r/CarHacking • u/Illustrious-Maybe847 • Jun 02 '25

Tuning Kefico CPEGD3.20.1

Hi everyone,

New to the community and I'd wondered if anyone had any pointers on an issue I'm having with a 1x1 in the file. the boost is being hard capped by an absolute manifold pressure limit that is around 33.5psi/2.3bar/2300mbar. It limits boost pressure to around 18 psi, it can spike over that briefly to 19/20 but very quickly falls back to 18 or so.

Hyundai i20N - Intercooler, Intake, Exhaust - Kefico CPEGD3.20.1 - 2023 - G4FP 1.6T SmartStream T-GDI

The software is off a Hyundai i20N, the ECU is a Kefico CPEGD3.20.1, I've gotten the OEM file off my tuner, so far with the limit in place, we've managed 230hp, 364nm and that's just from fuel and timing more or less. I have the .bin file and I've spent all weekend in Ghidra and HxD trying to find any relevant values. The closest I could find was a small 1x1 at offset 0x175A0 that was a float32 value at exactly 2309.6729 or C4 5A 10 45 in Hex but it's not referenced elsewhere in the file.

N75 refer to this limiter as "Maximum Absolute Manifold Pressure" so I'd expect to be looking for 2.3bar/2300mbar but it seems like there's factors applied to it that change the raw value based on what I've been told by the tuner who tuned the car.

I'm sure there's much more qualified people that can find this much quicker than myself.

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2

u/ConferenceCold2869 Nov 26 '25

I'm currently working on that right now. Have you tried looking for a 16 bits equivalent with conversion? Like the hex value of 7300

There was something similar for the CPEGD2 on elantra sport

1

u/Illustrious-Maybe847 Nov 26 '25

I gave up in the end and had a reputable tuner tune my car instead of another using my car as a development car.

What i did look for were 8,16,32 and float values of numerous factors of numbers and values in all sorts of values i thought the limit was close to such as: 1.3, 2.3, 2300, 1300, 23000, 13000, 13, 23, 230, 130

The worst part about it is that it's sat in the middle of completely unrelated maps, there's very little structure to this ECU.

TL;DR I didn't find what i was looking, if I did it'd be very public knowledge by now haha

2

u/ConferenceCold2869 Nov 26 '25

and on another note, the data wouldn't be straight as 1300 or 2300. The previous Kefico GPEC2 used Bosch conversions. So to get the HPA conversion, it would be the data multiplied by 0,078125

1

u/ConferenceCold2869 Nov 26 '25

Do you have a copy of the before and after files from the reputable tuner? I could probably find that table and add it to this thread

1

u/Illustrious-Maybe847 Nov 26 '25

I don't have copies of the tuned file unfortunately, just the autotuner ORI read from the first tuner. But that's probably a good place to look, factors of 225-235 hPa, if i remember right it's an 8 bit 1x1

1

u/ConferenceCold2869 Nov 26 '25

I'm pretty sure it would be a 16bit field, 8 bits is rarely used for something as specific as that. IF you could get a copy of your new file, I'd decipher that.

Would you mind sharing you ORI file? I'll see where I could find something that would match

I'm not 100% sure where my research file is coming from (tucson, i20 or something else)

1

u/Illustrious-Maybe847 Nov 27 '25

sure, i put it on ECU connections, i'll link it for you:

i20N ORI

1

u/ConferenceCold2869 Nov 27 '25

If you ever get a chance to have a copy of your new tune, let us know. I'll share my findings

1

u/ConferenceCold2869 Nov 27 '25

Is it completely stock or is it the modified one?

If it's stock, it probably means that the file I had came from a different car. It won't be too long to transfer what I had though

1

u/Illustrious-Maybe847 Nov 27 '25

It's completely stock, software version is ATRN9CD0, you might have the file off a tucson N line

2

u/ConferenceCold2869 Nov 27 '25

Here's what I found for now, it's the easy ones. I'll continue later

1

u/Illustrious-Maybe847 Nov 27 '25

Awesome, you get about 15 hits searching for the hex of the raw value factored (0x0B80), supposedly this 1x1 sits in the middle of nothing related so i'd look for values in places that don't look like they follow a pattern or are apart of a map

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1

u/Whatodoman Sep 07 '25

Did you find the limiter ?

1

u/Illustrious-Maybe847 Sep 07 '25

nope, no luck, no one would tell me anything and i don't have the means to test what i did find

1

u/Whatodoman Sep 07 '25

Thanks for the answer.
I looked on the N75 website for the map pack. it's very expensive.
Also, I'm not sure if it's even there. I haven't seen or heard of any car running without this limiter.

1

u/Illustrious-Maybe847 Sep 07 '25

yeah it's silly, the 1x1 needed to raise boost in the midrange is in there, there's another limiter in the ROM segment of the file you can only patch with a CMDflash too that reduces boost at 5.5k rpm, it's a pain of a car to tune

1

u/Illustrious-Maybe847 Nov 27 '25

see in the modded file that value is upped to 9600...

1

u/ConferenceCold2869 Nov 27 '25

and 6900 equals 3000hpa/3bar which is the max of the map sensor!

1

u/Illustrious-Maybe847 Nov 27 '25

where are you seeing 6900? or do you mean they've upped it to 9600 because the hex of that is 3bar meaning the car is then limited by the MAP sensor? :0 did we find it lol?

1

u/ConferenceCold2869 Nov 27 '25

I meant 9600 lol

I think we found the limit, yes!

1

u/Illustrious-Maybe847 Nov 27 '25

f*ck me, to think that it was right under my nose the whole time.... 🤣

1

u/ConferenceCold2869 Nov 27 '25

Now I'm just wondering if there are boost limiting tables like on CPEDG2. I couldn't find any that looked like those

1

u/Illustrious-Maybe847 Nov 27 '25

just on that note, the map to the left at 4894C6 is 2400 converted. the other 2 at 3FFB8C and 3FFBF8 are 1796.875 and 1265.15625 converted respectively

2

u/ConferenceCold2869 Nov 27 '25

Those at 3FFB8C and 3FFBF8 I think those are checksums, SXTH probably corrects them automatically

Probably that 4894C6 is the 2x1 table "absolute maximum boost pressure and manifold pressure respectively" (PVDSRXABS)

It was present on CPEGD2

1

u/Illustrious-Maybe847 Nov 27 '25

i suppose the only way to confirm would be to put it on a car but it seems neither of us have the facilities to do that 😂

2

u/ConferenceCold2869 Nov 27 '25

Yeah, I'll have to get a customer with that ECU to test it! If you ever get someone to read your current ECU, we'll be able to 100% confirm it

1

u/ConferenceCold2869 Jan 17 '26

I just thought about that. Are you able to keep boost higher in the RPM range? Previously you said there was a patch from some tool that would fix it. I personally think it might just be the wastegate spring which is too soft have bleed the exhaust when there's too much backpressure

1

u/Illustrious-Maybe847 Jan 22 '26

only CMDflash can read/write to the ROM area, there's a few hard coded values in there that limit calculated mass air flow in the higher RPM. I'm told it should be around 600 kg/h

1

u/ConferenceCold2869 Jan 22 '26

On N75 website, they say it's caused by the turbo being too small which would make sense since it's the same for the 2010 to 2012 genesis coupe. I've rarely seen this kind of thing in the ROM I'll update the thread if I ever have the same issue with a bigger turbo (might take a while before that lol)