Deceleration Fueling / Overrun RPM cutoff threshold tables

td-d · **Posted:** Thu May 10, 2012 9:18 am

Thanks to insistance by Andy (ElvenPointSevenFive), I am now certain that I've found the deceleration fueling RPM threshold fueling table for my Rom (and the 2010 USDM STI).

I actually found these some time back, but never got back to actually test driving these until Andy asked for them, which prompted me to scratch around the rom some more.

This 2D table determines (on an ECT x axis) at what RPM the injectors switch back on from coasting (i.e. full lean, and injector pulse width at zero). This would be useful to those with much larger injectors than stock that have a problem with stalling out as the vehicle comes to stop / idle.

I'll put up the routine and table as soon as I have a chance, but for now, here's the Ecuflash xml code. I'm pretty sure that I've got the the other related overrun fueling parameters of interest (delta throttle, overrun injector enrichment), but still need to dig through the code some more.

AZ1G202G

Code:

   <scaling name="OverRun Fueling " units="units" toexpr="x*0.1953125" frexpr="x/0.1953125" format="%.0f" min="0" max="255" inc="1" storagetype="uint16" endian="big"/>

   <table name="Overrun Fueling RPM Threshold" address="ca8d4" type="2D" level="1" scaling="OverRun Fueling ">
      <table name="X" address="c7ff4" type="X Axis" elements="16" scaling="DegreesF"/>
   </table>

AZ1G202I

Code:

   <scaling name="OverRun Fueling " units="units" toexpr="x*0.1953125" frexpr="x/0.1953125" format="%.0f" min="0" max="255" inc="1" storagetype="uint16" endian="big"/>

   <table name="Overrun Fueling" address="cba78" type="2D" level="1" scaling="Overun Fueling">
      <table name="Coolant Temp" address="c9110" type="X Axis" elements="16" scaling="DegreesF"/>
   </table>

Some guidance on finding these values in your rom

I still have to put up a run through the logic, but for those curious, the easiest way to find these is to go the the location of the Throttle Tip In Enrich Activation value in the rom, and usually above it you will see 2 values - for a number of the later roms I've looked at now, it is set to -17 for RPM Delta and 1400 for the injector enrichment (divided by 1000 gives ms).

e.g. AZ1G202G:

Code:

ROM:000C7EAC Overrun_Enrich_RPM_Delta_Activation:.float -17.0 ; DATA XREF: sub_33B6C+2Eo
ROM:000C7EAC                                         ; ROM:off_33DB0o
ROM:000C7EB0 Overrun_initial_enrichment?:.float 1400.0 ; DATA XREF: sub_33B6C+42o
ROM:000C7EB0                                         ; ROM:off_33DB8o
ROM:000C7EB4 ThrothTipInEnrichActivationThrottle:.float 1.0
ROM:000C7EB4                                         ; DATA XREF: Fun_TipinEnrichment+A4o
ROM:000C7EB4                                         ; ROM:off_33DFCo
ROM:000C7EB8 ThrothTipInEnrichActivation:.float 280.0 ; DATA XREF: Fun_TipinEnrichment+138o
ROM:000C7EB8                                         ; ROM:off_33E1Co
ROM:000C7EBC TipInEncrichCompensDectActivation:.float 1.0
ROM:000C7EBC                                         ; DATA XREF: Fun_TipinEnrichment+10Co
ROM:000C7EBC  

If you scroll down from that location, you will notice a sequence of 3 RPM values - normally starting with 1800 and ending with 4500 - those are the counters.

