Maximum calculated load - what it does and how to override it .
Driving my unreliable rx8
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From: Alvarado, Tx
Ya, setting the tables artificially low will reduce the maximum load that can be calculated, a ceiling if you will, but artificially increasing does not increase the load calculated, it simply raises the ceiling of the load that CAN be calculated. It doesn't make it calculate more load if the load isn't actually there.
So by removing your Baro sensor you effectively removed the limit imposed by your specific elevation. Which isn't necessarily a bad thing. If the max load that can be calculated is say 200 but your actual load is 220 then your timing is going to be further advanced than you are targeting. I think it is more applicable NA where we are relying on atmospheric pressure to push air in. Not so much FI where it is being forced in. My thoughts
I have driven my car with no MAF before and it drove well, but with The calc max load table raised to 200 and the sensor unplugged it was almost impossiable to drive.
n3rd
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From: in my mind
Interesting. I drove with the MAF disconnected by mistake once after installing my CAI and it ran horribly. That was how I figured out it was disconnected, it would barely idle and couldn't accelerate to drive down my street. This was when NA before I even had a Cobb.
Driving my unreliable rx8
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From: Alvarado, Tx
As another thought Let me look through my logs better. I just ran my car without the MAF and I still saw g/sec on the cob.??????
Last edited by logalinipoo; Oct 13, 2013 at 09:08 PM.
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Ok I just did a few experiments.
Calc load 50% from 2500 to redline
I logged 48% max, then unpluged the bario and logged 53%.
It drove okay, I could flatline it at the max, then still accelerate moderiately.
Heavy acceleration to WOT would cause the WB02 to peg at 20, timing did not look bad. The injectors never went over 50% duty cucle.I think it was a fuel cut due to too much differance in the calculated load.
With just the MAF unpluged I would see 48% load at wot and it appered that it was based on throttle position.
With MAF and Bario unpluged I would see 53% load at WOT and again it appered to calc load by throttle position.
I did the same experiment with 75% Max calc load. The car seamed to run fine, but the but dyno felt some losses. With the bario it was a little low, without it was high. With MAF unpluged It seamed like load was calculated by throttle position.
Then the same experiment with 200% load.
My load was a little higher then I am used to seeing, but I think that's because I'm ported and have been limited, with the increase I am not limited.
Bario sensor unpluged the load was a little higher with it pluged in it was a little lower.
When I unpluged the MAF
I was able to get loads up to 203% at WOT.
As long as I kept the load below 100% it drove okay but very rich.
When I got my load over 125% it would bog bad.
With the bario and MAF unpluged It would barely run, but once I got it rolling I saw no differance.
Calc load 50% from 2500 to redline
I logged 48% max, then unpluged the bario and logged 53%.
It drove okay, I could flatline it at the max, then still accelerate moderiately.
Heavy acceleration to WOT would cause the WB02 to peg at 20, timing did not look bad. The injectors never went over 50% duty cucle.I think it was a fuel cut due to too much differance in the calculated load.
With just the MAF unpluged I would see 48% load at wot and it appered that it was based on throttle position.
With MAF and Bario unpluged I would see 53% load at WOT and again it appered to calc load by throttle position.
I did the same experiment with 75% Max calc load. The car seamed to run fine, but the but dyno felt some losses. With the bario it was a little low, without it was high. With MAF unpluged It seamed like load was calculated by throttle position.
Then the same experiment with 200% load.
My load was a little higher then I am used to seeing, but I think that's because I'm ported and have been limited, with the increase I am not limited.
Bario sensor unpluged the load was a little higher with it pluged in it was a little lower.
When I unpluged the MAF
I was able to get loads up to 203% at WOT.
As long as I kept the load below 100% it drove okay but very rich.
When I got my load over 125% it would bog bad.
With the bario and MAF unpluged It would barely run, but once I got it rolling I saw no differance.
I kinda feel that we failed in that you felt you had to do all this testing when the answers were all here in the thread ?
n3rd
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From: in my mind
Driving my unreliable rx8
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From: Alvarado, Tx
Nah no Fail, It was a good excuse for me to go drive around and try some new changes to my tune. I wanted to see it for myself.
I like to make one change at a time then Drive around for a while and see how it's running before I change something else.
