Closed loop

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tophe88
Posts: 17
Joined: May 6th, 2022, 8:31 am

Closed loop

Post by tophe88 »

Hello

Can have a full closed loop on map ?
What is the advantage to not stay in closed loop ??

REgards
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Ugnius @ VersaTune
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Joined: March 19th, 2010, 11:57 am

Re: Closed loop

Post by Ugnius @ VersaTune »

The idea of closed loop is to be able to automatically correct the engine operation based on sensor readouts. When the engine is running at high load, things are changing quicker than O2 sensors can react. There is no time to read the sensors and make adjustments, so the ECU switches to preprogrammed settings for that load/RPM (open loop). As sensors get better and ECUs get faster, closed loop is used across a wider operating range.
You can change the transition to open loop by editing Closed Loop Max Load/RPM/Throttle tables (on Gen1 RX-8). I don't think it will run well on 100% closed loop.
mituc
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Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Closed loop

Post by mituc »

I actually tested this on both gens 3MPS/Mazdaspeed 3. When running in closed loop at high loads the car response is not as sharp as when running in open loop. As Ugiuns mentioned, things happen faster at those loads that the sensors react, however the ECU will stubbornly wait for the O2 sensors input which will make the car feel not as responsive, even though it will rev and meet the load/boost targets.

At least for the 2.3DISI-T platform, including the 3MPS BL/gen2 speed3 which has a faster ECU than the 3MPS BK/gen1 speed3, 6MPS Mazdaspeed6 and the gen1 CX7, is to have the MAF vector properly and accurately calibrated to ensure minimal deviations from the AFR targets.

Also, the factory tunes including the OTS tunes run fuel corrections up to load values of 2.5. However the closed loop - open loop transition is regulated by other inputs as well (APP, load), so even when doing fuel corrections the ECU will run in open loop and will use the open loop tables. But realistically that is not 100% true open loop operation.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
tophe88
Posts: 17
Joined: May 6th, 2022, 8:31 am

Re: Closed loop

Post by tophe88 »

Ok thank you for yout reply. I understand better.
I have a last question, how the map enrichissment run please ?
mituc
VersaTuner guru
Posts: 1214
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Closed loop

Post by mituc »

tophe88 wrote: November 2nd, 2022, 1:28 am I have a last question, how the map enrichissment run please ?
You have several tables for AFR targets, why not use those?
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
tophe88
Posts: 17
Joined: May 6th, 2022, 8:31 am

Re: Closed loop

Post by tophe88 »

Just for know how it work.

When i have 3 tables for AFR or timing
its for 1-2 3-4 5-6 speed ?
Because when i change some value in one table, he does the same thing in other speed
mituc
VersaTuner guru
Posts: 1214
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Closed loop

Post by mituc »

tophe88 wrote: November 7th, 2022, 12:23 am When i have 3 tables for AFR or timing
Depending on the platform these tables may differ, but in general:
- for timing you have a normal table, an overload table and a max table.
- for AFR you have a closed loop, partial throttle open loop and WOT open loop.

On RX8s you have different timing tables for the leading and trailing spark plugs. For AFR you will have 4 tables which the ECU logic will look up in different situations (which ones is unclear yet, so keep them consistent). There is no ignition or AFR table per gear, that is 100% sure.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
tophe88
Posts: 17
Joined: May 6th, 2022, 8:31 am

Re: Closed loop

Post by tophe88 »

Mmm thank you for your reply.
So its explain why its always the same thing in different gear

Its a guy that he say me that is speed...
And for me i have only 3 table for AFR + afr ratio

So on rx8 its not "for AFR you have a closed loop, partial throttle open loop and WOT open loop." ?

If unclear ?
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