open loop fuel control

[richardpalinkas]

can you adjust the delay time/ transition rate from open loop fuel control to closed loop fuel control, say from 4000rpm above?

 

cheers

[Darryl@pcmtec]

Richard you certainly can. Open loop transition for the Australian Fords happens when the driver requests more power and Closed loop fuel control is exited. The criteria for exiting Open loop is based on Throttle Position (TP) via table auF0523. This is the default value for my car were:

Which on a turbo car with any modifications Closed Loop fuel control at reasonable high levels of boost (10psi in my case) which I was not happy with.  A/D counts are throttle position in Analogue Digital counts with values varying between 0 and 1023. Think of 0 as closed throttle and 1023 representing the throttle blade full open. You can check your tune but  the PCM considers Wide Open Throttle (WOT) as being around 590 A/D counts. To improve this my tune was changed to:

You can edit this table to get the transition to occur at what throttle position you want.

Delay Time

The Australian Falcons have a delay timer/ramp that controls the transition form Closed loop to open Loop. For the turbo car most tuners change these scalar auF0158 to around 0.5:

.

This allows for quick transition from Closed Loop to Open Loop[ fueling.

Ford of Australia seems to zero out the Open Loop Delay table so that does not play a part in the decision making for the PCM.

[Andrew]

Hey everyone. Related question - if I set the values in this table to zero, does this force open loop at idle?

[Roland@pcmtec]

On 8/19/2019 at 10:38 PM, Andrew said:

Hey everyone. Related question - if I set the values in this table to zero, does this force open loop at idle?

Good question, not sure if you can that way. Best way is to just unplug the O2 sensor or disable closed loop entirely as per this guide https://forum.pcmtec.com/topic/3-howto-disabling-closed-loop-o2/

[Andrew]

Thanks Rolls!  For some reason I didn't find that when I was searching, but it is what I need.

Before I drove home from work this arvo I set auF0523 AD to 0 across the RPM range and auF0162 to 3600 seconds (one hour) at all coolant temps.  

To be sure, I'll set AD to -100 as per your comment at the above link and set auF2504 to 4096 degrees C.

 

When troubleshooting a suspected hardware issue, it is neat to be able to use the tune to help isolate things!

[Rmrmd1956]

On 8/19/2019 at 9:08 AM, Andrew said:

Hey everyone. Related question - if I set the values in this table to zero, does this force open loop at idle?

Yes

[Roland@pcmtec]

1 hour ago, Rmrmd1956 said:

Yes

Are you sure? I've ever actually tested it at idle. 

[Rmrmd1956]

23 hours ago, Roland@pcmtec said:

Are you sure? I've ever actually tested it at idle. 

Well, in my Aston that’s how I run open loop at idle and I let it run closed loop above that until 3800. In my application idle is more even In open loop, it hunts in closed loop for some reason. Can’t guarantee it works in the Aussie code but looks very similar in IDA Pro

[Roland@pcmtec]

7 hours ago, Rmrmd1956 said:

Well, in my Aston that’s how I run open loop at idle and I let it run closed loop above that until 3800. In my application idle is more even In open loop, it hunts in closed loop for some reason. Can’t guarantee it works in the Aussie code but looks very similar in IDA Pro

Hey stranger! Now I know who I'm talking to.

Good info. I'll have to try it out on my local car, I trust your analysis.

[fordsrule]

Probably an obvious answer but if open loop is on all the time, even at idle does this mean that the pcm is going to the fuel table all the time?

Also, does the pcm still receive input from say the ect or iat?

Cheers

Steve

[Rmrmd1956]

Yes, PCM will run off the open loop fuel table when warm, in that situation. I have done that many times. PCM continues to receive and act on ECT and IAT. It often uses a weighted average of these two temps in it’s warmup tables.

 

[fordsrule]

6 minutes ago, Rmrmd1956 said:

Yes, PCM will run off the open loop fuel table when warm, in that situation. I have done that many times. PCM continues to receive and act on ECT and IAT. It often uses a weighted average of these two temps in it’s warmup tables.

