I read the sticky on the 02 constants but have a question on which table or tables too modify . The Mask i have is $OD and what i have done so far is tuned my idle in open loop doing a plug reading and have a tanish gray colour on the tip of plug . The WB shows a 16.3 AFR at idle the other VE tables i have tuned in open loop to reflect a 15.0 AFR . At idle now in closed loop the only table i alterd is the idle table by minus 100 Mv and it did not make any change to the BLM's . My thinking is if i change the other three tables minus 100 Mv i will be running to lean off idle . Can some one point me in the right direction maybe on my idle table i have to go even less Mv ? Here is a copy of my tables that i currently have .

Your points in the tables are equal, there must be some spread between the values for the control to bounce across.
Here are some links to info describing how the system works with the tables, etc.

RBob's explaination of the 747 but it applies to most of the ECMs.
http://www.diy-efi.org/gmecm/papers/747fuel.txt

Here's a discussion about shifting the values (mostly at idle but still applies)
http://www.thirdgen.org/techboard/di...-contants.html (o2 contants)

Another one on shifting the table values for using other fuels that also describes the operation. There is a spreadsheet on my post that shows the $8D tables and how they would be setup. Yours "may" have the same structure but different addresses.
http://www.thirdgen.org/techboard/di...-richer-f.html (how to command a richer A/F in CL?)

This thread has a later post concerning how I stated to move the values that might be an issue.
http://www.thirdgen.org/techboard/di...rich-lean.html ($8D - O2 Rich/Lean Upper Zero Reference table)
I never saw that last response and will be checking into it.
Anyway, HTH.

Thanks for the reply i will read those and hope i understand alittle . Some people are cut out for this stuff and others like me sure take the long way around hard to sink in LOL .

Well i re-read an re-read an tried quite a few different things an the tables i have listed except the bottom one have nothing to do with idle , only off idle so i found out . I have a table specific for 02 idle and i have been trying to richen it up but some thing is fighting the change . In the data log i see the change then after about two minutes i see it going back down to 14.7 and i'am aiming for 16.0 or close . I have my mean set to 700 mv my rich set to 850 mv and my lean set to 550 mv i believe this is what i'am looking for but can't find what is fighting the change . Anybody have some imput on this as i'am stuck

What version xdf are you using?

I got the file from Moates $OD_v03.XDF . I'am not good with names some one from here made the XDF .

You say its going back to 14.7 after a few minutes, you do have 4E85 Bit 0 "Closed Loop Idle" enabled dont you?

Do you have desired AFR datalogging enabled and do you datalog?

Drumer919 if your asking me to look in the code for 4E85 Bit 0 , ain't gonna happen i have no clue to be honest with you . I do not no how to change that sorry . Yes it is going back to 14.7 after a few minutes . I will look into it though an maybe i can figure it out with more reading .

Sorry Drumer919, but that's not my xdf.

95 4x4 here's a link to my $0D tuning files:
http://www.fullsizechevy.com/forums/...ing-files.html

The xdf your looking for is titled "Advanced 0D v175.zip".

For adjusting the idle 02 values you need to use the constants at 4940, 4941, and 4942.

Humm i thought i had that one guess not . I see your posts an alot more reading LOL TY

I beleive these tables are the ones i'am changing now .

Drumer919 i have been looking for 4E85 in the code and i can not find it . Yes i have been doing data log's with DataMaster and i also have the LM 1 recording too .

Its called Closed loop idle, if your using TP use item finder (control F) and either search for "closed loop idle" or search for "4E85" and choose "at or containing this address"


Do you datalog "desired AFR"? You can do so in place of battery voltage, that way you can see if when it goes back to 14.7 if its doing whats commanded or if its still commanding where you want it but the tune is off.

To enable its at $520C, stock value is 00A1 and like I said makes battery volts show up in the log but if you change it to 026D then your datalog will still say battery volts but the value will be the commanded AFR.

Edit: I just re-read your first post, are you changing your AFR by altering the VE? Really the way to control AFR is by enabling 400D- Bit 0 "Open Loop AFR Enable", that will let the PCM use whatever value you set in table 4BB4 -"Open Loop AFR vs temp vs vac". Once you enable the bit it will use the open loop table for closed loop AFR control. You shouldnt try to command different AFR's by changing the VE, once you have it correct for you engine you should leave it be (you know its correct when desired [aka commended] AFR matches actual.)

drumer919 you gave me alot to look at

No closed loop idle is not enabled
Yes i dataLog desired afr in place of battery volts
Yes it is doing what is commanded
No i'am not altering my VE
No i do not have Open Loop AFR Enabled

I see some light now and from what you just pointed out i was altering the wrong idle 02 tables seen from your attachment . I will enable the Open Loop Afr switch an adjust the Open Loop vs temp vs vac i understand this now . I now see why i was having a hard time , trying to alter the wrong tables and not even having the correct bits enabled hummm part of learning . Now that i'am on the right track maybe i will make some head way instead of beating my head that hurts .Thanks Drumer919 i will try out these new settings , you to 93V8S10 for your Advanced 0D v175 quite a difference from what i had .

Drumer919 i have done everything that you suggested and i guess i just opened a can of worms . My idle AFR is all over the place and my desired AFR in battery volts does not work , my mistake i beleive it never did now that i look at it . Seems like i still have something else to look at just wants to go back to 14.7 . I attached a small data log if you wanted to look at it an maybe you can see what is happening , i think i have a bit on that should not be ? Looking over the Bin i can't seem see what would be causing this issue .

Any one else have any imput on this ?