Launch control, CEL flash on knock, pops and bangs for 1993-1996 WRX

[pmugabi]

I'm releasing a modified ROM and Romraider definition for it. ROM is meant to be burnt onto a 27C1028 chip and put in the socket in the ECU. The ROM is modified with the following features:

1. Launch control with optional timing retard. Without timing retard I get 5psi of boost, with retard I get 12psi on a TD05 at 5k RPM.

2. Pops and bangs on overrun. Basically a make believe anti-lag. This is done by retarding timing only (to 0 degrees), no fuel is added so fuel economy should not suffer.

3. CEL flash on knock. It’s more like a flicker, but it’s visible. The check engine light is unfortunately not in the best of positions for viewing and is not too bright. I recommend fitting a bright red right connected to the CEL light in the middle of your field of view to make the most of this.

4. Engine shutoff on overheat. This cuts off the engine when the coolant temperature goes above a certain threshold. This is very useful when you realize that the stock temperature gauge does not seem to begin moving above center till about 110C and at this temperature the engine is most likely knocking like mad whenever on boost.

Parameters (under section Misc) in Romraider are:

Launch control speed: Vehicle speed above which launch control is disabled.

Launch control RPM: RPM above which launch control is enabled. If the engine fails to rev past this RPM even when the car is moving, your speedometer signal is not getting to the ECU. In that case disable launch control by raising this value to 9000.

Launch control retard RPM: RPM above which timing is retarded to 0 so as to give more boost with launch control. Set this to 500 rpm below the launch control RPM. To disable, raise to 9000

Overheat shutoff temp: Temperature above which fuel is cut off and engine is shut down. Fans kick in at 95C, so I set mine at 100C. With a good cooling system, the temperature should not get above 95C, so 100C is enough. If the car fails to start even when the engine is cold, you most likely have a dead coolant temp sensor causing the ECU to use a working temperate of 135C (if I remember correctly). In this case, set this value to 150C to disable this feature.

Pop and bang RPM: RPM above which timing is retarded to give pops and bangs. I use 2000 RPM for this. It will only pop well when you are driving hard, best way to hear it is to go down a slope in gear 2 or 3 at about 3000rpm.
Pop and bang TPS: TPS value above which timing is retarded to give pops and bangs. TPS *decreases* when the accelerator pedal is depressed. I use a value of 4.5V but depending on how your TPS is positioned, you might need to change the value to 4.3V or 4.2V to enable the pops and bangs.

If your car refuses to start when using this ROM, read the section above about Overheat shutoff temp

If your car refuses to rev past your launch control RPM, read the section above about launch control RPM.

If you get loud explosions out of your exhaust and/or very high boost when in launch control mode, you most likely have an exhaust leak between the engine and the turbo that is letting in air.

I have attached, the ROM, the notes I wrote when developing the modifications and an extract from the Romraider ECU defs. Put the extract at the end of your current Romraider def before the line that reads </roms>

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[jeffwrx]

Hi , i already have a chip installed in my ecu , would i still be able to use this as i want to get these features , would you be able to put this on the chip , as i have no way of reflashing the rom myslef , thanks

[pmugabi]

You would need to find someone local to you to copy the maps  from your chip, put the maps into the ROM I've provided and then burn it onto your chip.

I live in Uganda which is definitely very far from wherever you are.

Alternatively you can buy a programmer and EPROM eraser for less than $150 and be able to do this yourself. I bought the GQ-4X programmer and 27C1028 adapter from mcumall.com for about $120. A UV eraser should be about $20 from Ebay.

[matchstik]

Your site has been a great help to me. I'm going through the process to retune my EJ20G WRX right now and will likely use this map as a starting point because of all the added features!

One question though. I looked at your z5_launch_5k.bin map with just launch control added and RomRaider showed a LC RPM of 5000.

After adding the ECU defs extract, and opening the 20100811_Z4_LC_CEL_etc.bin map, the LC RPM shows up as 61650?

Is that correct?

[pmugabi]

The LC RPM should still show as 5000 with the new ROM. Possibly an error in the definition. I usually don't use Romraider to make changes to the LC settings so I had not tested the ECU def.

I've currently overhauled the whole code to make it cleaner and add some features
For example the overheat protection does not shut down the car but instead limits the engine to a set maximum RPM as well as flashing the engine light continously. The launch control is also effected by cutting off individual cylinders randomly instead of all at once so it sounds much better.

I think I'll have sorted out all the bugs by this weekend and I'll post an updated ROM and tested ECU definition next week.

[matchstik]

That sounds really awesome! I'd love to check it out.

[matchstik]

Ok so I did some more comparisons regarding the LC value. The ECU defs both point to 0xff21 for a storage address.

Now here's where my knowledge falls down. I opened up both roms in a hex editor (A previous LC only ROM that you posted, as well as the one in this thread), and looked at address ff21.

The value is different in each ROM, although I don't know how to interpret what that means...

If I paste the entire line on ff20 from the old ROM to the new one, the LC value in Romraider shows as 5000rpm again.

Did the location of the LC RPM change from the old rom to the new one?

Sorry for the newb questions. I've never dug this deep into a ROM before.

[pmugabi]

The notes that I took when doing this ROM give me the following info:

LC Speed at FFCA  (kph)
LC RPM at FFC8 (2 byte value, RPM *12.5 I seem to remember)
Retard RPM at FFC6 (2 byte value) - above this RPM, the timing will be retarded while in launch control mode to give more boost. The car will actually overboost if you keep the launch control engaged for more than about 2 seconds. The version I'll be working on this weekend will fix this by allowing you to set how much the timing is retarded, more retard = more boost.
Engine shutoff temperature at FFC5 (temp + 50)

[matchstik]

I'm starting to get the hang of understanding the instructions and locations, thanks!

Now that I can understand your notes (noob alert), I compared to your ecu_defs extract, and everything was called out correctly.

The problem was that I was using your old ecu_defs, so it was finding the old address for the LC RPM (ff21), and not using the revised locations in your ecu_defs extract.

Once I realized that, I got it sorted correctly and everything looks good. This is really ingenious stuff you have put into the ROM, I can't wait to see what you have next!

[rick9761]

Hi, this rom is very good have you managed to sort out the new version yet, looking forward to trying it very much, thank you

[pmugabi]

I had taken a short break from this since I acquired another car (a 1997 STi rally car) and have been busy re-wiring it to work with the 1993-1995 JECS ECU. I just finished that last weekend so I'll have a bit more time now. I did some bit of work on the ROM code but there are still a few bugs to work on. I'll try to get an update out by 19th December.

[pmugabi]

The new ROM is now done and attached. Changes are:
1. Overheat shutoff - limits RPM to 3k RPM instead of totally shutting off engine. Also flashes CEL continously when an overheat event is noticed.
2. Launch control strategy changed - sounds much better. From my limited testing it seems that the launch control RPM should be set about 700RPM below the desired one since there is a bit of an overshoot.

The top of notes.txt explains the various variables that can be changed.
Youtube video: http://www.youtube.com/watch?v=wj6E0H5cTec

[matchstik]

That's great Paul, thank you so much for sharing your work! I won't have a chance to try it out until the spring season, but I'll give you some feedback as soon as I can. Looks like some really neat additions.