COS3 cold lean startup solution

[Whippled 496]

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.....

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.....

[Tordne]

I'm glad you posted this as it gives a really good indication of what is happening!! You are absolutely right about about the B3650 and the commanded AFR NOT changing till it equals something other than 1.00.

Interestingly the values in my tune are not 1.00 at any point. this may mean that other OS's have the same issue but the values in these tables on other tunes (which people probably don't change often) means the problem never actually is witnessed.

Have you sent this to Ross/GMPX? If not I'll PM him with a link.

[Whippled 496]

No I have not, but i would love for this to be fixed so we can correctly utilize {A0008}. It would be much easier than doing it this way... Yes, please send them a link, thanks Tordne.

[dc_justin]

Subscribe.

[Tordne]

Email sent. I may actually try with your values from the B3650 table. Would be interested if you could try perhaps using mine...

Paste the following numbers into each column in your table and try for me if you could:

0.970215
0.970215
0.970215
0.970215
0.970215
0.970215
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.930176
0.930176
0.930176
0.930176
0.930176
0.930176

Cheers,

[GMPX]

I think the issue might be something to do with the Normal fuel and Ethanol fuel table blending and when A0008 is being factored into that equation. I'll look in to it.

Cheers,
Ross

[Whippled 496]

Email sent. I may actually try with your values from the B3650 table. Would be interested if you could try perhaps using mine...

Paste the following numbers into each column in your table and try for me if you could:

0.970215
0.970215
0.970215
0.970215
0.970215
0.970215
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.930176
0.930176
0.930176
0.930176
0.930176
0.930176

Cheers,

Okay, i will give yours a try. My numbers are very crude and really have no real meaning other than the fact that after 140*F the number is less than 1.0000. That is the only way i could make the AFR start to increment to my final commanded AFR.

[Whippled 496]

I think the issue might be something to do with the Normal fuel and Ethanol fuel table blending and when A0008 is being factored into that equation. I'll look in to it.

Cheers,
Ross

Thanks Ross, Im not going to question you, I know you had a small part in the design of the OS.... I look forward to getting this fixed up for sure either way. I can tell you that {B3650} definately has something to do with it though.

[dc_justin]

Email sent. I may actually try with your values from the B3650 table. Would be interested if you could try perhaps using mine...

Paste the following numbers into each column in your table and try for me if you could:

0.970215
0.970215
0.970215
0.970215
0.970215
0.970215
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.963867
0.930176
0.930176
0.930176
0.930176
0.930176
0.930176

Cheers,

That change alone won't cut it, as my B3650 has very similar values from the factory.

The big difference between my currently non-working warmup and 496s working is that he has added data to B3663 while I have not.

I'm going out now to try changes made to only b3663 and see what happens.

[dc_justin]

That change alone won't cut it, as my B3650 has very similar values from the factory.

The big difference between my currently non-working warmup and 496s working is that he has added data to B3663 while I have not.

I'm going out now to try changes made to only b3663 and see what happens.

Okay, B3663, nothing.

Changed my B3650 values to 1.0 up to 70*C and it stays rich up to that point...