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From: Y-cat-o NZ
Just to add to this . The tests Logalini did prompted me to try a little test of my own which confirmed his findings .
With this in mind I reset the max calc load table in the low rpm ranges to stock . Previously (when set to 200 at idle/low rpm), if i had unplugged my maf the engine would stall . Now with it set to stock .... it doesn't .
So the Max calc load table enables the ECU to find an AFR that will 'get you home' if your maf stops working . I still think it helps protect the cat as well .
This doesn't change anything from my first post but does seem to confirm that the table can be useful - even on an FI car .
With this in mind I reset the max calc load table in the low rpm ranges to stock . Previously (when set to 200 at idle/low rpm), if i had unplugged my maf the engine would stall . Now with it set to stock .... it doesn't .
So the Max calc load table enables the ECU to find an AFR that will 'get you home' if your maf stops working . I still think it helps protect the cat as well .
This doesn't change anything from my first post but does seem to confirm that the table can be useful - even on an FI car .
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From: South Wales, UK
First off guys thanks for all the info here and in the other tuning threads - I have been reading up for hours on end.
I have recently set about tuning with mazdaEdit after rebuilding my engine. I got as far as disabling some CELs and increasing the dwell for d585 coils, and noticed the calculated load maxing out in my logs:
It's not a clean full WOT run but enough to see it getting to 100% and staying there:
You can also see that when this happens the AFR bounces back up again to the 12s where it would normally be 11, which falls line in with what I have read here.
So if you will, could you confirm this is the effect of the stock load_max table? And am I now getting this because of the porting, or does this happen on standard engines too?
Thanks
Phil
I have recently set about tuning with mazdaEdit after rebuilding my engine. I got as far as disabling some CELs and increasing the dwell for d585 coils, and noticed the calculated load maxing out in my logs:
It's not a clean full WOT run but enough to see it getting to 100% and staying there:
You can also see that when this happens the AFR bounces back up again to the 12s where it would normally be 11, which falls line in with what I have read here.
So if you will, could you confirm this is the effect of the stock load_max table? And am I now getting this because of the porting, or does this happen on standard engines too?
Thanks
Phil
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From: Y-cat-o NZ
Yes , porting will cause this to happen . Just multiply all the values from 4000 and up by 10% and that will take care of it . You can then massage the numbers in the fuel maps to get what you want .
Driving my unreliable rx8
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From: Alvarado, Tx
I guess it has something to do with the sensor being unplugged. I'll do a little more testing when I get the chance.
If you look back. With the MAF plugged in. When I was testing this I would set my Max calc load at 50% and with the stock bario scale it was limiting me to 48% but when I unplugged the bario sensor I would get as high as 53% even though My calc load max scale was set for 50%.
I did this at several differant load settings and saw the same results.
Edit:
I even did 200% max calc load and 1.5 across the board on the bario. That with both sensors unplugged would give me 300% load.
Last edited by logalinipoo; Jan 20, 2014 at 02:38 PM.
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From: Y-cat-o NZ
But for Cobb tunes ... that is a good idea in that you retain that feature of being able to unplug the maff and still be able to idle etc.
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I guess it has something to do with the sensor being unplugged. I'll do a little more testing when I get the chance.
If you look back. With the MAF plugged in. When I was testing this I would set my Max calc load at 50% and with the stock bario scale it was limiting me to 48% but when I unplugged the bario sensor I would get as high as 53% even though My calc load max scale was set for 50%.
I did this at several differant load settings and saw the same results.
Edit:
I even did 200% max calc load and 1.5 across the board on the bario. That with both sensors unplugged would give me 300% load.
If you look back. With the MAF plugged in. When I was testing this I would set my Max calc load at 50% and with the stock bario scale it was limiting me to 48% but when I unplugged the bario sensor I would get as high as 53% even though My calc load max scale was set for 50%.
I did this at several differant load settings and saw the same results.
Edit:
I even did 200% max calc load and 1.5 across the board on the bario. That with both sensors unplugged would give me 300% load.
The baro sensor itself has no direct effect on fueling .
