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 Post subject: Merpmod IAT compensation for A8DH200Z
PostPosted: Thu Feb 16, 2023 3:05 pm 
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Newbie

Joined: Fri Nov 12, 2021 10:03 pm
Posts: 2
Slightly confused, I can't find the fuel/load IAT compensation for this anywhere.
I have the firmware part decompiled so I can find the merpmod code and start looking for it, but does anyone have defs for this already? Or what I'm looking for?

I have just moved intake air temperature to intake manifold side of the intercooler and see it going leaner as the air temp increases while idling at a steady RPM/coolant temp etc,
so it needs the IAT compensation sorting out a bit.

Thanks


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 Post subject: Re: Merpmod IAT compensation for A8DH200Z
PostPosted: Tue Feb 28, 2023 8:40 am 
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Senior Member

Joined: Thu Dec 18, 2014 10:31 pm
Posts: 1529
Location: oregon
MAF IAT comp.

It's active all the time, for whatever you have put in there, regardless if you're on MAF or not.

Most of Merp patches don't include a standard load/IAT comp, but airmass correction is airmass correction.

A 10% change in g/rev is a 10% change in g/sec.


Attachments:
File comment: I picked the five most reasonable points with the most linear transitions between points, and a temp range that is suitable
image_2023-02-28_003806804.png
image_2023-02-28_003806804.png [ 9.78 KiB | Viewed 901 times ]

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 Post subject: Re: Merpmod IAT compensation for A8DH200Z
PostPosted: Thu May 25, 2023 4:17 pm 
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Joined: Wed Nov 23, 2011 10:57 pm
Posts: 5
jon7009 wrote:
MAF IAT comp.

It's active all the time, for whatever you have put in there, regardless if you're on MAF or not.

Most of Merp patches don't include a standard load/IAT comp, but airmass correction is airmass correction.

A 10% change in g/rev is a 10% change in g/sec.

Merpmod SD calculates with a fixed IAT like Cobb (30C) or why is this huge negative compensation needed? To account for MAF IAT before turbo?
For heat soak related leaning out, I would think the opposite compensation is required?


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 Post subject: Re: Merpmod IAT compensation for A8DH200Z
PostPosted: Thu Jun 01, 2023 5:13 am 
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Experienced

Joined: Sun Jun 28, 2020 6:25 am
Posts: 242
norwn wrote:
jon7009 wrote:
MAF IAT comp.

It's active all the time, for whatever you have put in there, regardless if you're on MAF or not.

Most of Merp patches don't include a standard load/IAT comp, but airmass correction is airmass correction.

A 10% change in g/rev is a 10% change in g/sec.

Merpmod SD calculates with a fixed IAT like Cobb (30C) or why is this huge negative compensation needed? To account for MAF IAT before turbo?
For heat soak related leaning out, I would think the opposite compensation is required?


I'm using pre-turbo IAT and that MAF compensation is actually too rich for me. It depends from setup to setup.

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2011 WRX 6MT ~ Flex Fuel


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