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.

Best regards,

Marantz

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,

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,

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.