Deceleration

M52Drifter · **Joined:** Sun Sep 06, 2015 2:16 pm **Posts:** 144

Enabled wrote:

Well I also tried this on the 2.8 with 41.2 conversion (with a bunch of MS41.1 2.8 maps), and it did not do it as much.

The 41.2 has quicker fuel cut off, and shorter ECU cycles on fueling and ignition retard in comparison to 41.1.

After doing -30 deg ignition on decel it only does at best 3-6 quick crackles after 5000 rpm when letting off WOT. Nothing constant.

I see that the MS41.2 pulls fuel out quickly (greater percentage in fewer ecu cycles), which probably contributes to less rev-hang, and very quick RPM drops.
I like the quick rpm drops, so I don't know if we can have both.

I suppose I can put MS41.1 decel maps in as well. I kept those MS41.2 because I had liked the aggressive rev drops.

I'm tring to do the same on my car, MS41.0, I want a quick RPM drop, can you tell me which table I have to modify ? Fuel cut or fuel enleanment ?
Or i copy all the decel tables from the MS41.2 ?
Thanks for you help.

Enabled · **Posted:** Thu Apr 21, 2016 12:31 pm

M52Drifter wrote:

Enabled wrote:

Well I also tried this on the 2.8 with 41.2 conversion (with a bunch of MS41.1 2.8 maps), and it did not do it as much.

The 41.2 has quicker fuel cut off, and shorter ECU cycles on fueling and ignition retard in comparison to 41.1.

After doing -30 deg ignition on decel it only does at best 3-6 quick crackles after 5000 rpm when letting off WOT. Nothing constant.

I see that the MS41.2 pulls fuel out quickly (greater percentage in fewer ecu cycles), which probably contributes to less rev-hang, and very quick RPM drops.
I like the quick rpm drops, so I don't know if we can have both.

I suppose I can put MS41.1 decel maps in as well. I kept those MS41.2 because I had liked the aggressive rev drops.

I'm tring to do the same on my car, MS41.0, I want a quick RPM drop, can you tell me which table I have to modify ? Fuel cut or fuel enleanment ?
Or i copy all the decel tables from the MS41.2 ?
Thanks for you help.

Yes, use the MS41.2 decel maps as inspiration. Detection, ignition retard, fuel cut/enleanment, etc... they all work together for the quick rev drop.

I noticed just how much rev hang there is with MS41.1 when I converted completely to MS41.2. The US M3 decel (and accel) maps are nice and aggressive.

M52Drifter · **Joined:** Sun Sep 06, 2015 2:16 pm **Posts:** 144

Fuel enleanment maps and Ignition retard are greater on MS41.0 than MS41.2, if I keep them stock, would RPM drop faster do you think ?
I'll give a try with all the maps from the MS41.2, but I wanted your opinion.

M52Drifter · **Joined:** Sun Sep 06, 2015 2:16 pm **Posts:** 144

So I tried today a tune with all the deceleration maps from the MS41.2 on my euro 2.8, and there was a lot of problem, bad start, idle too low and not stable, very loud farts at the exhaust, it was not very good for the engine, after this I have checked on INPA, and lots of error including Vanos error... Well, It wasn't a good try for my contribution, decel maps and ignition retard were so different beetween MS41.2 and MS41.0.

So I decided to keep the decel maps stock from my MS41.0 and only play with the fast detection TPS, and it worked, RPM drops so much faster, I love it, sounds kind of like a Euro M3 now, I have the full exhaust though.

I have a video if you want to see, enjoy it =)

https://www.youtube.com/watch?v=68MfC_P ... e=youtu.be

busterhax · **Joined:** Wed Jan 22, 2014 6:54 pm **Posts:** 1773

Just keep playing around. That's the easiest way to learn and everyone's experience will be different.

Enabled · **Posted:** Sat Apr 23, 2016 9:43 pm

Did you try it on a warm engine?

M52Drifter · **Joined:** Sun Sep 06, 2015 2:16 pm **Posts:** 144

At first with the MS41.2 maps, no I tried with a cold engine but it was the same with warm engine.

d_munter · **Posted:** Tue Aug 16, 2016 12:24 pm

Did a pops on ms s50 also, which i have now.

beef68 · **Joined:** Wed Aug 27, 2014 7:23 pm **Posts:** 10

M52Drifter wrote:

So I tried today a tune with all the deceleration maps from the MS41.2 on my euro 2.8, and there was a lot of problem, bad start, idle too low and not stable, very loud farts at the exhaust, it was not very good for the engine, after this I have checked on INPA, and lots of error including Vanos error... Well, It wasn't a good try for my contribution, decel maps and ignition retard were so different beetween MS41.2 and MS41.0.

So I decided to keep the decel maps stock from my MS41.0 and only play with the fast detection TPS, and it worked, RPM drops so much faster, I love it, sounds kind of like a Euro M3 now, I have the full exhaust though.

I have a video if you want to see, enjoy it =)

https://www.youtube.com/watch?v=68MfC_P ... e=youtu.be

Sounds good

what values are you using to get this result, I haven't had any luck so far?

Matthijss · **Joined:** Thu Apr 09, 2015 1:31 pm **Posts:** 15

Looks like my o2 sensor exploded.
So be careful

busterhax · **Joined:** Wed Jan 22, 2014 6:54 pm **Posts:** 1773

lol what settings were you running?

Matthijss · **Joined:** Thu Apr 09, 2015 1:31 pm **Posts:** 15

busterhax wrote:

lol what settings were you running?

I think i was testing at -30 -40 degree not for sure. this was in 2015

Strange thing the o2 sensor was stil working so i did not know, when bought new ones and want to replace i saw this, scratching on my head W*F

busterhax · **Joined:** Wed Jan 22, 2014 6:54 pm **Posts:** 1773

Does it appear melted or does it look like something impacted it? It's weird one looks perfectly fine. Gotta be careful with egts

Enabled · **Posted:** Sat Nov 12, 2016 2:41 pm

Any way to make the exhaust burble for just a couple of seconds, instead of constant?

I tried looking through all the maps involved, and it seems it can be done by disabling fast Decreasing TPS? I haven't yet mentally sorted what and how the whole procedure happens, for each different condition.

busterhax · **Joined:** Wed Jan 22, 2014 6:54 pm **Posts:** 1773

Enabled wrote:

Any way to make the exhaust burble for just a couple of seconds, instead of constant?

I tried looking through all the maps involved, and it seems it can be done by disabling fast Decreasing TPS? I haven't yet mentally sorted what and how the whole procedure happens, for each different condition.

You can try ign retard decreasing tps - step size. Increasing this value will decrease the delay before ignition is pulled when in deceleration mode. It's possible you could get it to pull timing briefly before the injectors turn off when letting off the throttle.

RomRaider

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Deceleration

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