NefMoto

I'm getting very close to the 1.5 bar limit of the MAP sensor, so soon will have to go open loop on the N75.  I'm thinking that requested load should be left alone, as otherwise you will run into problems of setpoint being unreachable.  Question is, what to do with PID maps? I will add duty with the linearisation map, but do you zero out the PID settings or leave them as they are?

Rick

I would leave them as they are so that you have a smooth transition between "open loop" and "closed loop" control.

Which map do you change to go open loop?
Kfldimx, do you set this to 100 for open loop?
Kfldrl, would guess needs to be adjusted. 
Once the pid maps are changed do you leave ldrxn alone as well as requested load?

For the record, there is no such thing as open loop boost in the ME7. What we are discussing, is how you control boost pressure once you exceed the limit of the MAP sensor.

thanks, I will look up open loop then, I thought that's what it referred to... no wastegate duty as prescribed by the ecu. 
I'm under the impression the ebc or mbc would need to be used if you are boosting past 22 psi. I would like to write a ko4 tune, so I will be keeping an eye on this topic.

If you boost past 22psi the ECU doesn't know, because it can't read higher than that. Past 22psi the ECU will be unable to control boost, because it can't detect when actual boost exceeds desired boost. The ECU will think desired boost is 22psi and actual boost is 22psi, so everything is perfect, when in really actual boost higher than 22psi.

The only way around this is to use the ECU PID to control boost up to 22psi. Above 22psi you can tune the N75 linearization table to fake control based on RPM, or you can use a MBC or EBC.

alot of dust on here  ;D

Do i need to touch the PID if i plan to go over 1,5 anyway?
in other words: is it necessary to redefine the PID from square one for 1,45 bar in the first step to have a good closed loop boost control. The result of this would be a smooth transition from <1,5bar to more boost, at least in my brain. I dont know  ???

Or is it just not necessary if i aim for 1.8bar ?

The solution is not to run it in open loop, and rescale the pressure in ECU.
Open loop with a bleed valve does not work right, it will overboost horribly in winter and underboost in summer.

And if you change altitude.........

Shit goes bad.

Is this in reference to re-scaling the pressure?

More-so atmospheric density and running fixed DC over the map.
Agreeing with prj.

Copy that. Thanks

Are you pointing me to the 5120hack or what does rescale the pressure mean here?

That is exactly what prj was doing-lol.

thx

sometimes its hard for the non native english users  :-*

There's a nearly finished CB hacked file on here, I'm sure.  Pretty sure it's Dan's!

Can you not set boost up with a gauge/ boost logger on dyno and add a fixed duty cycle to the 1500mbar row on IMX and the ECU will only use that set duty cycle for pressures over 1500mbar and for the RPM sites?  Obvilously need to be setup under engines highest load.

You can, but as DD and prj mention, temperature and altitude will affect what boost you get for a given duty cycle.

another noob question:

This is how it worked in the 10+ years before the 5120hack?
No corrector for IAT and altitude?

Does anyone know how much boost is affected at different altitudes and atmospheric temperatures?

What did the early AGU me3.8 do or was this worked out differently?

There is LDIATA and KFLDIOPU, but trying to control boost using PWM on a bleed valve in open loop is just asking for disaster.
Worst case, fit a MBC in parallel, and set DC to 100% over a certain requested pressure, and let the MBC handle it.

There are some maps that modifies boost (LOAD) base in temperature and/or altitude:
Intake Air Temp: KFLDSAK, KFLDTVAK
Altitude: KFLDSHK.
There are some others but I think these are the most important ones.

There is no boost in M3.8.x. Pressure does not exist in that ECU.

PV = nRT

It is literally baked into the load->boost calculation path.

Please review the s4wiki again.