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Closed loop corrections

PostPosted: Fri Jan 17, 2020 4:54 pm
by aleksanderk
Hi!
I have a S80 Pro in my Volvo, and was wondering if closed loop ambda corrections are being applied when running without the laptop connected.
The manual is a bit unclear about that, but if I understood it right, the corrected values are being applied on key cycle.

Re: Closed loop corrections

PostPosted: Fri Jan 17, 2020 5:16 pm
by stevieturbo
If you have closed loop fueling turned on, then it will be making corrections/adjustments all the time. It is always either off or on, selected either in the software or the manual switch

But it sounds like you're asking something else, or thinking about something else.

Re: Closed loop corrections

PostPosted: Fri Jan 17, 2020 8:08 pm
by aleksanderk
No, I think we are on the same page.
I run closed loop corrections, but wanted to know if it requires a PC to be connected for the corrections to take effect.

I've just been out test driving and it doesn't look like the corrections are applied until the key is off, og i apply them manually via DTASwin. So to narrow my question down a bit more; Will the closed loop corrections takke effect when driving without a PC connected, and if so - when is it applied?

Re: Closed loop corrections

PostPosted: Sat Jan 18, 2020 3:40 am
by Rob Stevens
The corrections are not automatically saved in the fuel map, the corrections are recorded in a separate table in the lambda page for the user to review. It's up to the user to decide if those corrections are creditable and then apply them to the main map. As Stevie says closed loop is controlled by the software settings or switch with additional controls like water temp, and will be constantly making corrections, it makes no odds if the pc is connected, other than the corrections are recorded on another screen on the PC for the benefit of S40 users where they have no recording facility. Key cycle does nothing. But treat the recorded fuel corrections with caution.

Re: Closed loop corrections

PostPosted: Sat Jan 18, 2020 6:04 am
by stevieturbo
aleksanderk wrote:No, I think we are on the same page.
I run closed loop corrections, but wanted to know if it requires a PC to be connected for the corrections to take effect.

I've just been out test driving and it doesn't look like the corrections are applied until the key is off, og i apply them manually via DTASwin. So to narrow my question down a bit more; Will the closed loop corrections takke effect when driving without a PC connected, and if so - when is it applied?


You seem to be talking about the fuel correction map which is software/laptop based, and a different feature than closed loop corrections.

And closed loop corrections/adjustments are applied all the time if this feature is turned on, within the +/- range you have allowed.

Obviously this does not change the actual base map. It just corrects within your adjustment range from the base map whilst driving.

Re: Closed loop corrections

PostPosted: Sat Jan 18, 2020 9:35 am
by katana
ie. the ECU is NOT self learning - you still have to correct the maps based on logged evidence.

Re: Closed loop corrections

PostPosted: Sun Jun 07, 2020 5:24 pm
by aleksanderk
I want to continue this thread a bit further, since I can't seem to figure out my closed loop settings.
I had a long drive today (About 120 kilometers) and wanted to make my map smoother since it is over all pretty good, but with some variations that I would like to get rid of.

Had my laptop on the passenger seat, with the correction table open along with the main mapping display.
Closed loop correction are allowed to change fuelling by +/- 3%. My lambda is a Innovate MTX-L, placed approx. 30cm from the turbo outlet.

It seems like the correction map records the opposite of what the lambda correction actually does.
If closed loop corrects by -3% it will register in the correction map as +3%, or very often nothing is recorded at all.
On light load/very little throttle, around 20-35Kpa no corrections are made at all when rpm is higher than idle.
Overrun throttle posision is set to 1%, and overrun rpm is set to 1000. Engine idles at 750rpm. I usually coast at 1-3%TPS@70-80km/h.

I have tried changing PID from the default 200/0/0, and are now using 310/10/10 as found on the forums. I feel that this has helped, but it might just be wishful thinking.

I'm sure that I'm not the only one having problems with this, and I'm quite sure that the fix is simple. I'm just too inexperienced to know what I'm doing wrong :lol:

Re: Closed loop corrections

PostPosted: Tue Jun 09, 2020 3:51 am
by Rob Stevens
A 3% correction isnt worth the bother! Dont forget that the corrections are only recorded if they are just about central to the current cell. You can adjust the correction window with say a 200 rpm band or tps% it's probably this feature that is leading to your odd experience. On the road it is very hard to hit the cell spot on.
I try and do the following.
Hold the throttle at a steady 10% in a gear central to your rpm set points, cell. Then left foot brake to slowly reduce the rpm, this will allow fairly accurate correction recording, then release the brake and slowly let the rpm build in the same way. Using different gears allows access to much of the low power areas of the map. With different TPS positions also.

Re: Closed loop corrections

PostPosted: Tue Jun 09, 2020 10:32 am
by aleksanderk
Rob Stevens wrote:A 3% correction isnt worth the bother! Dont forget that the corrections are only recorded if they are just about central to the current cell. You can adjust the correction window with say a 200 rpm band or tps% it's probably this feature that is leading to your odd experience. On the road it is very hard to hit the cell spot on.
I try and do the following.
Hold the throttle at a steady 10% in a gear central to your rpm set points, cell. Then left foot brake to slowly reduce the rpm, this will allow fairly accurate correction recording, then release the brake and slowly let the rpm build in the same way. Using different gears allows access to much of the low power areas of the map. With different TPS positions also.



I know that a 3% correction isn't worth it, but that's just my correction limit. Some cells need way more than 3%, but I want to get the slowly.
Some time ago I tried 15% allowed correction but that just made things waaay worse.

Thanks for the tip about increasing allowed rpm band. That's set to 100 if I remember correctly.
MAP table increase by 250rpm per row, so increasing allowed band might help.

Re: Closed loop corrections

PostPosted: Tue Jun 09, 2020 12:42 pm
by Rob Stevens
That will help capture a number, but it is more likely to be wrong!
I can run 40% corrections and its fine.