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Author Topic: MAF 3" and flow stopped on 262 g/s  (Read 6505 times)
krzysiek50
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« on: November 04, 2019, 10:54:29 AM »

Hi. I have VR6 turbo (AUE, 022906032E) and problem with MAF. In logs flow stopped everytime  on 262 g/s, but in MLHFM max flow is rated to 310g/s. Voltage measured at MAF output is 5V on 1bar boost, however at 262 g/s voltage should be about 4,76V. WTF? Do i need remove some limitter in bin file?
« Last Edit: November 04, 2019, 10:56:37 AM by krzysiek50 » Logged
fluke9
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« Reply #1 on: November 08, 2019, 12:43:36 PM »

Are you sure you measured the output of the MAF, not the supply voltage ?
When does it actually hit like 4.5 Volts ?

Is this a Stock MAF or bigger one?
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Blazius
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« Reply #2 on: November 08, 2019, 05:01:29 PM »

im pretty sure you need to take the 200kg/h offset in the max maf limit maps , if its a Bosch one.
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RBPE
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« Reply #3 on: November 09, 2019, 06:46:05 AM »

Unless you're running custom code for boost/post ambient pressures, you haven't underscaled the HFM to cater for it.
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krzysiek50
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« Reply #4 on: November 12, 2019, 09:59:12 AM »

Are you sure you measured the output of the MAF, not the supply voltage ?
When does it actually hit like 4.5 Volts ?

Is this a Stock MAF or bigger one?

Yes, i'm sure, it was ~5,05V on output. This is stock  3" MAF.

im pretty sure you need to take the 200kg/h offset in the max maf limit maps , if its a Bosch one.

Now offset is equal 200kg/h. You can see this in my bin file.

Unless you're running custom code for boost/post ambient pressures, you haven't underscaled the HFM to cater for it.

What do you mean talking about underscaling HFM? I have stock MAF and stock KLHFM (only for idle  is slightly corrected). Do you think changing to bigger housing and underscaling KLHFM will help?
Can you take a look on my file? Maybe you find what is wrong, because i don't have any ideas.
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_nameless
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« Reply #5 on: November 12, 2019, 10:04:26 AM »

im just going to throw it out there with vrts ive always seen the maf stop flowing around 4.7v. underscale and use a larger housing or find the load caps and use a larger housing with more realistic scaling
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fluke9
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« Reply #6 on: November 13, 2019, 04:33:50 AM »

im just going to throw it out there with vrts ive always seen the maf stop flowing around 4.7v. underscale and use a larger housing or find the load caps and use a larger housing with more realistic scaling

Thats why i asked, according to the specs they should ceil at ~4.5v not 5v.
5,05v sounds more like the supply not the output.

For my supercharged 3.0 GTV with a really old Motronic only used for igniton (Megasquirt for fuel) i had to limit the hot air MAF output otherwise the Motronic would drastically retard ignition or even cut it.
My superhackish but nicely working solution was to put a diode with ~0.4v forward voltage in series, which also resulted in a bit retarded igniton but still got really really nice dyno figures ;-)
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Blazius
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« Reply #7 on: November 13, 2019, 11:27:27 AM »

200 kg/h = 55 g/s , as I said, you are simply hitting maf limit ,unless underscaled or other things. If you look for other max airflow maps they always 200kg /h than it actually is

some people had this "issue" before too on the forum.
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krzysiek50
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« Reply #8 on: November 13, 2019, 11:22:35 PM »

200 kg/h = 55 g/s , as I said, you are simply hitting maf limit ,unless underscaled or other things. If you look for other max airflow maps they always 200kg /h than it actually is

some people had this "issue" before too on the forum.

Change offset to 0?  I understand that offset is a limitation to getting a full airflow reading.
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nyet
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« Reply #9 on: November 14, 2019, 12:02:41 AM »

Change offset to 0?  I understand that offset is a limitation to getting a full airflow reading.

No, that is insane.

Offset is there to support MAFs that can report negative flow.

The limitation here is the voltage. Use a larger housing if you are anywhere near 4.7v

This has literally nothing to do with offset.
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« Reply #10 on: March 31, 2020, 12:12:49 AM »

MLMAX = 1000kg/h.
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