ECCS ROM Fuel Control

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RB20DE/T : Hi Octane mixture revision MAP (adr:7d00-7DFF)
RB20DE/T : Regular mixture revision MAP (adr:7500-75FF)
RB30E/T: Regular mixture revision MAP only (adr: 3D00-3DFF) with 16x16 map

The data above the 80h on the MAP (the Ktmr territory) it is called the feedback territory, it is the C0h offset. For example in the case of the C7h it becomes with 7, and in the case of the BFh minus it becomes a revision and becomes -1. This territory occurs at the time of accelerator off and, being kind not to read only at the partial time, increases for most normal data.

The data on this MAP (the Kmr & the Ktmr) contain various revisions determine how the effective injection quantity (the Te) is decided.

Effective injection quantity (Te) =
Basic injection quantity (Tp) x
various correction coefficients (CO) x
air/fuel ratio feedback correction coefficient (A)

The basic injection quantity is decided by the basic injection quantity (the Tp) and the engine rpm which is detected from the inhalation air quantity (AFM) and the crank angular sensor (CAS). Detected from air flow, this basic injection quantity (the Tp) using the air/fuel ratio decided is called base air/fuel ratio. Normally, in order for base air/fuel ratio to be near 14.7, the basic injection quantity (the Tp) must be calculated. To understand it easier, think that when the data coming from the MAP everything 0 and reading wherever on the MAP,means that it designates air/fuel ratio as 14.7.

It seems the ECU can decide the Tp on the basis of the value which is obtained with the following arithmetic expression.

Air flow voltage with the VQ map and the AD the value ×
K constant which is converted /
was calculated on the basis of rpm value

For example the following correction on the MAP of 26h with the Tp lattice value 70h when

1. First the basic injection quantity (the Tp) we find
112d (Tp lattice value 70h) × 0.125msec (injection time constant) =14msec

2. Next from the correction of the MAP mixture correction coefficient (CO) we find
Data (H) > in case of 80h (data (D) -64) /128
The data (H) <80h??? (data(d)+128)/128 being
MAP correction 26h <80h???(26h?38d+128)/128=1.296875

It becomes a more indicative injection quantity than the numerical value of above-mentioned two
(the Te)=14msec (the Tp) the ×1.296875 (CO) =18.15625msec

In this case the injection time of approximately 18.156msec is set. This injection time is, when other various revisions do apply (including air/fuel ratio feedback correction coefficient (A)), and becomes contingent standard of injection time.

Various correction coefficients (CO)
With the mixture revision MAP data increasing in quantity the time of cold (the Ktw) revision is increasing when the flood time is warm (the Kh). When starting and increasing in quantity revision, after starting (the Kas) et cetera adds 1 to various revision numerical values in addition to revision.

Air/fuel ratio feedback correction coefficient (A)
We have come close to getting the revision based on the air/fuel ratio to theoretical air/fuel ratio. This is done in order to get the catalytic converter transformation efficiency of the rhodium effectively.

Air/fuel ratio arithmetic expression
With this standard it is possible to calculate air/fuel ratio from the data on the MAP.
Data (H) > in case of 80h 14.7/ ((data (D) -64) /128)
The data (H) <80h??? 14.7/((data(d)+128)/128)
* this is the arithmetic expression based on when the air/fuel ratio becomes 14.7

Calculation of injector opened valve ratio
It can also calculate the injector opened valve ratio from the data on the MAP.

For example at the time of the 4000rpm correction on the MAP the 26h has become with the Tp lattice value 70h when

1. The basic injection quantity (the Tp) we find
112d (Tp lattice value 70h) ×0.125msec (injection time constant) =14 msec

2. MAP mixture correction coefficient (CO) we find
Data (H) > in case of 80h (data (D) -64) /128
The data (H) <80h??? (data(d)+128)/128 is being
MAP correction 26h <80h???(26h?38d+128)/128=1.296875
this is the same as the arthitmetic expression before

3. Injector opened valve ratio we find
Opened valve ratio = (14msec×1.296875) / (time factor 600 (4000rpm/ factor 2)) =60.52%

When this numerical value is used with the injector and air flow et cetera, and the K constant and the VQ map et cetera are modified, note there is a being a possibility of slipping largely due to the actual opened valve ratio being modified

The K constant is when the injector and air flow are exchanged, must modify numerical value, be sure. So, even that way almost until now to adjust to the burning pitch of sort it can do the numerical value on the map with doing.

The K constant is when the injector and air flow information are exchanged through a numerical value. To adjust the burning pitch you can modify this numerical based on the Tp map

The capacity comparative amount that can measure air flow increases the time of air flow exchange
(450ps/270ps=1.67)
At the time of injector exchange it is inversely proportional to the emission quantitative ratio of that injector
(260cc/370cc=0.70)

The R32-RB20DET normal K constant 0101h -> 257d×1.67×0.70=300d -> which designates the 012Ch as standard with the description above and it has reached it present value with the calculated value and using the O2 monitor as a reference.

