Open Loop Eq Ratio Table Usage

[INTHERED]

I was doing some datalogging with my WB and I noticed that the commanded air/fuel ratio was either 14.68 or the values in my WOT PE table but nothing in between. Under what conditions does the PCM use the Open Loop F/A vs Coolant Temp vs MAP table (Open Loop EQ Ratio table) to make fueling corrections ?

Thanks >>>> INTHERED

[Bill@HPTuners]

when its the richer of the tables.

[WS6FirebirdTA00]

or if you are in open loop, hence the name.

[Dirty Howie]

I drove around for more than two weeks (tuning VE and MAF) with OLFA set to 1.0 (stoich).

I reset the table to stock after tuning but not sure why..it was starting/idleing fine!!!

Seems that if the Maf fails and OLFA is set to 1.0 all is well in non PE. And then PE table is there when you enter PE.

So I guess I really don't understand OLFA necessity......


DH

[INTHERED]

or if you are in open loop, hence the name.

We talk about open loop and pe differently but aren't they really the same ?
When I was datalogging my commanded A/F ratio I either saw 14.68 which is stoic or 11.50 which was based on my PE table value of 1.276.

Has anyone ever tried setting the PE table to 1.0 and using the OL EQ table to control the A/F since it seems to me that might add more controlability to the fueling under different MAPs and RPMs ?

INTHERED

[WS6FirebirdTA00]

OLFA commands fueling when in open loop based on ECT. It is an eq ratio to command the AFR. That is the table used to command any non PE fueling, all the time. Once you enter PE it will use the richer of the two tables.

Most stock cals have 1.00 in operating temperature ranges, so if the MAF failed it would not dump in fuel during normal driving, you will not notice it.

[jimmyblue]

I've been thinking for some time that the PE vs
RPM ought to be for "special cases" and the
EQ vs MAP (vs ECT) should control open loop
fueling. This is because best fueling changes
strongly with MAP (IMO) and not much w/ RPM
(except when fighting fuel fade or MAF pegging
etc.).

In this case you'd let PE mode enable as you like
but keep PE value down, except where you need
an "upside" that's really RPM-involved. I prefer a
response that's smooth across the pedal range,
not an all-or-nothing PE type scheme.

Of course some of the custom OSes have the
"boost enrichment" but I'm talking vanilla, NA.

Curious what others think about this.

[WS6FirebirdTA00]

You dont want to rely on the OLFA for PE fueling, IMO.

[INTHERED]

OLFA commands fueling when in open loop based on ECT. It is an eq ratio to command the AFR. That is the table used to command any non PE fueling, all the time. Once you enter PE it will use the richer of the two tables. Most stock cals have 1.00 in operating temperature ranges, so if the MAF failed it would not dump in fuel during normal driving, you will not notice it.

So if I understand you correctly the only time the OLFA table commands the A/F ratio is during an MAF failure or when the ECT and IAT have not enabled close loop operation based on the Closed Loop Enable Coolant Temperature vs IAT table ? So essentially there is no open loop A/F commanded by the OLFA once the vehicle has warmed up ? Its either stoic or PE then.

INTHERED

[MNR-0]

I've been thinking for some time that the PE vs
RPM ought to be for "special cases" and the
EQ vs MAP (vs ECT) should control open loop
fueling. This is because best fueling changes
strongly with MAP (IMO) and not much w/ RPM
(except when fighting fuel fade or MAF pegging
etc.).

In this case you'd let PE mode enable as you like
but keep PE value down, except where you need
an "upside" that's really RPM-involved. I prefer a
response that's smooth across the pedal range,
not an all-or-nothing PE type scheme.

Of course some of the custom OSes have the
"boost enrichment" but I'm talking vanilla, NA.

Curious what others think about this.

Shhhhhhh. Don't let the cat out of the bag...

It lends easily to more mid-range power as enrichment progressively comes on meaning you can afford to be more liberal with your spark advance. Power delivery is smooth - economy ehanced - if done right. Note that this is essentially the equivalent to EFI Lives OL overide when dialling in the VE MAP.

