In the engine>fuel>open&closed loop there is a tab for defining stoich air fuel, in AFR (which is surprising itself seeing as the maps are all lambda)
What exactly is it meant to do?
I am trying to get some lean cruise happening, but cant get it to sit any leaner than lambda 1.
if you want leaner number you can play with the MBT tables and you can reach that lean spot with timing adjustments
Unless it's me, it seems that the base fuel table is only for open loop.
I could be wrong, but no matter what I set the values to, it still likes to sit on lambda 1, so my question now is what table does it look at for the closed loop target??
Well an F6 'generally' wont ever see MBT timing. The PCM will compare the BKT and MBT calculations and use the lower of the two.
Closed loop is...well closed loop. It's continually targeting a lambda 1.0 by 'reading' the oxygen content of the exhaust gas. SO there is no look-up table. The PCM's learning via the LTFT will make adjustments to get lambda 1 so stick in 98ron and it will toggle around 1.0.....stick in E10 and it will toggle around 1.0 but the PCM will be adding fuel via the LTFT to compensate for the lower stoich of the ethanol component.
There is a switch to disable closed loop learning....but that would be silly IMO when closed loop does it's job so well. If you want to toggle closed loop aroun 1.05 for example then i'm fairly confident this can't be done.
even at 1.0 highway cruising i used to consistantly see 9-9.4 ltrs/100
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Yeah, but it could be better, and I am sure there is a lambda look-up table that just hasn't been revealled.
Any ecu I've ever tuned that runs anything resembling closed loop control always has a look-up table
Its basicly letting the ecu know what type of fuel your using, E85 would be 9.7:1In the engine>fuel>open&closed loop there is a tab for defining stoich air fuel, in AFR (which is surprising itself seeing as the maps are all lambda)
What exactly is it meant to do?
I'm guessing closed loop would be chasing this figure.
Yeah, you'd think, but it doesnt. Changing that effects open loop only it seems
What about the OL TPS threshold. If TPS less than TPS threshold then run in closed loop.
Originally Posted by jeremy
if you set the car to run in open loop, which is what you'll be doing by modding this table, then you will defeat the purpose of trying to acheive a leaner cruise.
because you be running solely off the maf calibration and i can gurantee you it will not be tuneable to exactly the afr your trying to acheive (15.2? i suspect)
without o2 feedback you will burn unecessary fuel.
I do believe that the hp software will not allow you to mod the stoich afr ratio that the o2 sensors are looking for. I have not looked for it truthfully.
MBT table is not the place to go to try for a leaner cruise either
Roadracing Crew Chief - World Superbike, British Superbike, Moto America.
I thought Ford shoots for lambda when in closed loop and corrects what is commaned in the open fuel table if tps is less than the open loop value. The SFT and LFT are used in closed loop to corrrect for the variation form lambda. This is why setting anything different to lambda will just effect the trims and nothing else as its aim is lambda not what is commanded.
Correct. The stoich modifier should only be used when the fuel type is changed. In closed loop, the PCM will always rely on the o2 sensors, hence closed loop. By fudging the stoich modifier you will change the amount of fuel injected in open loop but the o2s will correct right back to lambda 1 of the fuel you are actually burning and you'll end up with some crazy fuel trims.
You can change the 02 bias some to run it a bit leaner while in closed loop. Can't say if HPT has these parameters though. But that is the only way I know to achieve this , short of running it in open loop, and setting the open loop fuel table to lean values.
Eric Brooks
HP Tuners, LLC
Yeah, we have:
Bias Min
Bias A vs RPM vs Load
Bank 1 vs RPM vs Load
Bank 2 vs RPM vs Load
With reference to Bank2, the table is full of Zero's.
Bank 1 and Bias A are full of info.
In non v engines bank 1 STFT are used not bank 2. I am not sure what Bias A is.
I had made some changes to both the tables to a degree of -25% and there was no obvious change to the end mixture. Bias is more a function of the sensor than anything else and I'd say no matter what you change it to, the end will always be the same.
You should have two tables.....
Closed Loop Feed Forward Bias Bank 1 and Bank 2.
With Airmass on the X axis and CAT Temp on the Y. Increasing the value will slightly lean the mixture. Its not a huge change.
Eric Brooks
HP Tuners, LLC
Here is a screen shot of what we have.
According to the 'help' description of these items, I got the impression that decreasing the bias would make it leaner - what is actually says is: "positive values are richer, negative values are leaner"
change it by 7% and see what happens, adding or subtracting 7% should make it 15.7 or 13.6.... experiment a little.
you'll see real it on the wide band if you youre cruising down the road and it's now 1 point leaner or richer.
Roadracing Crew Chief - World Superbike, British Superbike, Moto America.
Yeah, I have my trusty old Autronic wide band in the car and have made the changes 'negative' but have not had a chance to go the other way as yet. Stay tuned.........(pardon the pun!)
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