ECM 12209 MAF Steady State Startup

[10_SS]

Anybody know what this table does? I used to have a hard time around 30-45F with a bad startup RPM dip that would almost stall after installing Whipple and updating to the 2bar OS, I found ways to fix it by adding open loop warmup fuel in this coolant temp area, but then I see this table... it has a strange dip right at 40F, the same temps I had this startup RPM problem.. this is the stock table... 2010 LS3 Camaro

Does this simulate airflow during first second or two to get injectors firing?

Stock 12209 MAF Steady State Startup.PNG

[kelleyperformance]

this forum proves to be not so helpful sometimes lol. SO many important questions like yours asked and rarely does even one person, tons of whom know the answer, will simply take the time to help a fellow tuner who may be learning the ropes or just an experienced tuner with a legitimate question... sorry you've had no replies man.

I get flack for things like that but its true- I found your thread searching for more info to help me better understand the exact same table. mine on my stock E38 LS3 (15' SS Sedan) is all zero'd out... which is odd since almost no other LS 4th gen ive found in my customer tunes or on the repository is this way.

I am prob wrong, but heres my thoughts on the table- its a "steady state" table for startup, with a step down table and a delay table to transition to the 'normal' steady state data. SO my assumption is, this is what the vehicle should be seeing airflow-wise upon startup initially. I think it just helps out the cranking and idle before fuel trims kick in. just my educated guess (semi educated :lol: ) hehe. did you ever get any more info on it? im trying to work through a little hick up on my personal car with idle upon immediately after start-up, and like stated my table is all 0's.. im going to input data from another LS3 and see what happens.

John

[10_SS]

I never figured out what it does, as some are 0'd out must not do much. I smoothed out my RPM flare with other tables, also I had a RPM dip after startup after switchign to the 2bar OS back in the day and ended up having to add fuel in the open loop table in that coolant temp 30-45F area to fix it.. it was lean stumble. these changes still apply to this day for whatever reason.

I always figure 95% dont know the answer, mayne a few do but something like this may just never be adjusted

[GHuggins]

In the tunes where it's used - I have increased it to just above or to correspond with my min air table for the rpm where it idles at... I did this to help with start ups and dips after start... If memory serves it also helps to get that startup "kick" where the rpms jump way up on startup... Other tables have to correspond like startup airflow and min air, but it seems to help... I also taper it in more instead of having the big dips like it does from the factory... That's just me - may all be in my head as to it actually helping? It also only seems to help with really big TB's and pullied blowers flowing some serious air at idle...

[kelleyperformance]

actually is does do something- but it is not a "necessary" table (for example, your MAF airflow table; if zero'd out, you get the idea). basically, what I learned is this table helps the ecm get a better idea of the amount of airflow that enters the engine immediately upon start up, until the ecm gets 'stabilized' S/S readings from main tables. ive been experimenting with the table and it does effect start-up and the few seconds immediately after start up (depending on the other two settings, delay, etc). still don't understand why my factory LS3 tune seems to be the only one with the table zero'd out... but then again all the Holden tunes I have ever looked at stock are fairly different from the US model cars- and obviously I mean USM Holdens.

[GHuggins]

actually is does do something- but it is not a "necessary" table (for example, your MAF airflow table; if zero'd out, you get the idea). basically, what I learned is this table helps the ecm get a better idea of the amount of airflow that enters the engine immediately upon start up, until the ecm gets 'stabilized' S/S readings from main tables. ive been experimenting with the table and it does effect start-up and the few seconds immediately after start up (depending on the other two settings, delay, etc). still don't understand why my factory LS3 tune seems to be the only one with the table zero'd out... but then again all the Holden tunes I have ever looked at stock are fairly different from the US model cars- and obviously I mean USM Holdens.

Yes, in my studies it's used for the first 2 to 5 seconds after starting or until airflow can stabilize enough for the MAF to read correctly...

[10_SS]

If memory serves it also helps to get that startup "kick" where the rpms jump way up on startup... Other tables have to correspond like startup airflow and min air, but it seems to help... I also taper it in more instead of having the big dips like it does from the factory... That's just me - may all be in my head as to it actually helping? It also only seems to help with really big TB's and pullied blowers flowing some serious air at idle...

OK now you have my attention... I never liked how high the Camaro's revved stock, was fine with stock exhaust but after louder exhaust it was kinda annoying.. I think I was hitting 1800-1900rpm, maybe it got worse with the Whipple, I dont remember. I have it down like a corvette now, ~1400-1500rpm or so. If I would have though to use this table maybe I could have saved some time. Maybe I'll see if the corvettes have similar settings...

K, compared to a 2013 Corvette manual... sure enough, it is 0'd out. You guys are right on the money I do believe.

[hjtrbo]

I've done a bit of research on this lately. Came across this thread after searching, and I did not come across much subject matter.

I have an oscillation at idle that I'm working through. I don't have any questions on how to fix as I'm learning more by doing. But the symptom of oscillation did allow me to see what this MAF SS can do. I'll show the data below, and maybe someone smarter than me can come along and work it out.

Firstly, the S/S Stepdown box is silly because I have tested values of 0.1, 0.01 and 0.001 which all make a very noticeable difference yet the lowest the box will show is 0.1. The current value in the screenshot is actually 0.01, but if you were to upload the tune you would think it has been zero'd out.
1.PNG

My oscillating idle is proving to be an advantage in only this case of testing the MAF S/S because I can see when the TPS is steady state.

After the MAF S/S air is less than the Desired Air OR the MAF SS Delay time is active then then Desired Air (ETC Position Setpoint) = MAF S/S Air + Proportional + Integral + Adders
Adders are the A/C air, fan air etc. if they are operating

Note, all test are with the car at normal operating temperature.

Test 1: MAF S/S Air = 9g/s, Delay = 4s, Stepdown = 0.01. Time from steady state TPS to start of oscillations = 4s
1.PNG

Test 2: MAF S/S Air = 19g/s, Delay = 6s, Stepdown = 2. Time from steady state TPS to start of oscillations = 6s
1.PNG

Test 3: MAF S/S Air = 21g/s, Delay = 4s, Stepdown = 0.001. Time from steady state TPS to start of oscillations = Ages
1.PNG

Test 4: MAF S/S Air = 19g/s, Delay = 1s, Stepdown = 0.01. Time from steady state TPS to start of oscillations = 6s
1.PNG

So it can be used for something. My take on it is you can use it to manipulate the integral term if you are getting heaps of wind up when in the first 10 seconds of idle. There is fair bit at play here obviously as the idle engine speed vs target is the error used for the P & I calcs. Off to the shed to try and fix my idle now.

Note, the log files are zipped up but because the forum doesn't like a zip file I chucked the .hpl extension on the end. To open, delete .hpl off the file name when you download it.

[GPGTP]

[QUOTE=hjtrbo;624242]I've done a bit of research on this lately. Came across this thread after searching, and I did not come across much subject matter.

I have an oscillation at idle that I'm working through. I don't have any questions on how to fix as I'm learning more by doing. But the symptom of oscillation did allow me to see what this MAF SS can do. I'll show the data below, and maybe someone smarter than me can come along and work it out.


old thread but i thought i might respond to help future searchers. Usually an oscillation after start up is from 1 of 2 things. Either too rich of an AFR or from too much airflow. AFR being too rich is self-explanatory but airflow is because the idle spark closed loop logic will max out negative timing correction essentially leaving zero spark control at idle. Hope this helps someone.