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Author Topic: M3.8.3 pops, bangs - No idle in Overrun process  (Read 945 times)
marantzvieta
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« on: August 11, 2024, 04:40:17 PM »

Hi everbody, have asked this in other old topics but seem to not have work,

I come from a well tuned 8D0907558E M3.8.2 ecu for 1.8t engine (AEB) i did myself. Now, looking for further improvements and upgrades, I swapped the ecu to AGU 06A906018AQ M3.8.3, which I can tune through OBD port (previous was with chips). New ECU works, I converted all my tune parameters from M3.8.2 to M3.8.3, as several axis change, and car runs like a champ, like it did before (167,5g/s at 6200rpm).

Of course not everything could work with the swap: I had working gargles and some subtle pops when shifting. Anyone with M3.8 ecus that has done pops or similar knows that the first step is to change TVSAM.0 and TVSAM.1 maps (KFTVSA in ME7), which controls the delay time for the Overrun function to kick in, so it stays in "idle" mode for a bit longer injecting fuel with delayed ignition.

- So normal behaviour of the engine modes is: Throttle -> Idle -> Overrun / where the time in IDLE is controlled by TVSAM maps. This works in my M3.8.2 ecu.

- But in M3.8.3, no matter what values I configure in TVSAM, it goes straight from Throttle to Overrun without going through Idle mode (so no gargles or pops)

Does anybody know if there is anything i'm missing in M3.8.3? I am kind of fed up with this, I have been working on it for three weeks now, looking a ton of maps, and no changes have worked...

I appreciate any help.

Thank you so much. Wink

Best regards,

Marantz
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eliotroyano
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« Reply #1 on: August 19, 2024, 12:51:15 PM »

Hi checkout TLSN for a bigger value that engine load (ms) in overrun. TVSAM will delay overrun process xx seconds. Also revise ignition is already retarded in your logs after take out accelerator pedal.
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marantzvieta
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« Reply #2 on: August 25, 2024, 11:25:07 AM »

Hi checkout TLSN for a bigger value that engine load (ms) in overrun. TVSAM will delay overrun process xx seconds. Also revise ignition is already retarded in your logs after take out accelerator pedal.

Hi Elio, thanks for your help.

I did modify TLSN, as in the A3 ecu was 0 for all values and in the A4 ecu it had other values in it. See the picture attached and values in red in the A3 TSLN map. I assumed this must have been ok if it did work in the A4 ecu. What do you think about it?

TVSAM is 1 second in both ecu's and ignition maps have same values too.

Do you have any other idea? Thanks for your help, very appreciated.

Best regards,

« Last Edit: August 25, 2024, 11:27:43 AM by marantzvieta » Logged
eliotroyano
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« Reply #3 on: August 26, 2024, 05:11:17 AM »

Hi checkout TLSN for a bigger value that engine load (ms) in overrun.
Log your load values during overrun in the rpm zone you want that pops works, then put TLSN in a bigger value than that. For example, 1, 2, etc. TLSN is a threshold part of the fuel cut during overrun function.
« Last Edit: August 26, 2024, 05:14:50 AM by eliotroyano » Logged
marantzvieta
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« Reply #4 on: August 26, 2024, 07:34:38 AM »

Log your load values during overrun in the rpm zone you want that pops works, then put TLSN in a bigger value than that. For example, 1, 2, etc. TLSN is a threshold part of the fuel cut during overrun function.

Hi mate, thank you so much for your suggestion, it is a very good idea. Will make it with both ECUs to compare and try to find the exact reason to have to use different values in such similar files.

Will report back with findings.

Best regards,
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marantzvieta
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« Reply #5 on: August 26, 2024, 04:07:11 PM »

Log your load values during overrun in the rpm zone you want that pops works, then put TLSN in a bigger value than that. For example, 1, 2, etc. TLSN is a threshold part of the fuel cut during overrun function.

Hi Elio,

I did what you asked to log the load values in overrun. As you can see on the excel file attached with both logs side by side, 558E load in overrun is about 0,4-0.5, whereas in 018AQ is 0,6-0.7

I do not understand where this difference comes from... Also, I do not understand why if 0.4-0.5 load is bigger than what I have in TLSN, the overrun delay does not work in one ecu but does in another...

I also made a log of the throttle-idle-overrun process standing still, revving in neutral, to watch the differences too. As you can see 018AQ will not go into idle below load 1, but 558E does and gargles nice (see values like 0.35, 0.60, 0.95...)

Are we missing something or is it something I am not seeing? I know there might be ways that people do in M3.8.3 ecus, but trying to find a logical explanation when comparing how these two work is driving me nuts...

Thank you for your invaluable help.

Best regards,
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eliotroyano
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« Reply #6 on: August 26, 2024, 04:48:50 PM »

Hi Elio, I did what you asked to log the load values in overrun. As you can see on the excel file attached with both logs side by side, 558E load in overrun is about 0,4-0.5, whereas in 018AQ is 0,6-0.7
I do not understand where this difference comes from... Also, I do not understand why if 0.4-0.5 load is bigger than what I have in TLSN, the overrun delay does not work in one ecu but does in another...

Both ECUs generate different load values in different conditions, and the effect is cumulative. In general I will go with TLSN at 1.5 or 2ms at the rpm range you want and pops will be there the TVSAM time you request. TLSN will activate overrun function after load xx ms waiting a TVSAM delay in seconds. If you select TLSN lower than your engine lower overrun load value you will not have fuel to burn and you will no have pops, or just very few ones.
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marantzvieta
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« Reply #7 on: September 01, 2024, 04:15:34 AM »

Both ECUs generate different load values in different conditions, and the effect is cumulative. In general I will go with TLSN at 1.5 or 2ms at the rpm range you want and pops will be there the TVSAM time you request. TLSN will activate overrun function after load xx ms waiting a TVSAM delay in seconds. If you select TLSN lower than your engine lower overrun load value you will not have fuel to burn and you will no have pops, or just very few ones.

HI mate, sorry I could not answer or test it before. Yesterday I followed your recomendations and put 1,5ms first try and 2ms second try all over the map, and it still does not behave as expected. It did though go into idle sometimes (which it did not before) and when it did it gargled as before for the moments idle showed up on vagcom. So there's been some change but it definetly does not respect delay in TVSAM.

Do we know what TLSN exactly does? Map name is tl Schubabschaltung, which translates i suppose as Load thrust cut-off/shutdown (overrun?) This I suspect is load during overrun, so I do not understand why it affects for the proces... Do you know if there is another map in ME7 which does the same although it is not called the same, that we can read about?

I'm just trying to find a logical path to what the ecu is doing and to what we're trying to achieve.

Thank you for your help and sharing your knowledge. It is very useful.

Best regards,
« Last Edit: September 01, 2024, 06:10:18 AM by marantzvieta » Logged
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