(The A/F of the idle section when normally 14.1 rank (making the data C5h) modifies the part in the C5h and if after the sufficient warming up, setting to the K constant to where A/F value reaches 14.1 mark, the ROM will cut the O2 feed for good reason. After that control with the data of the MAP is fine then, it is the OK.
Presently we have set to the 0136h.

The "K constant" which is a value easily found within ROM EDITOR under the Global tab (its called K required number). It is the key to a hell of a lot of things. It is a constant value that can be adjusted to suit various changes. If you were to decrease or increase its value, its a surefire way to quicky enrichen or lean' your fuel maps. But where this value really comes into play, is when you do things like:

To install a RB20DET AFM in a Silvia, which is known to flow around 310ps (knowing what it flows and knowing that the value is accurate, is IMPORTANT!). In order to make the car run with this AFM, you will need to do TWO things..

The most obvious one to most people, is changing the VQ Map. A basic summary of how things work, is the VQ map’s values are proportional to the injector pulses, and the base value that it works with is the “K required number” that is in HEX that you’ll find in the Global tab in the ROM Editor program… how to work out what value to change that to is relatively simple..

Take the current value that’s there.. in the case of the CA its 00B7 (.. which is B7 in hex which is 183.. if you haven’t played with hex before, just pull up the windows calculator and click on View and select scientific mode.. then click the Hex check option thing and type in the hex value, then click decimal and there’s its actual decimal value)..

Alrighty.. so say.. B7 is the value in mine, and that’s suited for an AFM with a resolution up to 190ps (stock CA AFM).. in your case.. the SR20 AFM has a resolution up to 210ps.. what you have to work out is the new “K required number” to suit your new AFM.. my new afm was an RB20 unit of 310ps.. so this is how I worked it out..

Current AFM = 190
Current AFM K required number = 183
New AFM = 310
New AFM K required number = ???

So.. you gotto work it out… bit like this..
(just use windows calculator and when open, click View and select Scientific)

183 / 0.612903 = 298.579057
Then click on the Hex option in the calculator while that answer is still in it.. and I have the value 12A.

The Rom Editor program likes this entered in as 4 digits.. so the new value to put in there is 012A (zero, one, two, A)

Note: I've had troubles with my car starting when cold, but otherwise it runs fine, I'll let people know what the problem is when I find out.. if anyone has any ideas, let me know.

So in calculator, click Hex, type in 12A, then click decimal, and click multiply and enter 0.849.

Click back to hex, and your value is FD, enter that in ROM EDITOR as 00FD (zero, zero, F, D).

Also, I used the correction of 0.849 to all the values in the 'boost' section along the bottom of the fuel maps. You will find that once you adjust all those values, and then click Setup - Engine Specification setup, and adjust the Injector Blas-off quantity to the injector size that you are now using, all the values will come back to normal compared to the original map with uncorrected values and standard injector size spec).

Invalid injection time of the 370cc injector of the RB25DET with the 260cc injector is 35h and RB20DET it is 4Ch. Presently advancing setting, as 35h it increases.

TP lower limit value table
(adr:7e80-7E8F)
RB30E/T: 3e80?
Rpm (load?)
Every item in the table which decides the lower limit value of the basic injection quantity.

7e80: 08 08 08 08 08 08 08 08 08 08 08 08 08 08 08 08 seichan31z
7e80: 08 08 08 08 08 08 08 08 08 08 08 08 08 08 08 08 RB20DET
7e80: 07 07 07 07 07 07 07 07 07 07 07 07 07 07 07 07 RB25DET
3e80: 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B 0B RB30E/T ?

TP upper limit table
(adr:7e90-7E9F)
RB30E/T: 3e90?
This way it is possible to take burning pitch roughly, by modifying this with the table decideing the upper limit of the basic injection quantity.
7e90: 25 25 40 50 60 FF FF FF FF FF FF FF FF FF FF FF seichan31z
7e90: B8 B8 70 68 68 68 68 6a 68 68 68 6c 80 80 80 80 RB20DET
7e90: 25 25 38 40 40 FF FF FF FF FF FF FF FF FF FF FF RB25DET
3e90: 74 74 74 74 78 78 7C 80 80 84 84 88 88 8C 90 94 RB30E/T ?

The data displayed in a hex editor when viewing the fuel/igniton maps is a bit confusing if you're not using the 3D graph editing function.. if you insist on working with the numbers, here's some more information.

The formula to achieve the correction factor is
if DATA > 128 then Factor = (DATA - 64) / 128 else Factor = (DATA + 128) / 128

* Basic fuel injection = air flow output (curved line) -> VQMAP (straight line) x K constant XXDIV rpm + various revisions (MAP and the like)

* Simultaneous injection mode = effective injection quantitative + invalid injection quantitative voltage revision

* Sequential mode = effective injection quantitative x 2 + invalid injection quantitative voltage revisions

* Effective injection quantitative = basic injection quantitative x various correction coefficient x air/fuel ratio feedback correction coefficients

* Basic injection quantitative = air flow output (0. 08v - 5. 12v 0. 08v it cuts) AD converting

* Various correction coefficient = 1 + air/fuel ratio revision map + water temperature correction coefficient + starting correction coefficients