MAF wish list

Testing and development of Megasquirt 3

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Re: MAF wish list

Postby jsmcortina » Thu May 17, 2012 4:38 pm

techsalvager wrote:As I have stated before the commanded fuel table and the closed loop fuel table are the same table called the AFRtarget table.
You can not have wideband controlled closed loop fueling and your main commanded fuel tables different as they are the same one.
See the issue.

If you want to adjust your fuelling away from the MAF calcs you should use VE2 as a trim table as previously discussed. Fudging the AFR table is the wrong way of doing it and that's why you have created a problem for yourself.

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Re: MAF wish list

Postby techsalvager » Thu May 17, 2012 4:51 pm

jsmcortina wrote:
techsalvager wrote:As I have stated before the commanded fuel table and the closed loop fuel table are the same table called the AFRtarget table.
You can not have wideband controlled closed loop fueling and your main commanded fuel tables different as they are the same one.
See the issue.

If you want to adjust your fuelling away from the MAF calcs you should use VE2 as a trim table as previously discussed. Fudging the AFR table is the wrong way of doing it and that's why you have created a problem for yourself.

James


I don't want to adjust my fueling away from MAF calcs, I"ve mentioned already.
I don't want to fudge the AFR table.
Why do you think I do?
I have never fudged the AFR table. I have found the issues with the current implementation and found a proper way to get around those issues while still maintain proper usage of the MAF system.

I want all fueling based off the MAF sensor airflow algothrim.
If I put in lambda 1 I expect it to show up as lambda 1
if I put in lambda .78 I expect it to show up as lambda .78

The only way currently that I can keep lambda 1 at low medium loads is running narrowband closed loop.
that way the AFRtarget table will be ONLY the commanded fuel table. It won't effect closed loop operation. If you run wideband based closed loop operation then the afrtarget table will effect both closed loop operation and your commanded fuel table.

I have no want\need for a trim table

the MAF fuel table and the closed loop target table need to be separated or there needs to be a power enrichenment table.
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MAF wish list

Postby muythaibxr » Thu May 17, 2012 6:09 pm

Why would you want the "commanded afr" and the closed loop target for the same load and rpm to be different? That doesn't make any sense, and I think that is where we are not understanding what you want.

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Re: MAF wish list

Postby ashford » Thu May 17, 2012 8:16 pm

i think he's talking about "incorporate afr". i use map for spark, trim and afr table, it seems to work for me
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Re: MAF wish list

Postby techsalvager » Thu May 17, 2012 8:26 pm

ashford wrote:i think he's talking about "incorporate afr". i use map for spark, trim and afr table, it seems to work for me

I am not
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Re: MAF wish list

Postby jsmcortina » Fri May 18, 2012 2:57 am

techsalvager wrote:a power enrichenment table.

What's one of those?

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Re: MAF wish list

Postby techsalvager » Fri May 18, 2012 5:31 am

jsmcortina wrote:
techsalvager wrote:a power enrichenment table.

What's one of those?

James


Power Enrichment

A carburetor or fuel injection system for a reciprocating engine that enriches the fuel-air mixture when the engine is operating at high power settings.

Like it says going above a certain set condition you change from running at stoich to running richer.
TPS% above certain point, and or calculated load above a certain point

so you would have TPS% vs RPM and calculated load vs RPM tables

So the power enrichment table would be RPM vs Lambda and would dictate your fueling once you enter PE mode.

Why would you want the "commanded afr" and the closed loop target for the same load and rpm to be different? That doesn't make any sense, and I think that is where we are not understanding what you want.

Ken


Why do I want to waste gas at mild acceleration if I have no need for it?
No one wants to waste gas unless they need to or its a strictly race setup.
But at the same time, if I mash the throttle and I want to move, it better add in the fuel to accelerate and make the power. This is exactly why

What if my o2 sensor goes bad, I want to err back to my main commanded fuel table which should be separate from the closed loop fuel table
Last edited by techsalvager on Fri May 18, 2012 7:27 am, edited 5 times in total.
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Re: MAF wish list

Postby Matt Cramer » Fri May 18, 2012 5:36 am

But how does your power enrichment table differ from an AFR target table?
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Re: MAF wish list

Postby bubba2533 » Fri May 18, 2012 7:33 am

The only difference that I see is that he wants a way to switch Target AFR based on TPS.

