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Author Topic: How to control/switch pops and bangs through A/C?  (Read 17609 times)
rus4play
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« on: May 27, 2020, 04:43:58 PM »

Hey,
I've seen a lot of tuners say its possible on similar car like mine.

Audi S6 C5 4B 2004 4.2 ANK
Serial Numbers:
0261207632 BOSCH
4D0907559AB AUDI
Me 7.1.1

But I don't understand how it should work to switch pops bangs through A/C. I got pops and bangs through altering some tables: KFNWEGM, KFZWMN and KFZWOP. But I need to flash the ECU everytime to disable/enable it.

I've found DNWEK map which only contains the RPM value 1x1 and tried setting it to 8000 but it didnt work. I'm also searching the maps myself in my Dump maybe I didn't find the right one because its only one value and so its very hard to find for me as a beginner.

Maybe someone can explain it to me or show some other way? Thanks a lot!
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fknbrkn
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« Reply #1 on: May 28, 2020, 12:42:10 AM »

What is the a/c? Air condition?
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Jorgeminator
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Golf MkIV 1.8T AUM


« Reply #2 on: May 28, 2020, 09:46:24 AM »

But I don't understand how it should work to switch pops bangs through A/C. I got pops and bangs through altering some tables: KFNWEGM, KFZWMN and KFZWOP. But I need to flash the ECU everytime to disable/enable it.

I've found DNWEK map which only contains the RPM value 1x1 and tried setting it to 8000 but it didnt work. I'm also searching the maps myself in my Dump maybe I didn't find the right one because its only one value and so its very hard to find for me as a beginner.

Maybe someone can explain it to me or show some other way? Thanks a lot!
DNWEK normally adds 160 RPM to the overrun fuel-cut threshold whenever the AC compressor is active. By setting it so that the total fuel-cut threshold is above your rev-limiter you are basically disabling overrun fuel-cut for the whole RPM range as long as the AC compressor is running. You still need to retard the timing in the areas required, otherwise you will still burn all the fuel in the cylinder.
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Sandstorm3k
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« Reply #3 on: May 28, 2020, 10:00:32 AM »

DNWEK normally adds 160 RPM to the overrun fuel-cut threshold whenever the AC compressor is active. By setting it so that the total fuel-cut threshold is above your rev-limiter you are basically disabling overrun fuel-cut for the whole RPM range as long as the AC compressor is running. You still need to retard the timing in the areas required, otherwise you will still burn all the fuel in the cylinder.

Interesting, i'm willing to try this little "hack" out, though i don't quite understand the logic behind this. What is the connection between AC and overrun? Sorry if i misunderstood.
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Jorgeminator
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« Reply #4 on: May 28, 2020, 10:03:50 AM »

It's all in the Funktionsrahmen, read it. Wink E.g. when you completely let off the throttle in 3rd gear at 3000 RPM the ECU cuts fuel until the RPMs dip below the cut-off threshold in KFNWEGM, 1120 RPM for a fully warmed up engine in 3rd gear. It then starts injecting fuel again, otherwise you would just continue engine braking until you come to a complete stop. DNWEK just adds 160 to 1120 RPM, making the threshold 1280 RPM when the AC compressor is running. The compressor robs the engine of some torque, I guess that's why they increase the threshold slightly when it's running.
« Last Edit: May 28, 2020, 10:22:28 AM by Jorgeminator » Logged
Sandstorm3k
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« Reply #5 on: May 28, 2020, 11:29:44 AM »

It's all in the Funktionsrahmen, read it. Wink E.g. when you completely let off the throttle in 3rd gear at 3000 RPM the ECU cuts fuel until the RPMs dip below the cut-off threshold in KFNWEGM, 1120 RPM for a fully warmed up engine in 3rd gear. It then starts injecting fuel again, otherwise you would just continue engine braking until you come to a complete stop. DNWEK just adds 160 to 1120 RPM, making the threshold 1280 RPM when the AC compressor is running. The compressor robs the engine of some torque, I guess that's why they increase the threshold slightly when it's running.
Thanks for the clarification, i understand now. I looked at the "Funktionrahmen" but didn't quite understand yet. So i could set DNWEK to something like 6000 (max RPM= 6800), overrun will always be disabled when AC is running.

