Ronny

iTrader: (1)

i am runnning 92 octane 10% ethanol.

WB shows CL A/F at about 14.7/1 sometimes higher about 14.9/1.

what need i change in .bin to allow say a 14.5 A/F in CL?

dimented24x7

iTrader: (2)

IIRC, 14.7:1 is hard-coded into the ECM as the closed loop air fuel ratio. If you change the desired closed loop AFR, the ecm wont enter closed loop.

Ronny

iTrader: (1)

hhmmmm. if the nb02 swings over .450 mvolts as that is what it is designed to do. can't it be asked to swing over a larger value and report that as 14.7? maybe i am off base.

i see in wisconsin we have 10% ethaol for years. now i see 20% ethanol at a small cost savings. as well as E85 more common. seems like it would run leaner(20% ethanol that is) as a result unless the stoich is modified.

Dominic Sorresso

Ron,

I made that change to Stoich because we have 10% ethanol in IL as well. Go to the EBL constants. There's a Closed Loop-Stoich AFR setting. I have mine at 14.3. BTW, I learned from RBob (what else is new?) that constant is only good for C/L and not PE. I was shooting for 13:1 AFR at WOT but Bob reminded me about ethanol, so now I am looking for about 12.6 for WOT.

RBob

iTrader: (1)

Dominic is using the same 10% ethanol fuel. He changed the stoich AFR term to 14.3 along with lowering the PE AFR values. This is to bring the PW calculation into better alignment.

When in closed loop the O2 window values define the actual AFR. There are 3 values used when in idle. Then 3 tables of values used when not in idle (vs MAP). Adjust those to make the resulting AFR richer or leaner.

RBob.

{edit: Dominic types faster then me. . . }

Ronny

iTrader: (1)

thanks.

so..

1. i change the stoich term(constant) to 14.3

2. in TP they are referred to as "idle window values" or close. i raise them a bit.

3. same with off idle vs MAP "window values". i raise them a bit.

4. i verify results on WB log.

Dominic Sorresso

Ron,

Here's what my settings are for that. Notice how much lower the Idle terms are. That seemed to help my idle because of the overlap in the cam.

Ronny

iTrader: (1)

thanks... will compare to mine. i think you already provided that to me and i may have already copied into my .bin.

note: see RBobs comment on the MAX ASYNCH and MIN ASYNCH PW. he suggests leaving those alone. i verified a couple nights ago yours are much different than stock EBL per the .bin you sent to me.

dimented24x7

iTrader: (2)

The only thing you really have to change is the stoich AFR. The rest of teh closed loop PID stuff shouldnt need any changes unless your radically changing the fuel mixture. The O2 is going to target stoich no matter what. Changing the stoich AFR will help keep the BLMs from getting out of hand

Fast355

iTrader: (2)

I have been using the same 10% fuel for quite some time now. Mine likes stoich at 14.1:1 with PE around 12.5-12.6:1.

JP86SS

iTrader: (1)

[quote=RBob;3103931]When in closed loop the O2 window values define the actual AFR. There are 3 values used when in idle. Then 3 tables of values used when not in idle (vs MAP). Adjust those to make the resulting AFR richer or leaner.

RBob.
quote]
On $8D I've been trying a strategy of adjusting all 3 of the off idle tables up by 100 mV then putting a 100 mV setting in the coolant modifier table.
This allows me to shift the o2 windows as a set by changing the values in the coolant table. (Rather than changing 3 tables each time)
The coolant table subtracts from all 3 so by adding 100 to the main tables, the 100 in the coolant table brings them all back to stock settings as the starting point. Adjust ALL of the values in the coolant table to be the same.
The window relationships remain the same, your just moving the set around.
Something to try.

JP86SS

iTrader: (1)

I made up a sheet to show the amount of shift that happens and calculates the new table values for you.
Wouldn't upload so here's a link to it.
http://www.wideopenwest.com\~Johnand..._TABLES_8D.xls
can run it from there if you have excell or save as...

Edit the table info at the bottom.
Edit the modifiers at the top with your window value from the bin.

JP

RednGold86Z

iTrader: (1)

In order to "read" the wideband correctly, you still need to look for "14.7:1" displayed. Widebands also work on O2 and CO, not ACTUAL AFR. They are displaying 14.7 based on standard gasoline stoichiometry, and will display 14.7 at full ethanol stoichiometry until you reprogram the display to SAY 9:1 is what stoichiometry is (or for whatever proportion of Ethanol to Gasoline, and the resulting stoichiometry AFR)

End result of switching fuel is:
- You still calibrate to target BLMs of 128.
- You still can use same switchpoint of NARROWBAND O2
- Still add 13-19% more fuel for PE (which you'll still want the WB to SHOW 12.8 (or whatever you desired before), unless you've changed the WB display properly for the fuel, then richer).
- In order for the VE to display closer to correct numbers (fresh cal or when switching from a known good gasoline calibration to a E10, E20, etc..) you'll have to change the stoichiometric AF, and change the math for XDF DISPLAYED PE, because PE is a MULTIPLIER, and you still want the same MULTIPLIER as before, but since the fuel is different, the AFR is different.

Ronny

iTrader: (1)

i made changes as RBob suggested. to early to tell the effect. the WB this morning seems to still be at around 14.7/1. i will double check my changes.

i do understand i need to do "custom setting " on WB. i may do so and learn to use lambda 1.00 (adjusted for 10% ethanol). still using NB to adjust BLM. another project for next season.

69 Ghost

iTrader: (1)

John can you elaborate more on what you are doing. I guess I am getting lost here. I have 2 thoughts. I lowered my mv constants to lean out my idle. I am also thinking that I want more fuel to be commanded at higher RPMs. I guess what I am asking here is can I use this strategy to lean out my idle areas and richen up my higher MAP/RPM areas with this setup?