 

Ok thanks for that

Steve

[Rmrmd1956]

There is also the table for open loop decel.

car will decel in open loop if the load is LESS than table value

[fordsrule]

20 minutes ago, Rmrmd1956 said:

There is also the table for open loop decel.

car will decel in open loop if the load is LESS than table value

That's handy to know, thankyou so much

[fordsrule]

On 3/16/2018 at 9:52 PM, Darryl@pcmtec said:

Richard you certainly can. Open loop transition for the Australian Fords happens when the driver requests more power and Closed loop fuel control is exited. The criteria for exiting Open loop is based on Throttle Position (TP) via table auF0523. This is the default value for my car were:

Which on a turbo car with any modifications Closed Loop fuel control at reasonable high levels of boost (10psi in my case) which I was not happy with.  A/D counts are throttle position in Analogue Digital counts with values varying between 0 and 1023. Think of 0 as closed throttle and 1023 representing the throttle blade full open. You can check your tune but  the PCM considers Wide Open Throttle (WOT) as being around 590 A/D counts. To improve this my tune was changed to:

You can edit this table to get the transition to occur at what throttle position you want.

Delay Time

The Australian Falcons have a delay timer/ramp that controls the transition form Closed loop to open Loop. For the turbo car most tuners change these scalar auF0158 to around 0.5:

.

This allows for quick transition from Closed Loop to Open Loop[ fueling.

Ford of Australia seems to zero out the Open Loop Delay table so that does not play a part in the decision making for the PCM.

I'm a bit confused with this info, if the pcm takes the value of 590 as WOT, why does your transition table show the value of 100 at 6000 rpm, asuming that you would be at WOT at 6000 rpm?

Cheers

[Rmrmd1956]

Car will transition to open loop when the throttle counts exceed the value at that RPM. So you could be tooling around in first gear revving your motor at 6000 RPM say at 30 or 40 MPH with very little accelerator input and have only a small throttle angle, if it is less than 100 counts it will fuel at lambda, in closed loop.

since WOT is at 590, you will always be open loop at WOT at any RPM in the above tables ‘cause transition count are always less than 590 in the above tables.

 

 

Edited September 25, 2019 by Rmrmd1956
More info

[fordsrule]

So, do you read it in reverse in a sense?

[Roland@pcmtec]

When the TPS is greater than the set point it commands open loop. 

[fordsrule]

9 hours ago, Roland@pcmtec said:

When the TPS is greater than the set point it commands open loop. 

I have all but the first TPS value zeroed, and it goes into open loop just above idle or just pushing on the throttle pedal.

[Rmrmd1956]

Yes, exactly

[XR655]

Has any body been able to set open loop at idle? 

Open loop works as it should when driving except on super light load conditions and idle?

TPS transition is set to 0 for all ranges and all other O2 temp and delay scalars are raised as per guide. 

[Rmrmd1956]

So, to get open loop at idle or during deceleration, with no accel pedal input, you need to adjust load for open loop during deceleration table that I posted previously. This is a correction to what I said previously.

If you just want open loop all the time and don’t want to tweak when it transitions, one easy way is to adjust the time delay for closed loop below:

Just set the right side to 10 x 60 x 60=36000 for 10 hours and you will always be in open loop. I’m sorry I don’t know how/where these tables are labeled/located in your software.

[Rmrmd1956]

Different calibrations may use slightly different algorithms so you may need to try different things.

[dat111]

just a quick question, once turning off the 02 sensors/run open loop all the time. 
with fueling will i need to redial in fueling? or will it obey the fueling base table. 

[hjtrbo]

It will obey base fuel but if your injectors are off then who knows what you'll end up with out the tail pipe as your O2 sensors are no longer correcting the injector data error.

It is a another good option to tune a car in open loop. Ideally you would have 1 in your open loop table for idle and cruise areas and (assuming turbo) 0.8 in your high load areas.

Then plot lambda from your wideband against commanded EQ. From there you would dial in your injectors so that the wideband matches the base fuel table +/- a few % in steady state driving. Then rinse and repeat on a tank of E85. There will be a few back and forwards.

After that switch on closed loop and enjoy. Now that you know your injector is as close as it will ever get then any small fuelling adjustments can be made in the VE tables for 98 and e85 tunes.

[dat111]

6 hours ago, hjtrbo said:

It will obey base fuel but if your injectors are off then who knows what you'll end up with out the tail pipe as your O2 sensors are no longer correcting the injector data error.

It is a another good option to tune a car in open loop. Ideally you would have 1 in your open loop table for idle and cruise areas and (assuming turbo) 0.8 in your high load areas.