AFR based on LOAD and RPM can already be done with the AFR table.
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Re: MAF wish list

Postby techsalvager » Fri May 18, 2012 8:01 am

Matt Cramer wrote:But how does your power enrichment table differ from an AFR target table?


The problem with the AFRtarget table is does to many things together.

In MAF \ MAFMAP mode it acts as the Main commanded fuel table and if you have wide band closed loop enabled it also acts as the closed loop commanded fuel table.

In Speed density mode with incoraprate AFR on
It acts as closed loop commanded fuel table with wide band closed loop enabled and it acts as the Main commanded fuel table as well.
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Postby muythaibxr » Fri May 18, 2012 9:09 am

Why is that a problem? Why do you need 2 tables? Why would tou want a closed loop target that is different from the AFR you are telling the ECU to run?

Your "power" table is handled by making the high load portions of your single AFR table richer.

The problem here is that none of your reasons for wanting to separate AFR from closed loop target make any sense to us.

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MAF wish list

Postby muythaibxr » Fri May 18, 2012 9:12 am

Also, AFR is not a commanded fuel table. In SD, the VE controls the commanded fuel and the AFR sets the actual AFR you want to see. In MAF, the MAF itself and its transfer function take the place of VE, and the AFR table retains its purpose.

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Re: MAF wish list

Postby techsalvager » Fri May 18, 2012 8:52 pm

How can I run stoich at 60-100% load and say 2000-4000 rpm under mild acceleration?
How can I run richer then stoich at 60-100% load around the same 2000-4000 rpm under hard acceleration and wide open throttle?

there is places that I don't want to run rich at under certain conditions and there are the same places I want to run rich at the same location under different conditions.

using the AFRtarget table with no closed loop operation.
under maf mode, putting lambda 1 commands lambda 1 based off the inputs the ecu uses and needs. If you put lambda 1 and you get lambda .95 then there is an issue, most likely transfer function is wrong.
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Re: MAF wish list

Postby techsalvager » Fri May 18, 2012 9:02 pm

Matt Cramer wrote:Decouple closed loop boost control from fuel load so that it would either use the MAP sensor in MAF mode, or if no MAP sensor present, use a MAFMAP approximation for boost.

not sure its a good idea to use anything but a map sensor for boost control. I need to do more data analysis on my car and another car with a turbo setup.
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Re: MAF wish list

Postby bubba2533 » Fri May 18, 2012 9:11 pm

techsalvager wrote:How can I run stoich at 60-100% load and say 2000-4000 rpm under mild acceleration?
How can I run richer then stoich at 60-100% load around the same 2000-4000 rpm under hard acceleration and wide open throttle?

there is places that I don't want to run rich at under certain conditions and there are the same places I want to run rich at the same location under different conditions.

using the AFRtarget table with no closed loop operation.
under maf mode, putting lambda 1 commands lambda 1 based off the inputs the ecu uses and needs. If you put lambda 1 and you get lambda .95 then there is an issue, most likely transfer function is wrong.


bubba2533 wrote:The only difference that I see is that he wants a way to switch Target AFR based on TPS.

AFR based on LOAD and RPM can already be done with the AFR table.


As I stated before the only thing this would require in addition to the current code is a target AFR based on TPS. This could be done with a TPS switch point to target a specific AFR above a specific TPS % and it could also be done with AFR table switch based on TPS %.
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Re: MAF wish list

Postby techsalvager » Fri May 18, 2012 9:13 pm

bubba2533 wrote:
techsalvager wrote:How can I run stoich at 60-100% load and say 2000-4000 rpm under mild acceleration?
How can I run richer then stoich at 60-100% load around the same 2000-4000 rpm under hard acceleration and wide open throttle?

there is places that I don't want to run rich at under certain conditions and there are the same places I want to run rich at the same location under different conditions.

using the AFRtarget table with no closed loop operation.
under maf mode, putting lambda 1 commands lambda 1 based off the inputs the ecu uses and needs. If you put lambda 1 and you get lambda .95 then there is an issue, most likely transfer function is wrong.


bubba2533 wrote:The only difference that I see is that he wants a way to switch Target AFR based on TPS.