Thanks again! As i could not find much regarding DNWEK online. If i can find the value tonight in my BIN i'll give it a go!
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Jorgeminator
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« Reply #6 on: May 28, 2020, 11:53:09 AM »

Just don't destroy your exhaust/cat  Grin
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bamofo
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« Reply #7 on: May 28, 2020, 12:31:42 PM »

Just hook it off Cruise Switch. Its way easier...
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Sandstorm3k
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« Reply #8 on: May 28, 2020, 12:32:49 PM »

Just don't destroy your exhaust/cat  Grin
Thanks for the heads up haha, running catless downpipe and a milltek exhaust so should be good!
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Sandstorm3k
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« Reply #9 on: May 28, 2020, 12:33:54 PM »

Just hook it off Cruise Switch. Its way easier...
Is it really though, you are referring to map switching i suppose?
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bamofo
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« Reply #10 on: May 28, 2020, 12:36:22 PM »

Is it really though, you are referring to map switching i suppose?

Yes it really is. You just set a JNB for the Cruise control Main switch on your ASM code and off you go.

If your just using the rev limiter for cut then this will not work. But my code runs stationary Limiter at 5400 (soft limit). and Hard cut (pops and bangs) at 4800. one line of code. Jump out of logic if Cruise is set. Done.
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Sandstorm3k
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« Reply #11 on: May 28, 2020, 02:19:41 PM »

It's all in the Funktionsrahmen, read it. Wink E.g. when you completely let off the throttle in 3rd gear at 3000 RPM the ECU cuts fuel until the RPMs dip below the cut-off threshold in KFNWEGM, 1120 RPM for a fully warmed up engine in 3rd gear. It then starts injecting fuel again, otherwise you would just continue engine braking until you come to a complete stop. DNWEK just adds 160 to 1120 RPM, making the threshold 1280 RPM when the AC compressor is running. The compressor robs the engine of some torque, I guess that's why they increase the threshold slightly when it's running.
Perhaps i've still misunderstood; i went ahead and found DNWEK in my bin, I changed from 160RPM to 6000RPM. But instead of AC switch disabling overrun it instead  disables fuel cut entirely thus popping/banging untill timing is back to standard.
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Jorgeminator
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« Reply #12 on: May 28, 2020, 02:25:30 PM »

Do you mean the AC switch has no effect on the outcome? That's strange. DNWEK is conditional, it depends on the B_koe (compressor on) flag being set, else it won't be considered.

Or, do you mean it crackles all the time when letting off? This approach does just that, basically crackles and bangs all the time while coasting in gear. I've looked at the schematics on how to put a time limit on it, I'll check in again tomorrow.
« Last Edit: May 28, 2020, 02:30:17 PM by Jorgeminator » Logged
Sandstorm3k
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« Reply #13 on: May 28, 2020, 02:46:39 PM »

Do you mean the AC switch has no effect on the outcome? That's strange. DNWEK is conditional, it depends on the B_koe (compressor on) flag being set, else it won't be considered.

Or, do you mean it crackles all the time when letting off? This approach does just that, basically crackles and bangs all the time while coasting in gear. I've looked at the schematics on how to put a time limit on it, I'll check in again tomorrow.
It crackles all the time when letting off, thus disregarding KFTVSA value of 2.5 sec. What i'd like is that AC-on disables overrun and thus also pops&bangs.

Thanks for helping out. May i ask where do you find these schematics? I'd be very interested to have a look myself too!
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Jorgeminator
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« Reply #14 on: May 28, 2020, 02:52:07 PM »

It crackles all the time when letting off, thus disregarding KFTVSA value of 2.5 sec. What i'd like is that AC-on disables overrun and thus also pops&bangs.

Thanks for helping out. May i ask where do you find these schematics? I'd be very interested to have a look myself too!

Overrun & fuel-cut is on page 710 in Funktionsrahmen (Betriebsbereich Schubabschalten/Wiedereinsetzen).
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