HOWTO: Disabling closed loop O2

[Roland@pcmtec]

To disable LTFT when you have no O2 sensor or require it disabled due to large camshafts etc set the following 3 parameters.

 Set auF0165 LTFT Learning Max to 1.0 

Set auF0166 LTFT Learning Min to 0.0

Set auF0170 LTFT Learning TPS Max to 0 counts

 

Old method (does not work for all vehicles).

auF0164 LTFT Enable should be all that is required to disable closed loop permanently.

Set auF0163 to 4096 degrees. This will mean the O2 sensor is never "up to temp" and hence the O2 logic remains disabled.

Or set the delay time to 1000000000 (this is actually clock ticks and not seconds)

Or set auF0162 to 1000000000 for all temperatures.

UPDATE:

on FGs the best way is to just set the A/D Count to 0.0 on the Open Loop TPS Transition table auF0153 as the above tables have been reported to not work on FGs

 

[fordsrule]

Does it require to change all the cells in the  A/D Count column, or just the 320?

Thx

[Roland@pcmtec]

2 hours ago, fordsrule said:

Does it require to change all the cells in the  A/D Count column, or just the 320?

Thx

Depends what you want to achieve.  Pick the rpm you want to disable it at, and then pick the TPS threshold you want to disable it at...

[fordsrule]

2 hours ago, Roland@pcmtec said:

Depends what you want to achieve.  Pick the rpm you want to disable it at, and then pick the TPS threshold you want to disable it at...

Ok

I've read that this proceedure is recommended for tuning wideband, do you agree with that?

Cheers

[Roland@pcmtec]

On 5/17/2019 at 4:34 PM, fordsrule said:

Ok

I've read that this proceedure is recommended for tuning wideband, do you agree with that?

Cheers

The whole point of disabling closed loop fueling is to check if your commanded lambda matches the lambda measured in your exhaust. If you leave it enabled it will be blending at lower rpm so it will be transient and your data won't be useful.

So if you are testing open loop only, you could just set all cells to -100, if you just wanted to make open loop occur earlier (eg a permanent change) then you'd only disable it at the rpm and TPS points you desire and most likely leave a blend still there so the transient is smooth.

[fordsrule]

13 minutes ago, Roland@pcmtec said:

The whole point of disabling closed loop fueling is to check if your commanded lambda matches the lambda measured in your exhaust. If you leave it enabled it will be blending at lower rpm so it will be transient and your data won't be useful.

So if you are testing open loop only, you could just set all cells to -100, if you just wanted to make open loop occur earlier (eg a permanent change) then you'd only disable it at the rpm and TPS points you desire and most likely leave a blend still there so the transient is smooth.

Ahh, i think i undetstand, thankyou for your help once again

[Roland@pcmtec]

Not sure the best place to put this. But for now here are some flags you can datalog to diagnose why a car is in open loop

Driver demand:

MID126793 == 1 WOT Open Loop Demanded

 

If any of the following are true ol_exc_flg will be set to 1 which also forces open loop

 

er_ful_req == 1

Engine Running On-Demand testing requires OL

 

MID31448 == 1

Intrusive EGO monitor open loop. This only occurs if abnormal switching is seen on the O2 circuit. Eg lean for an extended period of time. I believe this only occurs for V8s if one bank doesnt match the other bank

 

MID63647> auF2504

Extended decel open loop

 

MID69489 > auF12184

Cylinder cut out (rev limit etc)

 

MID63792 == 1

Output state control of LAMBSE (OBD2 tester has requested it)

 

P0152 HEGO Overvoltage

P0155 HEGO Malfunction
 

[Roland@pcmtec]

These two will force a car into open loop as well.

set auF2543 FUEL OVRD SWITCH to  1

make sure auF1545 FUEL OLCL SWITCH is set at  1

[BeerTurbo]

Howdy,

 

auF1941 LTFT Enable - if this is disabled with STFT still be active?

if there a way to reset the LTFT data? or is it done each time you flash the PCM?

 

i noticed in forscan my LTFT was at 25 percent at idle. but starting going away if i held it above idle.

at the time i was disgnosing a idle issue, thats required a replacement Throttlebody, repairs to fuel pump harness and while i was playing with pcm i played with the idle airflow table...so i proberly should put that back... but just wondered when ltft data resets.

 

 

[Roland@pcmtec]

There is not such thing as STFT it is simply the commanded lambda. 

LTFT is reset on a flash. 

[john.z]

On 11/23/2017 at 1:27 PM, Roland@pcmtec said:

UPDATE:

on FGs the best way is to just set the A/D Count to 0.0 on the Open Loop TPS Transition table auF0153 as the above tables have been reported to not work on FGs

funny thing with this is if you start the car and dont touch the throttle it will go into closed loop until you do

[Roland@pcmtec]

21 hours ago, john.z said:

funny thing with this is if you start the car and dont touch the throttle it will go into closed loop until you do

That is interesting and makes sense. 

I would simply follow every single suggestion in the thread. If you do all of the settings I can't see how it could possibly still trim. 

In every car we have tested on we can successfully disable LTFT with any of the settings on their own.

If someone has one where it will not disable and can be made available via teamviewer during business hours we can log in and see if we can figure out a concrete way to disable the trims. We can then report back how to do it on here for everyone else. 

[john.z]

2 minutes ago, Roland@pcmtec said:

That is interesting and makes sense. 

I would simply follow every single suggestion in the thread. If you do all of the settings I can't see how it could possibly still trim. 

In every car we have tested on we can successfully disable LTFT with any of the settings on their own.

If someone has one where it will not disable and can be made available via teamviewer during business hours we can log in and see if we can figure out a concrete way to disable the trims. We can then report back how to do it on here for everyone else. 

It’s no big deal, just need to touch the throttle when the car first starts so it makes no changes. Easy price to pay for only needing to change one table