actual.
This is because the PE Mode assumes the VE table is tuned to stoich 14.7:1 so if you are off by .2a/f ratio then PE will probably be off around the same magnitude, although a/f isn't linear its easy to think about it that way.

Once you meet boost threshold requirements it will jump from PE mode to BE mode, and use BE enrichment values given some boost pressure.
So it will jump from using RPM in PE mode, to using BOOST in BE mode as the target is based on RPM is the PE but based on Boost in the BE mode.

All three tables, VE, PE, BE, work together for smooth transitions into power and boost enrichment during open loop in my file. It never used closed loop, ever, not for 5 years 50,000 miles, I don't even have narrowband oxygen sensor, it is obsolete. The wideband has a narrowband inside it. Some have configurable analog outputs but that is getting beyond the scope of this discussion.

There is also a fourth table to be aware of, its called like "EQ global" or "EQ ratio" or something. I forgot the name. But it will directly influence the VE weights, for example during cold start when coolant is cold, this table uses values like 1.25 instead of 1.00 to give a 25% Increase weight to the VE values which gives us the cold enrichment. This table seems to work both ways as I've used 0.95 values to remove fuel for cruise situations for example.

[phuz]

MAF has nothing to do with it being in open loop or not and I think specifically the MAF will not work on GEN 3 2 bar OS's.

I agree with the first part of this statement, but why would the MAF not work with the 2-bar OS application?

You can see I target wideband a/f ratios, not closed loop or narrowband ratios. This improves fuel economy, keeps plugs cleaner, reduce carbon deposits. All modern Stand-alone ECU have this feature in closed loop but OEM ECU does not so we use OPEN loop to achieve the same affect.

I think I know what you're saying, but I just want to be clear that we're on the same page: you can have closed loop regardless of wideband vs. narrowband (and yes, OEM ECU does not have wideband control). Open loop is strictly table-driven w/o feedback.

[Alvin]

I agree with the first part of this statement, but why would the MAF not work with the 2-bar OS application?

Fairly certain the help file says the MAF is disabled in those OS's and Hptuners support has personally told me so.. albeit a decade ago.

Try it and see what happens. Make big changes to the MAF table and see if it actually does something.

[phuz]

Fairly certain the help file says the MAF is disabled in those OS's and Hptuners support has personally told me so.. albeit a decade ago.
Try it and see what happens. Make big changes to the MAF table and see if it actually does something.

Yeah, just more conflicting information, because this thread seems to state differently, but your suggestion of making a big change to the MAF table to see how it responds, is a good one.
https://forum.hptuners.com/showthrea...-MAF-amp-Boost