AFR based on LOAD and RPM can already be done with the AFR table.


As I stated before the only thing this would require in addition to the current code is a target AFR based on TPS. This could be done with a TPS switch point to target a specific AFR above a specific TPS % and it could also be done with AFR table switch based on TPS %.

I explained the gist of it already back on page 1
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Re: MAF wish list

Postby bubba2533 » Fri May 18, 2012 9:24 pm

Obviously it wasn't a good enough explanation or they would of already understood what you were trying to do. Just saying...
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Re: MAF wish list

Postby muythaibxr » Fri May 18, 2012 10:01 pm

techsalvager wrote:How can I run stoich at 60-100% load and say 2000-4000 rpm under mild acceleration?
How can I run richer then stoich at 60-100% load around the same 2000-4000 rpm under hard acceleration and wide open throttle?

there is places that I don't want to run rich at under certain conditions and there are the same places I want to run rich at the same location under different conditions.


I would say you can't be at 60-100% load and have mild acceleration AND be 60-100% load at the same RPM and have hard acceleration. The only thing you can change to cause that is the gear you're in. And in that case you wouldn't want to have different AFRs at those same loads... you'd want higher loads to be richer.

You can be at 90-100% load and have hard acceleration (for example), or be at 60-90% load and have mild-medium acceleration. In which case you'd just put Stoich values between 60-90%, and richer than stoich at 90-100%.

Again, what you're asking for doesn't make sense.

using the AFRtarget table with no closed loop operation.
under maf mode, putting lambda 1 commands lambda 1 based off the inputs the ecu uses and needs. If you put lambda 1 and you get lambda .95 then there is an issue, most likely transfer function is wrong.


Yes, so you'd fix your transfer function to give you 1 lambda where you ask for 1 lambda, and in the meantime, the closed loop algorithm would correct the fueling to lambda 1.

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Re: MAF wish list

Postby muythaibxr » Fri May 18, 2012 10:06 pm

bubba2533 wrote:As I stated before the only thing this would require in addition to the current code is a target AFR based on TPS. This could be done with a TPS switch point to target a specific AFR above a specific TPS % and it could also be done with AFR table switch based on TPS %.


Again, why would you do this? TPS% does not determine load directly... For example, going up a hill the load is higher than coming down with the throttle position the same in both places.

As you open the throttle, more air goes in, you lose vacuum, the load calc (MAFMAP) increases, and you set that part of the existing AFR table richer. There's no need for multiple tables when 1 table will do what you need. Even if the TPS doesn't move, if load increases, you want to run richer, and if load decreases you want to run leaner. That is still done on 1 table. I see no need to separate the target table into 2 tables.

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MAF wish list

Postby subwoofer » Fri May 18, 2012 11:07 pm

muythaibxr wrote:Again, why would you do this? TPS% does not determine load directly... For example, going up a hill the load is higher than coming down with the throttle position the same in both places.

As you open the throttle, more air goes in, you lose vacuum, the load calc (MAFMAP) increases, and you set that part of the existing AFR table richer. There's no need for multiple tables when 1 table will do what you need. Even if the TPS doesn't move, if load increases, you want to run richer, and if load decreases you want to run leaner. That is still done on 1 table. I see no need to separate the target table into 2 tables.

Ken


I am not an expert, but I don't agree with the load argument. If going up a hill, the steady state is reached at a different rpm than while going down hill, so the throttle position should actually approximate load for that rpm. Power output would be wildly different, though.

I still think TPS based AFR table switching is a good idea, a table switch is the only way to change AFR targets from lean of stoich to safely rich of stoich safely while under load. Interpolation would possibly put you bang in the middle of the detonation zone.
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