Ronny

iTrader: (1)

Dom: i made those changes exactly as you suggested. will need more time to confirm i am running richer than prior on WB.

changing air temps are skewing my BLM's for sure. 32 deg F this AM. no heat to TB. the RPM heads has no crossover either? i read the first attempt as using TBI caused the TB to ice up big time prior to Thermac. i will test that!

junkcltr

iTrader: (1)

Well said.

For all the $8D users reading this. Here is how you adjust for 10% Ethanol:

1) Change the Stoich AFR Constant from 14.7 to 14.3 (or 14.13)..you decide what E10 stoich is.
2) DO NOT change your PE tables
3) Add a new XDF item to report "AFR ETHANOL". For the DIY-WBO2 XDF reporting location I multiply the "GAS AFR" by (14.3/14.7). There is a very small error that is not noticed when doing this.
4) DO NOT play with the O2 cross-points/thresholds.

Now compare the ECM reported "TARGET AFR" to the ETHANOL AFR"


If you find that you are changing the PE tables and or O2 tables then your tune is off..and it is not due to E10.

EDIT: If using an AFR gauge, it will report the AFR wrong. Note the (14.3/14.7) that was done to the XDF above. That needs to be done to the AFR gauge.

RBob

iTrader: (1)

Not all GM ECM masks use a multiplier for PE fuel.

Recall that the original poster asked about how to make the AFR richer in closed loop. Moving the O2 window set points is how that is accomplished. Which is what was posted.

RBob.

JP86SS

iTrader: (1)

Right, I was indicating how to shift the CL AFR not necessarily for 10% E.
The idea in a nutshell was to add 100 mVolts to all the current values and let the coolant table (all set at 100) take it back out. (back to stock settings)
Gives adjustment to all 3 tables by only adjusting the coolant table.
Since the coolant table only subtracts (leaning), this allows for positive adders (richer) by way of NOT subtracting all of the added amounts in the tables.
Can also tweak the coolant table for different temps if you go to CL early in the warming cycle.
Grab that spreadsheet, the graph helps to understand.

dimented24x7

iTrader: (2)

Theres no real easy way to fix the AFR drift with SD and TBI, so your not going to be able to get the AFR's perfect due to the fuel dynamics. IMO, once its within +/- 5% BLM wise, your job is done. Also make sure that you datalog at a consistant engine and intake temp so you get relatively repeatable results.

junkcltr

iTrader: (1)

For the CL and drift, Did you guys try changing the PI gains and timers?

dimented24x7

iTrader: (2)

My reference was to the variance you get with air temp, which is due to the fact that you really cant know what the true intake temp is with a wet flow system. Once gas enters a low pressure environment, it acts like refrigerant and causes the intake charge to rapidly cool as it evaporates. This will cause the BLMs to vary depending on what the outside conditions are.

RednGold86Z

iTrader: (1)

Which is kind of a good reason to target lowest observed Idle BLMs between 118-124, and limit the min stored BLM at shut down to be 128 (for cell 0, or whatever idle cell is). Then, when you start up, you'll have a few percent more fuel, in case you shut down at the low BLM point of drifting.

TBI manifold temperature varies a lot. Even the same IAT (if external) and ECT readings can require different fueling, depending on if the car was driven or just idled. If I were doing a TBI, and wanted high accuracy, I'd probably mount the IAT in the manifold, purposely hoping it heat soaks - just as the manifold does. But, probably won't do a TBI for myself in the next several years

Fast355

iTrader: (2)

I only limit my BLMs to 108/148 for both running and startup. Runs much smoother on the highly variable fuel we have here.'

My IAT is mounted in the manifold. I am using the IAT open style, it works very well.

junkcltr

iTrader: (1)

Does the TBI code have something to adjust the fuel MAT like the $8D does?
Something like: BPW_MAT = (COOL_TEMP - MAT) * LKUP_CONSTANT + MAT

The lookup constant is vs. airflow. You could adjust the table if it is there. It would remove some of the variability. It would correct the BPW better for intake temp. changes.

dimented24x7

iTrader: (2)

The later PCMs and EBL have the blended temp. terms. What would be neat is to mount a very small thermister in the manifold under the TBI instead of the standard one, which has a good deal of thermal intertia. You could probably get things pretty close.

Ronny

iTrader: (1)

DIM: i just added an IAT sensor ay the air cleaner(8746-EBL). unfortunately it is not sending a signal to ECU at this time. was hopeing to get a feel for what it adds to drivability cold start(40dF) vs a heat sinked manifold and underhood hot temp. question: is a thermister a 0-5V devise as i believe the IAT is? if so where can one be found? there is no room in my AC(2 x 14) for IAC so it is attached under the AC! i would have like to have placed within AC.

junkcltr

iTrader: (1)

Since this is an E10 topic. Does anyone know if there are gas stations that add the 10% ethanol to gas that has the octane rating on the pump? For example, "93 octane" written on the pump would be 93 octane base gas with 10% (110-120 octane) ethanol added to it making it about 95 - 96 octane fuel.

All that I have read for all gas stations is that E10 rated at 93 octane is a real 89 octane base gas with 10% Ethanol added to it to make 93 octane. Sure, the "Ethanol is great" websites brag how it is 110-120 octane........but that is useless because the oil companies user lesser octane gas with it.

91chevz71

IAT open style? the birdcage one? I need to move my IAT to the manifold, but am confused on which sensor to use (CTS or birdcage IAT)

junkcltr

iTrader: (1)

open style is the 198x - 199x V6 open style. Like the mid 1990's LT1 open IAT. Yes, it looks like a little blue bird inside a cage. This sensor responds much faster than the brass MAT. It is also more prone to failure.