Code:

ROM:000C7EE4 Variable_flt_C7EE4:.float 1800.0        ; DATA XREF: sub_340EC+60o
ROM:000C7EE4                                         ; sub_340EC:off_34300o
ROM:000C7EE8 Variable_flt_C7EE8:.float 200.0         ; DATA XREF: sub_340EC+1AEo
ROM:000C7EE8                                         ; sub_340EC:off_3433Co
ROM:000C7EEC Variable_flt_C7EEC:.float 500.0         ; DATA XREF: sub_340EC+1C0o
ROM:000C7EEC                                         ; sub_340EC:off_34340o
ROM:000C7EF0 Variable_flt_C7EF0:.float 200.0         ; DATA XREF: sub_340EC+1CEo
ROM:000C7EF0                                         ; sub_340EC:off_34344o
ROM:000C7EF4 Variable_flt_C7EF4:.float 500.0         ; DATA XREF: sub_340EC+264o
ROM:000C7EF4                                         ; sub_344C4:off_34588o
ROM:000C7EF8 Variable_flt_C7EF8:.float 100.0         ; DATA XREF: sub_340EC+276o
ROM:000C7EF8                                         ; sub_344C4:off_3458Co
ROM:000C7EFC Variable_flt_C7EFC:.float 500.0         ; DATA XREF: sub_340EC+282o
ROM:000C7EFC                                         ; sub_344C4:off_34590o
ROM:000C7F00 Over_Fueling_RPM_Range_1:.float 1800.0  ; DATA XREF: sub_344C4:loc_3452Eo
ROM:000C7F00                                         ; sub_344C4:off_345E8o
ROM:000C7F04 Over_Fueling_RPM_Range_2:.float 3200.0  ; DATA XREF: sub_344C4:loc_3453Ao
ROM:000C7F04                                         ; sub_344C4:off_345ECo
ROM:000C7F08 Over_Fueling_RPM_Range_3:.float 4500.0  ; DATA XREF: sub_344C4:loc_34546o 

Above the counters a couple of values - in my rom 500 and 200 (see above) - follow the Xref from one of these back to the data offset location, you will see that there is a 2D table - this is the overrun fueling resume table.

Code:

ROM:00034330 off_34330:      .data.l Table_Overun_Fueling_RPM_Resume
ROM:00034330                                         ; DATA XREF: sub_340EC+15Cr
ROM:00034334 off_34334:      .data.l Fun_GetMapValue2D_8B_16B_Float
ROM:00034334                                         ; DATA XREF: sub_340EC+15Er
ROM:00034338 off_34338:      .data.l Variable_word_C7750 ; DATA XREF: sub_340EC+196r
ROM:0003433C off_3433C:      .data.l Variable_flt_C7EE8 ; DATA XREF: sub_340EC+1AEr
ROM:00034340 off_34340:      .data.l Variable_flt_C7EEC ; DATA XREF: sub_340EC+1C0r
ROM:00034344 off_34344:      .data.l Variable_flt_C7EF0 ; DATA XREF: sub_340EC+1CEr

To verify, the multiplier for the tables should be 0.1953125 and the offset 0.

Code:

ROM:00088DC8 Table_Overun_Fueling_RPM_Resume:.data.w h'10 ; DATA XREF: sub_340EC+15Co
ROM:00088DC8                                         ; sub_340EC:off_34330o
ROM:00088DC8                                         ; 16 Lignes
ROM:00088DC8                                         ; 16 Byts
ROM:00088DCA                 .data.w h'800
ROM:00088DCC                 .data.l Table_CoolantTemperature_YAxis
ROM:00088DD0                 .data.l Overun_Fueling_RPM_Resume
ROM:00088DD4                 .float 0.1953125        ; Engine speed
ROM:00088DD8                 .float 0.0

td-d · **Posted:** Sun Jun 03, 2012 12:40 pm

Ok - I've found the other three parameters associated with overrun fueling.

For AZ1G202G:

Code:

   <table name="Overrun_Enrich_RPM_Delta_Activation" address="C7EAC" type="1D" level="1" scaling="rawecuvalue"/>

   <table name="Overrun_initial_enrichment" address="C7EB0" type="1D" level="1" scaling="ms"/>

and the overrun RPM threshold for the counters that determine when the injectors are cut:

Code:

   <table name="Overrun_Fueling_Cut_Counter_RPM_Threshold" address="C7F00" type="2D" level="1" scaling="RPM">
      <table name="RPM" type="Static X Axis" elements="3">
         <data>Low</data>
         <data>Med</data>
         <data>High</data>
      </table>
   </table>

for AZ1g202I, the addresses are:

