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. :notacrook:

[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...

[Tordne]

Did you try the values I posted?

[dc_justin]

Did you try the values I posted?

Mine were very similar from the factory (with the addition of multiple columns for E80 fuel). Any value other than 1.0 and it has not effect unfortunately. :(

Stock, mine were:

0.977783
0.977783
0.977783
0.977783
0.977783
0.972900
0.944092
0.929932
0.919922
0.909912
0.899902
0.889404
0.879883
0.864990
0.864990
0.864990
0.864990
0.864990
0.864990

Now, I have:

1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
1.000000
0.879883
0.864990
0.864990
0.864990
0.864990
0.864990
0.864990

[Tordne]

Gotcha. So I guess we need to let Ross have a look at it as it is obviously not exclusively related to the B3650 table.

[Whippled 496]

Ditto what Justin said. Those values did not work for me Tordne. Seems it has to be populated with 1's up to the point you want to start enrichment decay.

Sorry to be a pest and not to get side tracked from the original issue, but I have another problem. I noticed that adjusting {B3650} and/or an error in the way {A0008} works in conjunction with {B3647/49}, i get wierd commanded AFRs. The file i posted in this thread shows my commanded AFR in {B3647/49} being 14.7018, but the commanded AFR that shows up in the scan tool is 14.79. When i made further adjustments to {A0008} and {B3650} to try and dial in my enrichment decay, I ended up with a commanded AFR of 14.32. And the odd thing is, I made no adjustments to {B3647/49}. This is very aggrivating because i didnt notice it until about the 3rd itteration of AutoVE tuning my VE table. I just happened to look at my commanded AFR in the scan tool and it was 14.32..:nixweiss:

I may back out of the COS3 and go back to the 1bar until some of these issues are fixed, it has me worried about what other small variables might be out of whack that might cause problems.

[DrX]

Subscribing:)

[Whippled 496]

Subscribing:)


Me too....LOL

[GMPX]

FYI, I've Emailed Whippled 496 a new tun file to try.

Cheers,
Ross

[Whippled 496]

Thanks Ross, I responded to your Email. I will give this a shot tonight and let you know the results. Thanks for the quick response.

Jimmie

[TAQuickness]

Very interesting find Whippled. I've been following this thread pretty close. I'm running COS5 for the Fbod's and do not have this problem. But, I did find B3650 to have interesing effects on cold start behavior.

[DrX]

Looks like I'm not receiving my notifications today. Guess I'll have to keep checking in. Hope the new .tun works out.

[Whippled 496]

It did work out well, and worked like it was supposed to. I sent Ross the log to look over. If he says its okay, I can post it up, but i think he will want to make the final decision. I imagine he will upload it to the download section.

[RonC]

I have the same startup problem with my 2005 truck with COS 5120003. I also have a 2000 truck with COS 1270003 that doesn't have this problem. It sure would be good to have it fixed. Thanks for all your hard work.

RonC

[Chevy366]

Ditto , 05 COS3 , let us know how to fix !

[DrX]

Ditto; 04 COS3- 04073003

[Tordne]

Thanks very much to Whippled 496 for the first post with a very good description of the problem and some other findings!!

The log and tune were really good for looking at the symptom! The resolution has been identified, and successfully tested. An update will be provided soon, there are a lot of files to go through.

[Whippled 496]

No problem, just doing what i can to help out. DC_Justin brought it to my attention first, i just followed up on trying to find the resolution. For those of you who are having problems like i was, you can use my fix for the time being, its not perfect, but it will keep you rich through warm-up. Just use the values i have in my B3650 table. I posted the tune in the first post of this thread.

[GMPX]

Thanks Whippled 496 for your confirmation.
I'll be busy applying the code fix over the next couple of days to all 2003+ O.S's (with the normal and E85 tables), actually, it might not even take that long, it's a simple change.
When done I'll create a new thread under custom O.S's with a link to download the tun files.
You won't need to do anything more than a full flash, then a cal flash of your existing tune.
Whippled 496 also highlighted an issue where he's commanded AFR was a little out compared to the scantool AFR, I'm not sure if this may simply be a rounding issue more than anything between the table and the scan PID. I think it was like 0.06 or 0.07 AFR, so by any means not a real issue.

Cheers,
Ross

[ringram]

Nice, Im hoping this is the fix to the issue I have always had with COS5 & COS3 where GM.AFR bore no resemblance to my commanded B3647 AFR, sometimes like 2.0 AFR out! I posted logs up a while ago and tune files, but it wasnt chased down.
I also got a log from last night with the same problems.

Ross, Id love a test COS3 or COS5 to try. 129000x please :)

[GMPX]

Richard, that O.S should not be suffering this issue.
FYI, that is the same O.S I am using and I've never seen AFR errors like that, please Email to log file to me (and tun too), sorry I missed it all the first time.

The new 2003 + tun files with the fix are available here -
http://forum.efilive.com/showthread.php?t=4285

Cheers,
Ross

[ringram]

Yeah realised Im running a 129000x which isnt an 03+.

Ill get you the log and tune asap. Thanks Sir.

[Tordne]

Nice one Ross, that was quick!!

[Whippled 496]

Fantastic! Thanks for the quick work Ross. Did you find anything else in the OS that was not correct that would entail me to alter my tune at all?

[DrX]

Nice to have this working.:)