Driving my unreliable rx8
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From: Alvarado, Tx
LOL, Just found this. As usual MM gave some good info in his special way. But sadly it was basically what was discussed here.
https://www.rx8club.com/series-i-eng...4/#post2885483
https://www.rx8club.com/series-i-eng...4/#post2885483
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LOL, Just found this. As usual MM gave some good info in his special way. But sadly it was basically what was discussed here.
https://www.rx8club.com/series-i-eng...4/#post2885483
https://www.rx8club.com/series-i-eng...4/#post2885483
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If you set the values at lower than those in the fueling tables .... it will use the value in the "throttle fuel" table. If the values are higher than the fuel tables they are ignored .
I've played with them a lot but could never get the kind of effect you might get from an accelerator pump on boost transition.
Last edited by Brettus; May 26, 2015 at 01:24 AM.
Driving my unreliable rx8
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From: Alvarado, Tx
by fueling tables do you mean closed loop or open
HUMM, I wonder if they are used when the MAF is not working. Since it's based on throttle position.
HUMM, I wonder if they are used when the MAF is not working. Since it's based on throttle position.
Last edited by logalinipoo; May 26, 2015 at 01:24 AM.
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Driving my unreliable rx8
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From: Alvarado, Tx
Another table that doesn't work anything like how it has been described .
If you set the values at lower than those in the fueling tables .... it will use the value in the "throttle fuel" table. If the values are higher than the fuel tables they are ignored .
I've played with them a lot but could never get the kind of effect you might get from an accelerator pump on boost transition.
If you set the values at lower than those in the fueling tables .... it will use the value in the "throttle fuel" table. If the values are higher than the fuel tables they are ignored .
I've played with them a lot but could never get the kind of effect you might get from an accelerator pump on boost transition.
I'll do some testing when I get home, but I just reread this and it sounds exactly like how the load limiters work.
If you set the multiplier lower then your desired number it goes to the lower number. If you set it higher then it goes with whatever you have set in the other table.
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Some additional info I discovered today :
In Mazdaedit there are is one parameter named 'absolute engine load' and another 'calculated engine load' .
'Absolute engine load' is the actual load used by the ecu to calculate fuel .
The 'Calculated engine load' parameter is actually the ratio of 'absolute engine load' over the number on the 'max calc. load' table . It's a % and can't be more than 100%.
If calc. engine load goes to 100% ...... you know you have hit the max.calc. load cieling and you will run leaner than intended.
Quite a handy parameter to monitor now that i know what it is .
In Mazdaedit there are is one parameter named 'absolute engine load' and another 'calculated engine load' .
'Absolute engine load' is the actual load used by the ecu to calculate fuel .
The 'Calculated engine load' parameter is actually the ratio of 'absolute engine load' over the number on the 'max calc. load' table . It's a % and can't be more than 100%.
If calc. engine load goes to 100% ...... you know you have hit the max.calc. load cieling and you will run leaner than intended.
Quite a handy parameter to monitor now that i know what it is .
Last edited by Brettus; Feb 21, 2016 at 08:46 PM.
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How can we get around this 200% limit?
The Baro compensation map is only used by the ECU in this calculation for 'max. calculated load' . It does nothing to the actual calculated load values that determine how much fuel is injected .
So : Set all the values on this map to a value more than 1 and the max. calc. load available to you is multiplied by that number . You can set it as high as you like .
With baro comp set to 1.5 and max calc load set to 200 - the new max calc load is 1.5x200= 300%
Edit : Further to this it has been found that this map is actually referenced when there is a faulty/disconnected MAF . So if you ensure that under normal use your loads don't exceed max. calc. but keep it reasonably close to actual .............. the car will still run ok (if a little rich) until you can fix the problem.
The Baro compensation map is only used by the ECU in this calculation for 'max. calculated load' . It does nothing to the actual calculated load values that determine how much fuel is injected .
So : Set all the values on this map to a value more than 1 and the max. calc. load available to you is multiplied by that number . You can set it as high as you like .
With baro comp set to 1.5 and max calc load set to 200 - the new max calc load is 1.5x200= 300%
Edit : Further to this it has been found that this map is actually referenced when there is a faulty/disconnected MAF . So if you ensure that under normal use your loads don't exceed max. calc. but keep it reasonably close to actual .............. the car will still run ok (if a little rich) until you can fix the problem.
LE I was wrong.
Last edited by ciprianrx8; Nov 12, 2023 at 11:59 AM.