Code:

   <table name="Overrun_Enrich_RPM_Delta_Activation" address="C8FFC" type="1D" level="1" scaling="rawecuvalue"/>

   <table name="Overrun_initial_enrichment" address="C9000" type="1D" level="1" scaling="ms"/>

and the overrun RPM threshold for the counters that determine when the injectors are cut:

Code:

   <table name="Overrun_Fueling_Cut_Counter_RPM_Threshold" address="C9050" type="2D" level="1" scaling="RPM">
      <table name="RPM" type="Static X Axis" elements="3">
         <data>Low</data>
         <data>Med</data>
         <data>High</data>
      </table>
   </table>

dj-phoenixx · **Posted:** Tue Jul 17, 2012 3:20 pm

Hi,
It is possible that the overrun fuel cut with my bov has to do? Because if I'm opened it. And then cruise or fully kick the gas like an WOT and then its idling speed should reach back, he simply goes out.

Marcel

td-d · **Posted:** Tue Jul 17, 2012 4:34 pm

Are you running larger injectors? If you are, it might make sense to have the injectors switch back on earlier.

dj-phoenixx · **Posted:** Wed Jul 18, 2012 3:47 am

Hi,
no my fuel system is stock.

Marcel

td-d · **Posted:** Wed Jul 18, 2012 4:50 am

I don't think this would be the right approach to take then.

dj-phoenixx · **Posted:** Wed Jul 18, 2012 1:39 pm

ok. what is in your opinion the better way to solve this problem?

td-d · **Posted:** Wed Jul 18, 2012 2:01 pm

Someone with more mechanical experience will surely chime in - what I can tell you is that tuning BOVs on MAF fueling is a real pain in the ass. On SD, no problem.

Sasha_A80 · **Posted:** Wed Jul 18, 2012 2:15 pm

I really stop tuning till BOV deleted and a stock bypass restored.

dj-phoenixx · **Posted:** Wed Jul 18, 2012 2:41 pm

thx for answear. hard to hear that i must change to sd. I'm really in worry with it.

td-d · **Posted:** Wed Jul 18, 2012 2:44 pm

Sasha_A80 wrote:

I really stop tuning till BOV deleted and a stock bypass restored.

Yup, in a nutshell. It's more headache than it's worth.

Merp · **Joined:** Thu Jul 23, 2009 1:46 pm **Posts:** 863

td-d wrote:

Someone with more mechanical experience will surely chime in - what I can tell you is that tuning BOVs on MAF fueling is a real pain in the ass. On SD, no problem.

This.

BOV + MAF = FAIL

Sasha_A80 · **Posted:** Sun Jul 22, 2012 7:55 am

Too many entries found for MT ROM A8DH100F:
(8 here and 7 ones for 512KB ROMs )

It looks like those are NeutralPositionSwitch\ClutchSwitch\Gear dependent.

Probably the last six are just IdleSpeed vs Coolant with AirCon On\Off and AT\MT config ??

ROM:000858F0 decel_fuel_restore_rpm_vs_coolant_858F0:.data.b 0, h'10, 8, 0
ROM:000858F0 ; DATA XREF: decel_rpm_vs_coolant_sub_32F78:off_331ECo
ROM:000858F4 .data.l coolant_flt_C7A0C
ROM:000858F8 .data.l decel_rpm_word_C8B48
ROM:000858FC .float 1.953125e-1
ROM:00085900 .float 0.0

ROM:00085924 decel_fuel_restore_rpm_vs_coolant_85924:.data.b 0, h'10, 8, 0
ROM:00085924 ; DATA XREF: sub_35176:off_351C0o
ROM:00085928 .data.l coolant_flt_C7A0C
ROM:0008592C .data.l decel_rpm_word_C8BC2
ROM:00085930 .float 1.953125e-1
ROM:00085934 .float 0.0