Then plot lambda from your wideband against commanded EQ. From there you would dial in your injectors so that the wideband matches the base fuel table +/- a few % in steady state driving. Then rinse and repeat on a tank of E85. There will be a few back and forwards.

After that switch on closed loop and enjoy. Now that you know your injector is as close as it will ever get then any small fuelling adjustments can be made in the VE tables for 98 and e85 tunes.

im running the stock B series injectors on my bf NA turbo.  so im still using the stock injector data (new ones are being installed) assuming they are stock, would it obey the commanded fuel  lambda 

reason i wanted to turn off closed loop for good. so i could stick a wideband 02 sensor in the dump where the  front 02 resides (i get LSU 4.9 sensors  for a blooody good price) 

 

Edited April 2, 2022 by dat111

[hjtrbo]

It should. There are cold start modifiers that you'd leave alone. 

You'll still need a device to control the LSU 4.9. Are you open to welding in another bung and let the narrow bands do there thing? The DLP-8 is back in stock and still cheap.

[Roland@pcmtec]

They transients will always swing when in open loop. Closed loop will always be better. 

Why not drill a second bung? That's what I did when I was learning. 

[dat111]

4 hours ago, Roland@pcmtec said:

They transients will always swing when in open loop. Closed loop will always be better. 

Why not drill a second bung? That's what I did when I was learning. 

becuase im a tight arse lol. ive turned the rear 02 off, i did have it in there.. but when i pulled it out.. the sensor was can opened (the guy who did o2 bung, welded it horrible)

[Puffwagon]

It's worth having the extra bung imo. Take your dump or mid pipe into a shop and they should do it for under $100.

[Roland@pcmtec]

5 hours ago, dat111 said:

becuase im a tight arse lol. ive turned the rear 02 off, i did have it in there.. but when i pulled it out.. the sensor was can opened (the guy who did o2 bung, welded it horrible)

I got one welded in for $50 without taking the dump off the car. It's tight but not impossible to get in there.

[rfh]

On 3/16/2018 at 10:52 PM, Darryl@pcmtec said:

Richard you certainly can. Open loop transition for the Australian Fords happens when the driver requests more power and Closed loop fuel control is exited. The criteria for exiting Open loop is based on Throttle Position (TP) via table auF0523. This is the default value for my car were:

Which on a turbo car with any modifications Closed Loop fuel control at reasonable high levels of boost (10psi in my case) which I was not happy with.  A/D counts are throttle position in Analogue Digital counts with values varying between 0 and 1023. Think of 0 as closed throttle and 1023 representing the throttle blade full open. You can check your tune but  the PCM considers Wide Open Throttle (WOT) as being around 590 A/D counts. To improve this my tune was changed to:

You can edit this table to get the transition to occur at what throttle position you want.

Hey guys

I have found the A/D count to be way off on this parameter.... I have blanket changed the A/D numbers to 60, and the log shows this..

Open Loop source B1 on the bottom row TP 252 A/D, transition from closed to open loop..

Any ideas?

Thanks Rob

[Roland@pcmtec]

Closed loop is blended with a delay timer. If you set the blend timer to 0 it should be instant. 

[Puffwagon]

35 minutes ago, Roland@pcmtec said:

Closed loop is blended with a delay timer. If you set the blend timer to 0 it should be instant. 

 

I thought about that, but the stock setting is 0.1 seconds or something, and the log shows it changing to open loop in that time frame.

The tps was over 100 for about 3.5 seconds. If it was set to 60 per the previous post then it should be in open loop nearly all the time.

[rfh]

1 hour ago, Puffwagon said:

 

I thought about that, but the stock setting is 0.1 seconds or something, and the log shows it changing to open loop in that time frame.

The tps was over 100 for about 3.5 seconds. If it was set to 60 per the previous post then it should be in open loop nearly all the time.

My thoughts exactly.. Idle tps A/D is about 135

As for other scaler tweaks, they are: 

So maybe the A/d of 60 to transition to open open is a relitive measurement??

Cheers Rob

[rfh]

Just now, rfh said:

open open relitive

 

Open loop....

Relative....

Saturday nights......

[Puffwagon]

Had a look through the internet and found a file that describes "fn338" as,  "Fuel - Open loop time delay for FN338(N), sec."

Might be worth changing it.

Edited June 18, 2022 by Puffwagon