$EE EVAP system tuning

hey guys, hope you can help me with this one. i have an annoying problem with an LT1 $EE

i've deleted the CCP system completely, and found an issue that i can't seem to get around trying to tune it out

first off, the coolant temp to enable CCP cannot be used to disable the system, as it shares some kind of boundary with CL modes. i presume this is a 'feature' so the lack of a horrifying unmetered air leak that the CCP sends through the throttle body wont taint the regular BLMs.

although it is possible to enter closed loop before the CCP coolant enable temp is reached, this limits all normal driving activity (non decel/idle) to BLM cell 18, so effectively, raising the temp out of range limits you to cell 18, dropping all 'normal' blm cells.

one cool thing is, dropping the CCP enable temp to below freezing seems to push it into regular block learn mode almost instantly after CL is entered.

i have also noticed (only through datalogging so far) that there are obviously some hidden correction factors against CCP duty cycle. i can only assume there's both airflow and MAP corrrections.

as the purge duty cycle increases, my AFR goes to shit, and i get nasty part throttle BLM splits.

i have attempted to correct for the lack of unmetered air and fuel fumes with maf calibration, somewhere in between 15 and 20% maf scaling up until 90afgs or so to be close

...now here's the kicker; i think someone already found a hack to disable it properly, including any calibration factors. from the manual for LT1EDIT Expert:
The Expert Editor includes this function menu, it is not in the Standard version of the editor. It allows you to toggle thefollowing PCM functions On or Off.

Transient Fuel
This disables the Charcoal Cannister air purge.

i guess the easy way would be if anyone happens to have a copy of LT1EDIT that would be willing to send me two bins to diff; i would be so happy to figure the hack out myself...

starting to think i'm going to have to brush up on my assembly to solve this.. i've only ever done motorola risc assembly, this 68k shit looks a bit different for sure

I was hoping someone had an answer for you... but we do have some dissasemblies avalable that may have it or be easier start to find it?

http://www.gearhead-efi.com/Fuel-Inj...ull=1#post2423

i'm definitely working with those, unfortunately nobody has located any evap system stuff in there yet, so it's all on me.

i can't seem to even locate a memory address for the CCP duty cycle, which i assume would be the best place to start, since the CCP actuator routine must reference this location, as well as whatever the hell compensates the AFR for it being open.

still holding out hope an lt1edit user will get ahold of me so i can just diff the thing....

You sure all these problems are from CCP? I've done transplants of the LT1 motor and not had issues like this? Now the AIR Pump dose cause some issues if not disabled...

yep. i'm sure. the maf calculations on the low end have been totally whacked out since i deleted it, and if i make a fake CCP system and re-attach the solenoid, it's right back where it should be. it expects that unmetered air to happen in tandem with ccp duty cycle, so it's adding fuel.

also disabling it with out of range temperature seems to give me a good AFR, so i know it's compensating

like i said in the original post, i can tune around it in the maf tables to a point, but i'd rather do it 'the right way' and stop it from trying to actuate the ccp. i'm a bit concerned my tune will not be perfect until i do, since the ccp duty cycle doesn't seem entirely predictable.

ok, here's my first hurdle. 022A on the T side is the actual crankcase purge duty cycle. i'm guessing whatever routine causes the duty cycle to happen on the e-side must be updating that memory address.

i can't identify any other code on the t side that plays with it, so obviously the E-side has the code that sets the duty cycle

question is, how do i find out what the hell on the e-side is setting 022A on the t-side? i'm kind of lost with that one

i may able to contribute a bit.... i did get the SPI transfers between the two processors worked out.

it may not be much, but i haven't played with it that often.

if you had a moment to have a look sometime, and try to find some kind of E side reference to that 022A memory on the T side, i'd sure appreciate it

i'm still assuming whatever routine is cycling the CCP has to write to that address

hmm...... i'm not seeing that byte get transferred from one to the other....

on the T-side, that byte is written to in 3 locations:
6D6B is always clear
6DA0 is always 255
6E16 can be cleared, 255, byte 295 or byte 227.

byte 295 is only written to in one location (B9D3), where it is a copy of 199D(which is never written to, so it may be external hardware or just for reference). so that likely isn't it.
byte 227 can be a copy of byte 228(which can be 227 + certain calibration values), or at 7125, where it is the result of a couple of tables that i haven't marked.

maybe my assumptions were wrong, and it is all done in the t-side

thanks for your help, i'll keep working on it

if you use IDA Pro, i could send my disassemblies, i've only really added in enough to understand what i've wanted to learn about though.