ROM:000866B4 _1_1_decel_fuel_restore_rpm_vs_coolant_866B4:.data.b 0, h'10, 8, 0
ROM:000866B4 ; DATA XREF: idle_fuel_cut_sub_423F8:off_426A8o
ROM:000866B4 ; ROM:off_43F30o
ROM:000866B8 .data.l coolant_flt_CC154
ROM:000866BC .data.l decel_fuel_restore_rpm_word_CC530
ROM:000866C0 .float 1.953125e-1
ROM:000866C4 .float 0.0

ROM:000866C8 _0_1_decel_fuel_restore_rpm_vs_coolant_866C8:.data.b 0, h'10, 8, 0
ROM:000866C8 ; DATA XREF: idle_fuel_cut_sub_423F8:off_426ACo
ROM:000866C8 ; ROM:off_43F34o
ROM:000866CC .data.l coolant_flt_CC154
ROM:000866D0 .data.l decel_fuel_restore_word_CC550
ROM:000866D4 .float 1.953125e-1
ROM:000866D8 .float 0.0

ROM:000866DC _1_2_decel_fuel_restore_rpm_vs_coolant_866DC:.data.b 0, h'10, 8, 0
ROM:000866DC ; DATA XREF: idle_fuel_cut_sub_423F8:off_426B0o
ROM:000866E0 .data.l coolant_flt_CC154
ROM:000866E4 .data.l decel_fuel_restore_rpm_word_CC570
ROM:000866E8 .float 1.953125e-1
ROM:000866EC .float 0.0

ROM:000866F0 _0_2_decel_fuel_restore_rpm_vs_coolant_866F0:.data.b 0, h'10, 8, 0
ROM:000866F0 ; DATA XREF: idle_fuel_cut_sub_423F8:off_426B4o
ROM:000866F4 .data.l coolant_flt_CC154
ROM:000866F8 .data.l decel_fuel_restore_rpm_word_CC590
ROM:000866FC .float 1.953125e-1
ROM:00086700 .float 0.0

ROM:00086704 _1_4_decel_fuel_restore_rpm_vs_coolant_86704:.data.b 0, h'10, 8, 0
ROM:00086704 ; DATA XREF: idle_fuel_cut_sub_423F8:off_426B8o
ROM:00086708 .data.l coolant_flt_CC154
ROM:0008670C .data.l decel_fuel_restore_rpm_word_CC5B0
ROM:00086710 .float 1.953125e-1
ROM:00086714 .float 0.0

ROM:00086718 _0_4_decel_fuel_restore_rpm_vs_coolant_86718:.data.b 0, h'10, 8, 0
ROM:00086718 ; DATA XREF: ROM:off_428C8o
ROM:0008671C .data.l coolant_flt_CC154
ROM:00086720 .data.l decel_fuel_restore_rpm_word_CC5D0
ROM:00086724 .float 1.953125e-1
ROM:00086728 .float 0.0

td-d · **Posted:** Sun Jul 22, 2012 10:38 am

For A8DH100F, table location is:

Code:

00858F0 word_858F0:     .data.w h'10            ; DATA XREF: sub_32F78:loc_33120o
ROM:000858F0                                         ; sub_32F78:off_331ECo
ROM:000858F2                 .data.w h'800
ROM:000858F4                 .data.l flt_C7A0C
ROM:000858F8                 .data.l h'C8B48
ROM:000858FC                 .float 0.1953125
ROM:00085900                 .float 0.0

Look for the RPM delta and initial enrichment sequence:

Code:

00C781C flt_C781C:      .float -17.0            ; DATA XREF: sub_32ACA+46o
ROM:000C781C                                         ; ROM:off_32D08o
ROM:000C7820 flt_C7820:      .float 1400.0           ; DATA XREF: sub_32ACA+66o
ROM:000C7820                                         ; ROM:off_32D14o

Below it (but above the RPM rev limit), you'll find a couple of references values Xref's which usually has a -50 in it:

Code:

