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maf tuning on motec

 
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Mon Feb 04, 2013 7:44 pm    Post subject: maf tuning on motec Reply with quote

so I was interested in the m84 that motec has but what holds me back is the maf tuning on it, seems there not much info out there and I rather not drop money on it without knowing how it works.

From what I gathered its mainly IPW tuning on the motec m84 for SD and alpha N, now I was told by one of the motec engineers\techs at PRI that it still is IPW tuning using a MAF, or atleast thats what I got from him. What makes me think that is odd is the fact there is a calibration table for the maf input. Does anyone have info on this?
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efiguy
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Joined: 17 Nov 2003
Posts: 727
Location: So Cal

PostPosted: Fri Aug 30, 2013 2:37 pm    Post subject: Reply with quote

We have the MAF connected to our M800 at EFI University on one of our test vehicles. Essentially, nothing changes about the way that Motec uses the info.

The input calibration is to scale the MAF value to the voltage signal.

The problem is, that information is not handled as "MAF" in the software, but rather as an indication of engine load (or "efficiency" in Motec speak).

This means, that when the signal from the maf sensor reads higher or lower, it only serves to move the efficiency data point to a new table address and there it accesses a new value of injector pulsewidth (or ignition timing, etc).

In a true MAF based system, the ecu would simply use the actual MAF value to calculate a new new fuel requirement and compare that to a stored value for injector flow rate and thus, come up with a new injection time as a percentage of increase or decrease in mass flow.
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joe90



Joined: 19 Mar 2013
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Location: under the car

PostPosted: Fri Aug 30, 2013 4:26 pm    Post subject: Reply with quote

In proper factory MAF EFI systems the "load" axis is the MAF value /RPMs (A/N)
In an SD system the load is the MAP value.
In Alpha N the load is the TPS %.

Don't know how that works in a motec though?
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baselkwt



Joined: 21 Jul 2013
Posts: 9

PostPosted: Sat Aug 31, 2013 4:47 am    Post subject: Reply with quote

Maf systems, like that on factory cars dont have the MAF as a load axis on the fueling table.

Its just a 2d MAF table, where volts correlates to air in grams per second.

which is then divided by the number of cycles per second and then divided by number of cylinders that the MAF feeds (if each bank has its own maf)

then you get grams per cylinder, and based on that number the ecu can calculate the injector pulsewidth required to maintain correct (or target) fueling.

engine rpms do not need to be an axis on a table like this (because it is used in the calculation)

but you still need a target afr table, or a lambda table (with a stoich setpoint)

motec treats the maf like a map, where it is maf vs rpm, which isnt the same thing.

however the MAF should be the load axis in the timing table, just like you would do with speed density.
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joe90



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PostPosted: Sat Aug 31, 2013 6:33 am    Post subject: Reply with quote

You're confused.
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TurboNova



Joined: 08 Dec 2004
Posts: 1158
Location: Lake Havasu City, AZ

PostPosted: Sat Aug 31, 2013 6:49 pm    Post subject: Reply with quote

joe90 wrote:
In proper factory MAF EFI systems the "load" axis is the MAF value /RPMs (A/N)
In an SD system the load is the MAP value.
In Alpha N the load is the TPS %.

Don't know how that works in a motec though?


Ben just explained it above. In Motec it just uses the MAF value as the "load" instead of map or tps. It has a 0-5v signal just like the other two.

It does not look at it like a factory MAF curve setup.
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Grocerius Maximus



Joined: 02 Apr 2006
Posts: 300
Location: McKinney TX USA

PostPosted: Sat Aug 31, 2013 11:06 pm    Post subject: Reply with quote

Mass per induction, they are g/rev X 100 on the 'efficiency' axis if you use a PROPERLY calibrated MAF. Couldn't be simpler, know your injectors, fuel, and fuel pressure, write a fuel map with a spreadsheet to within a percent or two.

Quote:
The Efficiency Point is the Air Mass per induction and is derived
from Mass Air Flow (MAF) and Engine RPM as follows:

Efficiency Point = MAF / inductions per rev / (RPM/60) * 100


May be different for Hz output sensors for the M84 as MAF input is locked to AV3.
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baselkwt



Joined: 21 Jul 2013
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PostPosted: Sun Sep 01, 2013 8:41 am    Post subject: Reply with quote

Quote:
You're confused.


only a little.
the information is there. just not very well organised.

Quote:
May be different for Hz output sensors for the M84 as MAF input is locked to AV3.


yeah the m84 is very limited in its functions. i tried it once, motec dont give you much flexibility with it.
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Wolf_Tm250



Joined: 26 Aug 2006
Posts: 475
Location: Parma - Italy

PostPosted: Sun Sep 08, 2013 1:46 am    Post subject: Reply with quote

TurboNova wrote:
joe90 wrote:
In proper factory MAF EFI systems the "load" axis is the MAF value /RPMs (A/N)
In an SD system the load is the MAP value.
In Alpha N the load is the TPS %.

Don't know how that works in a motec though?


Ben just explained it above. In Motec it just uses the MAF value as the "load" instead of map or tps. It has a 0-5v signal just like the other two.

It does not look at it like a factory MAF curve setup.



Just to see if I understood correctly...

so the table have worse resolution the lower the rpm?
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Grocerius Maximus



Joined: 02 Apr 2006
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Location: McKinney TX USA

PostPosted: Mon Sep 09, 2013 2:22 pm    Post subject: Reply with quote

Mx00 can use Hz or AV MAF, looks like M84 is limited to an AV input type. You can calibrate the MAF input to exact spec if you have data from the MAF mfg. When using MAF as your Efficiency, it uses grams per rev (not induction) x 100. See F1 on the software. I've used it before, its simple and accurate, you can do your fuel table via spreadsheet within a percent without ever firing the engine with good injector data. If its a VOLUME airflow MAF, and not a true mass airflow sensor, obviously there will need to be a temp correction from temp at the sensor element.
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Wolf_Tm250



Joined: 26 Aug 2006
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Location: Parma - Italy

PostPosted: Tue Sep 10, 2013 4:44 am    Post subject: Reply with quote

Grocerius Maximus wrote:
Mx00 can use Hz or AV MAF, looks like M84 is limited to an AV input type. You can calibrate the MAF input to exact spec if you have data from the MAF mfg. When using MAF as your Efficiency, it uses grams per rev (not induction) x 100. See F1 on the software. I've used it before, its simple and accurate, you can do your fuel table via spreadsheet within a percent without ever firing the engine with good injector data. If its a VOLUME airflow MAF, and not a true mass airflow sensor, obviously there will need to be a temp correction from temp at the sensor element.




Motec's efficiency is gr/sec or gr/rev?

EDIT: sorry, found...
it's gr/rev so the map has good resolution at any rpm...
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Grocerius Maximus



Joined: 02 Apr 2006
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Location: McKinney TX USA

PostPosted: Wed Sep 11, 2013 7:48 am    Post subject: Reply with quote

You don't have to set it up in a 'traditional' aftermarket ECU fashion, with fixed definition tables, you can change the axis parameters on virtually ANY table (well, except M84). It can be set up in a very OEM ECU type fashion with a little imagination, regardless of what you define 'load' or 'efficiency' as. This would of course also apply for any other ECU that allows you to change axis parameters, and even some that don't, think outside of the box they give you to work with.
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