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COS3 cold lean startup solution
Okay, after some serious trial and error, i have a solution to the lean cold start problem associated with the 2003 COS #3. It might be an issue with other years and COS's, but i dont know. I use COS #3, OS# 03190003.
So we know that table {A0008} does not work correctly for this OS, this is a fact. I can populate that table with MAX values and it makes no difference in the commanded AFR at start-up. It will start around 12.xx and be right up to 14.7x in the matter of about 20 seconds. This is confusing to explain, so i am just going to use a copy of an Email i sent to justin.....
Quote:
Well the math works out as if
{A0008} is being used, just not incrementing or decrementing properly. If i
start my truck and the ECTs are 68*F, the value in that cell in table
{A0008} when multiplied against the commanded AFR in {B3647} "IS" the AFR
thats being commanded. Know what i mean? The 68*F cell in table {A0008}
when multiplied by the commanded AFR in {B3647} equals the AFR being
reported by the scan tool. BUT, it will not increment with the rest of the
values in {A0008}, it will only begin to increment once the value in {B3650}
is less than 1.0000. I set my {B3650} to all 1's until 140*F. So follow me
here because this is kind of confusing I know, but this seems to be how its
working......
--I start the truck and the ECTs are 68*F
--The {A0008} table has the value 1.1155 in the 68* cell
--1.1155 multiplied by 0.9951 (which is whats in my {B3647 as commanded EQ)
= 1.1100 or 13.17AFR
--It will command 13.17 until the ECT value in {B3650} falls below 1.0000,
which in my table is 140*F
--So it will command 13.17 AFR until the ECTs reach 140*F then it will
increment up to 14.70
If all the values in {B3650} were 1.0000 it would never start to increment
and would always stay at 13.17. Now if when I started my truck, the ECTs
were say 104*, then what ever value in the 104* cell in {A0008} is whats
multiplied by the commanded AFR in {B3647} and it would stay at that
commanded AFR until the value in {B3650} fell below 1.0000. Follow me? LOL
Basically it all depends on what the ECTs are when you start your truck, if
they are higher, your commanded EQ will be higher until the value is
satisfied in {B3650}. My head hurts, but it works...:)
Basically in order for your commanded AFR to be rich at start-up you need to have a value of 1.0000 in {B3650} up to the point (ECT) you want the AFR to start incrementing. I have all 1's in my {B3650} up to 140*F, at which point my AFR will start to increment. It takes roughly 30 seconds to increment with the values i have in {B3650}, so by the time my AFR is 14.70, my ECTs are 150'sh (F).
I am going to post a copy of my tune to show what i mean, in this copy of my tune and log, i had 122*F as the starting cell for incrementing the AFR, but I have since changed it to 140*F. In that tune, i was messing with a few other tables in the "cranking/start section, but have since ruled them out and found that {B3650} is the key table here. Have a look.....