ROM:000C7830 flt_C7830:      .float 200.0            ; DATA XREF: sub_32F78:loc_330CCo
ROM:000C7830                                         ; sub_32F78:off_331D4o
ROM:000C7834 flt_C7834:      .float 15.0             ; DATA XREF: sub_32F78:loc_330D2o
ROM:000C7834                                         ; sub_32F78:off_331D8o
ROM:000C7838 flt_C7838:      .float 600.0            ; DATA XREF: sub_32F78+164o
ROM:000C7838                                         ; sub_32F78:off_331DCo
ROM:000C783C flt_C783C:      .float -50.0            ; DATA XREF: sub_32F78:loc_330E2o
ROM:000C783C                                         ; sub_32F78:off_331E0o
ROM:000C7840 flt_C7840:      .float 1000.0           ; DATA XREF: sub_32F78+192o
ROM:000C7840                                         ; sub_32F78:off_331E4o
ROM:000C7844 flt_C7844:      .float 0.0              ; DATA XREF: sub_32F78+1A2o
ROM:000C7844                                         ; sub_32F78:off_331E8

Follow these references back to the data location, and you'll find the table:

Code:

ROM:000331D0 dword_331D0:    .data.l h'FFFF          ; DATA XREF: sub_32F78+116r
ROM:000331D0                                         ; sub_32F78+1D8r
ROM:000331D4 off_331D4:      .data.l flt_C7830       ; DATA XREF: sub_32F78:loc_330CCr
ROM:000331D8 off_331D8:      .data.l flt_C7834       ; DATA XREF: sub_32F78:loc_330D2r
ROM:000331DC off_331DC:      .data.l flt_C7838       ; DATA XREF: sub_32F78+164r
ROM:000331E0 off_331E0:      .data.l flt_C783C       ; DATA XREF: sub_32F78:loc_330E2r
ROM:000331E4 off_331E4:      .data.l flt_C7840       ; DATA XREF: sub_32F78+192r
ROM:000331E8 off_331E8:      .data.l flt_C7844       ; DATA XREF: sub_32F78+1A2r
ROM:000331EC off_331EC:      .data.l Table_Overrun_Fuel_Resume_RPM
ROM:000331EC                                         ; DATA XREF: sub_32F78:loc_33120r
ROM:000331F0 off_331F0:      .data.l Fun_GetMapValue2D_8B_16B_Float
ROM:000331F0                                         ; DATA XREF: sub_32F78+1ACr
ROM:000331F4 off_331F4:      .data.l unk_FFFF7274    ; DATA XREF: sub_32F78+1B4r
ROM:000331F8 off_331F8:      .data.l unk_FFFF7278    ; DATA XREF: sub_32F78+1B8r
ROM:000331FC off_331FC:      .data.l unk_FFFF726C    ; DATA XREF: sub_32F78+1BAr
ROM:00033200 off_33200:      .data.l word_C72C6      ; DATA XREF: sub_32F78+1F2r

The counter RPM threshold values also sit just below these values:

Code:

ROM:000C7868 Overrun_Fueling_Cut_Counter_RPM_Threshold:.float 1700.0
ROM:000C7868                                         ; DATA XREF: sub_334B4:loc_334FAo
ROM:000C7868                                         ; sub_3361E:off_336ECo
ROM:000C786C flt_C786C:      .float 2500.0           ; DATA XREF: sub_334B4:loc_33508o
ROM:000C786C                                         ; sub_3361E:off_336F0o
ROM:000C7870 flt_C7870:      .float 3500.0           ; DATA XREF: sub_334B4:loc_33516o
ROM:000C7870                                         ; sub_3361E:off_336F4o
ROM:000C7874 Rev_Limit_Fuel_Cut:.float 6700.0        ; DATA XREF: ROM:000338A0o
ROM:000C7874                                         ; ROM:off_3391Co
ROM:000C7878 flt_C7878:      .float 6650.0           ; DATA XREF: ROM:loc_338B4o
ROM:000C7878                                         ; ROM:off_33920o

Sasha_A80 · **Posted:** Sun Jul 22, 2012 12:17 pm

Thanks a lot.

But I still do not understand the meaning of the second table found.
It looks like another branch for fuel overrun threshold tables.

There was no this altenative table within 512KB ROMs I had observed.

The last six are definately IdleRPM tables.

RomRaider

Deceleration Fueling / Overrun RPM cutoff threshold tables

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