Air Fuel Ratio maps 1,2 and 3

VersaTuner for Mazda RX-8
jojo
Posts: 3
Joined: April 20th, 2017, 3:27 am

Air Fuel Ratio maps 1,2 and 3

Post by jojo »

Hi,

does anyone already know under which conditions the ECU is using which one of the three maps?

To me it's not clear, also from the logs, which one of the maps is used for calculation of the air fuel ratio during driving.

For the Idle Speed Curves 1-7 it seem to be somehow time-based. The ECU interpolated from on curve to the next after an amount of time when the engine is running.

But for AFR time-based seems not to apply here. Could the AFR maps 1, 2 and 3 be related the different markets? Like AFR1 for Japan, AFR2 for Europe and AFR3 for the US market to reflect different emission legislation?



Regards,

Johannes.
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Steve @ VersaTune
Lead tuner
Posts: 1157
Joined: March 29th, 2010, 12:58 pm

Re: Air Fuel Ratio maps 1,2 and 3

Post by Steve @ VersaTune »

They are not for different markets. They are for specific operating conditions. We are still sorting through the AFR control logic. It is extremely complicated on RX-8s. As we learn more, we will update the table names and descriptions.
jojo
Posts: 3
Joined: April 20th, 2017, 3:27 am

Re: Air Fuel Ratio maps 1,2 and 3

Post by jojo »

Hi Steve,

this would match with my observations. I altered only the maps 2 and 3 but this did not give the results I expected.

Let me know if there is some progress when and how these operation points apply.

Johannes.
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Steve @ VersaTune
Lead tuner
Posts: 1157
Joined: March 29th, 2010, 12:58 pm

Re: Air Fuel Ratio maps 1,2 and 3

Post by Steve @ VersaTune »

For now, you can use the VE tables to alter AFRs.
jojo
Posts: 3
Joined: April 20th, 2017, 3:27 am

Re: Air Fuel Ratio maps 1,2 and 3

Post by jojo »

Hi Steve,

I din't change the VE values. I altered all 3 AFR maps during the last week more os less simultaneously.

With this tune i was able to lean the rx8 to 0.8 in hight load and rpm operations. 6500-9000rpm. with load between 0,875 and 0,98.

Unfortunately it's not clear to me when which of the map will be used. Currently I can only guess that map 1 seems to be used in 4th gear or after a certain time of high engine loads. maps 2 and 3 may apply in the lower gears.

Main problem is that I cannot see the target AFR during this operation mode, the value shown in versatune is fixed at 1.0. As soon as we can have this value living and are able to see the real ecu AFR targets it might be easier to gues the operation point for these maps.

Regards,

Johannes.
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Steve @ VersaTune
Lead tuner
Posts: 1157
Joined: March 29th, 2010, 12:58 pm

Re: Air Fuel Ratio maps 1,2 and 3

Post by Steve @ VersaTune »

That is the correct logging parameter. It's possible that the ECU does not update that PID in open loop.
hufflepuff
Posts: 3
Joined: June 27th, 2020, 3:58 am

Re: Air Fuel Ratio maps 1,2 and 3

Post by hufflepuff »

I have run into a challenge where the car is running a tad too rich at 9000 rpms (see attached data log) but i am approaching the adjustments limits of the fueling table. My excel calculations are telling me i need to enter a fueling correction of greater than 1.0.

Question is, can i lean out the car at the 9000 rpm range by using the VE table or maybe maximum operating load (absolute load)? What is recommended to take a few % of fuel out at the very top end?

Fueling between 3000 and 8500 rpms is beautiful. i am targeting ~12.8:1.

https://drive.google.com/file/d/18GUsTw ... sp=sharing
Data log

https://drive.google.com/file/d/1K6lg80 ... sp=sharing
Excel math
DSSRotard
Posts: 8
Joined: April 19th, 2020, 3:22 am

Re: Air Fuel Ratio maps 1,2 and 3

Post by DSSRotard »

hufflepuff wrote: June 28th, 2020, 6:41 am I have run into a challenge where the car is running a tad too rich at 9000 rpms (see attached data log) but i am approaching the adjustments limits of the fueling table. My excel calculations are telling me i need to enter a fueling correction of greater than 1.0.

Question is, can i lean out the car at the 9000 rpm range by using the VE table or maybe maximum operating load (absolute load)? What is recommended to take a few % of fuel out at the very top end?

Fueling between 3000 and 8500 rpms is beautiful. i am targeting ~12.8:1.

https://drive.google.com/file/d/18GUsTw ... sp=sharing
Data log

https://drive.google.com/file/d/1K6lg80 ... sp=sharing
Excel math
Maybe im late but... Have you tried the function "Allow Entering Unsafe Values" ??
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wcs
Posts: 61
Joined: May 12th, 2021, 12:46 am

Re: Air Fuel Ratio maps 1,2 and 3

Post by wcs »

Just a small bump to show there is still some interest out there for more detail on these fuel maps.

I will add I’ve just switched over from Access Tuner Race and where I was taught those tables represented 1-2 Gear 3-4 Gear and 5-6 Gear.

Ive had success tuning this way but have not scrutinized the settings with the log data to a great deal.

If there’s more to it I would love to know.
d-LoiX
Posts: 10
Joined: August 12th, 2021, 12:49 pm

Re: Air Fuel Ratio maps 1,2 and 3

Post by d-LoiX »

Really interested to confirm this, I also read it somewhere.
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