mat/clt correction mod request

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mat/clt correction mod request

Postby Marissp » Sat Jun 24, 2017 1:09 pm

Hello can someone make a mod to latest ms2extra firmware? I want to test old iat heatsoak problems by modified mat/clt correction table. What i am ask is to make simple 3d table x air flow vs y mat vs z mat correction adder in % to existing mat curve.
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Re: mat/clt correction mod request

Postby Marissp » Sun Jun 25, 2017 11:32 am

Isn't anyone intrested or is this too complicated? Doesn't anyone else have heatsoak issues? I think this would work better than to edit the mat density curve, because it does not hurt the "ideal gas law" at all possible airflows, just at specific mat/airflow condition. And this will not kick in mat timing retard, like mat/clt blend does.
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Re: mat/clt correction mod request

Postby robs » Sun Jun 25, 2017 4:31 pm

There's not much going on in MS2 development with the main focus on MS3. Besides that, the latest firmware uses up nearly all the RAM and most of the flash, so enhancements are pretty tricky.

I understand what you're asking for and I don't think it'd be hard to do. OTOH there might be simpler ways to achieve it. e.g. airflow based on the Whittlebeast idea of MAPxRPM with just a simple x->y lookup (rather than x,y->z).

It does strike me that different setups with sensors mounted in various places and with/without turbos have their own problems, all lumped together as "heat soak". That's just the impression I have from reading around here. I've only tuned my two Megasquirted cars. Can you give a more specific definition of the heat soak problem you're addressing?

Have fun,

Rob.
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Re: mat/clt correction mod request

Postby Marissp » Mon Jun 26, 2017 3:08 am

Ok, my setup is mercedes m103 with turbo. Iat sensor is mounted before throttle valve, and there is hose to idle valve, iat is in the middle of "junction", so when car idles there still air passes thru iat sensor.
Everything works fine, except long idle when car is not driving. Then i see as my iat temp rises slowly as my ego correction rises too till max, (15%), so that mean, iat reading is not correct at low airflow at bigger temps.
Marissp
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Re: mat/clt correction mod request

Postby robs » Mon Jun 26, 2017 4:58 pm

That doesn't seem to make much of a case for your suggested solution. Why not just an idling/not idling condition rather than a table?

You want to discount the MAT under certain conditions. The main question I have is what do you use instead?

It seems to me to be a bit like the baro question: the manifold pressure tells you most of what you need to know, but the ambient air pressure also affects volumetric efficiency. Most (I presume) don't run a baro sensor, and make do with a one-off reading of atmospheric pressure before starting the engine. Purists might consider this a bit of a hack.

With air temperature, if you know the true temperature of the air at the intake, you know its density, but it's difficult to get the true temperature at low airflows. While this isn't the same as baro, I wonder if a similar "hack" might help: transition from the ambient temperature at low airflows to the manifold temperature at high airflows. Unfortunately, you can't rely on the initial MAT being the ambient temperature. Perhaps add another sensor behind the bumper? Or do we just assume 25C and find it idles leaner/richer on colder/hotter days?

Have fun,

Rob.
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Re: mat/clt correction mod request

Postby Marissp » Tue Jun 27, 2017 4:49 am

Yes i tought about the idea of two sensors, lets say i can switch from one to another via relay, that can be driven thru spare outputs at specific condition. But i want to try idea about air density correction at specific iat and airflow or map*rpm .
Marissp
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Re: mat/clt correction mod request

Postby robs » Tue Jun 27, 2017 3:10 pm

Minor point: rather than use a spare output to switch a relay it would seem better to use one of the spare ADC ports and have both inputs available all the time.

Main point: the table you're asking for will give a fixed adjustment for a given airflow and MAT, but I strongly suspect that the ambient air temperature would affect this adjustment. You'll get it well tuned in summer, then find it's off the mark in winter.

I suppose there's only one way to find out, and that's to try it in the code. I'm willing to have a go at it despite my doubts. Let's nail down exactly what you want to try. We can probably get quicker progress via e-mail: robsproj9@gmail.com.

Have fun,

Rob.
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