As stated in the title i'm gauging interest in a auto tune feature for the Baro setting on Speed Density patched roms. After looking at the code for the evo 8 I can say the setting only takes place in 1 function so creating a hop to a new function to set a baro reading based on the map sensor input should be trivial.

Let me know what you guys think. It seems this setting only really effects startups so the plan is to auto tune up the baro with the map sensor only when RPM == 0. The ecu is capable of hitting the function at around 100hz so even on the fastest start I should be able to get it to set before the engine moves an inch.

Thoughts?

 

It would be interesting to test but personally its not needed unless there are substantial changes and even then I bet it would be pretty close. Luke took his Evo from Sea level to 6,000 feet today with some interesting results. Video to follow.

If it affects start up though more than anything (I see where you are going with that), it makes sense that it would be a nice feature.

 

Absolutely do it. Same to you aaron, I wanna hear how it worked out!

 

Baro is used in numerous places throughout the ECU.

Fuel, Timing, Load, Idle, Accel/Decel enrichment...all of them use baro correction of some form.

If you could auto-update the idle and startup sections seperately from the other items though, I think you would be onto a good fix.

Baro has a big impact on startup and idle, I can tell you first hand going from 4200' to 9000' on speed density causes some startup/idle problems. Other then that, SD is fine without baro correction as AFRs were spot on under load.

 

Interested in more of this info.

I'm pretty sure what i can do is adjust baro during startup only put like an RPM cap on it of under 150 rpms? Then when its running put a set baro back into it. Does this sound good?

I'm totally open to how it would be programmed

 

Kinda off topic, but has anyone tried taking baro out of the equation? By making ecu think it stays at one pressure at all times.

 

Thats exactly how the SD patches work right now.

 

I think that would probably work.

The main concern with updating it is that baro is used for finding compensated load. If you allow it to update every time you start the car and then held that value for when it is running, it would move you around in the fuel maps and change the tune daily. If you adjust just while the ECU initializes then lock it at a set value once the engine starts it should work.

 

Thats kinda the idea.

I wont be able to do just initialization since it looks like the function is called in the runtime loop as well as the init functions. So using an RPM cap seems like the best method.

I'm pretty sure we could use the uncompenstated load from the map sensor VE table to use as an axis to the table so even with different sensors it wont move around too much.

We could initially check the RAM for a value and set it to a stock setting then if its under 100RPM adjust the Baro with a table using load and baro settings say like 8 or so in length should be enough?

During cranking the engine RPM should surpass the Baro setup of 100rpm limit and we can wait until the engine reaches a idle speed of like over 500 rpm to set the Baro back to the set 1.010 Bar pressure.

How does this logic strike you?

 

could you add something for the hot start too?

 

I was making it happen on any startup would it be prefered to disable it for certain conditions other than rpm?

 

Any interest in anyone just using the stock map as a constant Baro? I can provide the harness but suck at programming!

 

What did you hook it into?

I think we should try this switching code first it would at least save people money

 

My harness has a baro input, same wires on stock MAF sensor. Should accept a MAP with some work.

Having the car reset baro before every start is a cool idea!

 

I am curious as to what this would really help though. Barometric pressure changes are so minimal unless you have huge variations in elevation, and weather. I am a little SD ignorant so if my question is off key, I can understand.

For the hot start problem, why not just relocate the IAT sensor to the cold side of the FMIC as close to is as possible?