The parameters of the launch control with stock turbo kkk7000.

[vwnut8392]

I don't use the clutch switch (drive V8 automatic)
Will mod my V8 file for ign cut during shifting

thats very interesting! if you do that take some video, i'd like to see spark cut during shift on a V8 automatic.



personally i dont feel that a fuel cut flat shift is a useful when compared to a spark cut flat shift. to me on turbo car the point of spark cut flat shift is so that the car backfires causing the turbo to keep spooled between shifts. on my car it never goes below 20psi when i use spark cut flat shift. the fuel cut would help with slightly faster shift by unloading the engine for a split second but it not nearly as useful as spark cut which unloads the engine plus keeps the turbo spooled up. i think this is why PRJ never made a fuel cut flat shift.

[Acki]

I want backfire during shifting, that's all :-D No other reason.

[jonn48]

Launch control works with a bigturbo file. I just took it and set it up for stock.

[tekstil]

Launch control works with a bigturbo file. I just took it and set it up for stock.

Are you talking about Fuel cut LC or Spark cut LC?

[jonn48]

Are you talking about Fuel cut LC or Spark cut LC?

Spark cut LC.

[Acki]

I don't use the clutch switch (drive V8 automatic)
Will mod my V8 file for ign cut during shifting

Have my mod running. Black smoke and a lambda controller restart... no flames yet

[Acki]

RAM_25.1 is stock fuel cut - to make things easier

[-ice-]

Hi,

short summary, because I needed this again...

fuelcut launch-control (or more precise the code-part to cut fuel at certain RPM in launch control mode) is not activated by default in PRJ-MOD.


There are two versions of the code, which acutally trigger just(!) the fuel cut:

1.
https://www.s2forum.com/forum/techni...48#post2047048
--> this is included in the PRJ-MOD hex files but not used.


2.
https://www.s2forum.com/forum/techni...71#post2047371
--> this does basically same thing, but is better understandable.

I tested variant 2. and it works fine. With both variants, the stock code for cutting fuel is used but extended with a vehicle speed check and overhanding the respective fuel cutting RPM-threshold (two bytes in X-RAM).

If you translate variant 2. in pseudo C-code you can easily understand (out of my mind, no warranty....)

void fuel_cut_launch_control() // will be called from 0x399f
{
    unsigned char vehicle_speed;
    unsigned char temp_r2;
    unsigned char temp_r3;

    P2 = 1;

    vehicle_speed = XRAM[0x70];

    P2 = 4;

    if (vehicle_speed < 3) // Assumption car is stationary if vehicle Speed < 3;
    {
       DPTR = 0x8600;
    }

   temp_r2 = CODEMEM[860A] // @A+DPTR --> 8600 + 0x0A
   temp_r3 = CODEMEM[860B] // @A+DPTR --> 8600 + 0x0B


   XRAM[0x0A] = temp_r2; //copy to XRAM Location for fuel cut
   XRAM[0x0B] = temp_r3; //I understand both as low and high Byte...


   if (vehicle_speed < 3) // in ASM this check isn't ececuted twice but still indicated trough the carry flag
   {
       DPTR = 0x838B;
    }

    jump_to_code_39AB()
}

In simple words: If the vehicle is stationary, we give him our RPM threshold (stored at 0x860A) for cutting fuel. If not stationary, ECU will use default RPM thresholds.

As always, I will not give any bins. If you want to implement Variant 2. you can copy the hex op codes (39 bytes) to a free location at the end of the bin and then jump to it with an LJUMP. As you can see it automatically jumps back to 0x39AB with the last statement.


Now my next question is, why I don't see ignition reatarding in the logging (IGN_out or Requested IGN) altough something happenes at this threshold "Launch control IGN retard RPM"

Does anyone know?

BR

[-ice-]

I think I played enough for today...

1. The "motorsport subroutine" at 0x8610 ist definitely called also in the stock PRJ bin-file (stock_AANABY_27c512.bin). Thats a fact. If you alter f.e. parameter "Launch control IGN retard RPM" (which lays with its adress 0x8625 exactly in this block and is used within a compare), this has an effect.

The "motorsport subroutine" has a return at the end. So I would expect it is called somewhere in the code with lcall 8610 (op code 12 86 10). And that is the case. If you search this with a hex editor, you can find the point, where the motorsport subroutine is actually called.


2. What does the "Launch control IGN angle" mean exactly? what do f.e. the 8,25° degrees mean? The ignition angle is usually RPM dependend and we want to retard it, to get more gas in the exhaust- so good so far. But how does this actually work? Is it substracted from the base ignition angle in direction of late? Is 8 degrees good, safe or whatever? Can we burn our valves with too late timing?
How does it affect the amount of boost built up and is it worth tuning?

From the wiki:

• Launch control IGN retard RPM. If RPM is above this preset, ignition is forced to a static angle and knock control is switched off.
• Launch control IGN angle. This is the ignition angle that ignition is forced to. The values are ATDC. Increase this to build more boost, reduce it to build less boost. High boost off the line is not terribly useful, there should be enough boost that the car doesn't bog, usually 1 bar is plenty.

Should be a static angle. really?

BR