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 Post subject: ms41 m52b28 low rpm hesitation
PostPosted: Tue Oct 07, 2025 4:23 am 
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Joined: Thu Sep 04, 2025 7:19 am
Posts: 12
Hi, tried RomRider to see what can i do for the car - had hesitation in low rpm/ slight throttle application. Before that changed every sensor/fuel pump/maf/lambda/cleaned injectors with new OE/OEM parts (everyone knows that ms41 wants to work almost with VDO stuff only )

also visited a Remap/dyno service with a wideband reading (just to check the car for stock condition and also last time was on the verge of not passing MOT in my country for emissions) , the car showed very lean mixtures below 3500rpm

so decided to try and give it a shot myself (the best remaping services as far as i know are in different part of the country - Bulgaria - and it inconvenient for me to visit them for a dyno tune , car is daily driven for 14 years) , i am not going after dyno results/power just for the silky smooth running m52 that i know from experience is there in the car

so m52b28sv ms41 , manual (97 sleeved block)

mods
- lighter flywheel (m20)
- stock airbox (no baffle) with KN
- 68.5mm TB
- m50b25 intake
- decat exhaust with Xpipe (as close to the runners as possible)

Uploading the last file i edited and also the readings from MS41 Quickflash knock table section (the car is detecting knock on euro 95 fuel)

in the file i have added fuel base table, corrected the rev drop (because of the flywheel), turned off catalytic functions, and corrected the vanos engagement

if anyone has any ideas , or advice if i am on the right track it would be appreciated

my approach is to drive the car for a day or two , read the knock tables and lambda corrections and where i see knock i add 0.01 fuel to those rpm/load cells

https://drive.google.com/file/d/1-P-nF5 ... drive_link ( the edit file that has generated the above results in the screenshot)

___________________________

So after that i took a look at the stock roms for options S962A and S961A

as latest idea i tried the fuel tables + ignition + idle control valve from s962a

my subjective feel is that the car does NOT hesitate ( low, mid, high , no matter the RPM) but as generally gives the impesion of driring a m50b25 engine - very linear, no feel of surging torque form 1500+ rpm - which in my opinion is key feature of m52sv engines

So next will try the S951A in the same way

The only thing I take away from this is that all the fuel in my country is knock inducing (with my stock ECU even with the stock intake) or something like that


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 Post subject: Re: ms41 m52b28 low rpm hesitation
PostPosted: Fri Oct 17, 2025 4:48 am 
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Joined: Thu Sep 04, 2025 7:19 am
Posts: 12
So still trying, car drives much better - have not checked it on dyno or with wide band but just my opinion. Sharing the latest file i made. Also the knock reading before editing it


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 Post subject: Re: ms41 m52b28 low rpm hesitation
PostPosted: Wed Oct 29, 2025 5:19 am 
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Joined: Thu Sep 04, 2025 7:19 am
Posts: 12
So still trying

Got to these Ign map and fuel map as good enough

________

added the partial file also, if someone wants to try it/dyno it/logg etc

i would not advise just flashing it, compare it with yours first - i am not "tuner", do not have AFR Wide band access to correctly do the fueling etc


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 Post subject: Re: ms41 m52b28 low rpm hesitation
PostPosted: Fri Nov 14, 2025 6:31 am 
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Newbie

Joined: Thu Sep 04, 2025 7:19 am
Posts: 12
well for non professional i think that is my limit, car drives smooth and nice, no hiccups or issues , sharing just if someone want a basic drivable setting (probably way, way of top power/optimal fueling) to go to the dyno


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 Post subject: Re: ms41 m52b28 low rpm hesitation
PostPosted: Wed Nov 19, 2025 1:21 pm 
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Joined: Mon Oct 20, 2025 3:03 pm
Posts: 7
hi ! any update ? are u still using this settings ? and why did u made some values ZERO .... like fuel enrichment


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 Post subject: Re: ms41 m52b28 low rpm hesitation
PostPosted: Fri Nov 21, 2025 3:51 am 
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Joined: Thu Sep 04, 2025 7:19 am
Posts: 12
yes still using it

the car is decat-ed so no fuel strategies for Catalist are present in my files (i have all of them off/0 ) i suppose you are asking about that


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