Don't even attempt this without dialling in your VE MAP and be prepared to lose your O2s, as this won't work in closed loop. You will need a WB but he who doesnt tune with a WBO2 shouldn't be tuning.

[S2H]

I dont think its intended purpose was as MNR and Jimmy are suggesting...but it does work for an NA vehicle..sort of..LOL
if you get into Forced Induction then its worthless...

you can always use adder tables in the SD enhancements like the VE TPS table
and of course I like to make a blend of all of the Fueling related tables to get what I need...

[Billf6531]

I'm going to try leaner values (.965) in the SD VE/TPS table (10-30 TPS) and in the OLFA table (35-50 MAP) for fuel economy if Spring ever gets here. Unless someone has an off-road version of OS 1271016 that has lean cruise enabled for Canada.

MNR-0, do you have any examples of additional mid-range enrichment and timing values that you can share? LS-1 specific would be great.

[alanderson1978]

You will need a WB but he who doesnt tune with a WBO2 shouldn't be tuning.

This is about the only part of this thread I understand well enough to agree with.....

The only exception is diesels and there you can replace 'WBO2' with 'EGT'

[MNR-0]

I'm going to try leaner values (.965) in the SD VE/TPS table (10-30 TPS) and in the OLFA table (35-50 MAP) for fuel economy if Spring ever gets here. Unless someone has an off-road version of OS 1271016 that has lean cruise enabled for Canada.

MNR-0, do you have any examples of additional mid-range enrichment and timing values that you can share? LS-1 specific would be great.

Well each to their own as far as whether this works for you or not.

Mid-range meaning around 0.48-0.52g/cyl. I tend to run 2-3* more timing there with my 236-240 cam than before purely because when I reach those cells, the load is already around 75-85kPa and so enrichment has begun to apply. I ramp it in just after idle kPa. So for example, my idle is 70kPa, I begin enrichment from 75kPa till WOT throttle AFR at 100kPa. Its slewed in so it doesnt flood the engine at part throttle.

I have issue with TPS-VE multiplication as it is not load sensitive. I can be doing 1600RPM at 3% throttle cruising as well as 20% throttle accelerating from a stand still. I want different AFRs at those load ratings but same RPM. I also want my AFRs to fatten slightly during gear changes to alleviate any chance of detonation under sudden load.

Lean is mean for power, but rich is bitch for torque.

Personally, I think this table is a waste of time. But if it works for you, then all well and good.

[MNR-0]

I dont think its intended purpose was as MNR and Jimmy are suggesting...but it does work for an NA vehicle..sort of..LOL
if you get into Forced Induction then its worthless...

you can always use adder tables in the SD enhancements like the VE TPS table
and of course I like to make a blend of all of the Fueling related tables to get what I need...

I disagree with you there. This is how EFI Live tuners do their turbo part throttle stuff. You do NOT want closed loop 14.7 with instantaneous 12psi boost on tap, and since boost exhibits load sensitivity as well as RPM, its safer and better for torque to bring enrichment in progressively as boost increases.

Now I don't know if this table scales along with 2-bar MAP sensors, but if it does, then this is how I would tune for boosted applications.

It is true that tuning is personal preference as well as professional experience, and there is more than one way to skin a cat. This is my current preference. I appreciate others have differing opinions.

My only recommendation is to be open minded to alternatives. You never know till you give it a go.

[WS6FirebirdTA00]

I use mine for extra enrichment above 75 kPa so I can run the timing I want. It is not much richer, but here are times that PE is not kicking in and I dont want to run the TPS so low where it drinks fuel. Also, it helps on tip iin throwing in the extra fuel and I feel I get better response on the streeet with it.

[jimmyblue]

My main beef is, RPM is not a good "load signal"
but MAP is (other than at the extremes of low &
high RPM) an excellent indicator. RPM-based PE
is all-or-nothing and can't be fitted to load
(other than 100%) well.