HARLEY: Tuning in Closed Loop
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Intermediate
Joined: Apr 2012
Posts: 25
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From: Russia
Tuning in Closed Loop
Hi everyone,
I've looked through the forum and couldn't find any information on closed loop tuning.
My bike is 2011 Wide Glide with EFI and O2 sensors. I've installed Stage III kit on it + exhaust and air filter. I also reprogrammed the ECU with SEPST with the closest matching map I could find there. But these pre-loaded maps are not final as I understand. Rather, they ensure proper engine operation with given hardware but require some further fine tuning.
So my bike runs in Closed Loop and I intend to leave it this way. I see no point in disabling the sophisticated self-correcting mechanism.
Some tuners do the following: they put the bike in open loop, change the values in AFR tables, change VE tables and flip the bike back to Closed Loop. But is doesn't work this way, because now the ECU will always try to remove fuel to get back to 14.6 AFR. So the result of this "tuning" is overly rich map and less mileage than stock. Correct me if I am wrong, that's how I see it.
Hence the question - how to tune in Closed Loop? The main thing is to get VE tables correct, right? But in Closed Loop the underlying base map needs to be set to differing air-fuel ratios. So far I am confused and would appreciate any knowlegeable input from forum members regarding the logic and general procedure for tuning in Closed Loop.
I've looked through the forum and couldn't find any information on closed loop tuning.
My bike is 2011 Wide Glide with EFI and O2 sensors. I've installed Stage III kit on it + exhaust and air filter. I also reprogrammed the ECU with SEPST with the closest matching map I could find there. But these pre-loaded maps are not final as I understand. Rather, they ensure proper engine operation with given hardware but require some further fine tuning.
So my bike runs in Closed Loop and I intend to leave it this way. I see no point in disabling the sophisticated self-correcting mechanism.
Some tuners do the following: they put the bike in open loop, change the values in AFR tables, change VE tables and flip the bike back to Closed Loop. But is doesn't work this way, because now the ECU will always try to remove fuel to get back to 14.6 AFR. So the result of this "tuning" is overly rich map and less mileage than stock. Correct me if I am wrong, that's how I see it.
Hence the question - how to tune in Closed Loop? The main thing is to get VE tables correct, right? But in Closed Loop the underlying base map needs to be set to differing air-fuel ratios. So far I am confused and would appreciate any knowlegeable input from forum members regarding the logic and general procedure for tuning in Closed Loop.
Road Warrior
Joined: Aug 2014
Posts: 1,937
Likes: 320
From: Vancouver, WA
The way I understand it is to get your VE tables correct first by doing an auto tune. Once that's established then you can adjust your AFR from there and it'll be more accurate because of the correct VE's at each kPa and RPM. The problem though is the narrow band O2 sensors as they will only recognize a small window of AFR; something like 13.9 to 14.6 (I'd have to go back and check those numbers to be sure). Anything beyond those AFR settings will put you in open loop.
Last edited by RG Pilot; Oct 7, 2016 at 05:31 PM.
Road Captain
Joined: Jan 2014
Posts: 641
Likes: 48
From: Brisbane
https://www.rbracing-rsr.com/downloads/tts_tuning.pdf
Have a good read of this, it should clear up a lot of your questions. It's a very comprehensive guide.
'06 NT, 95", S&S .510g, V&H BR 2-2, K&N AC, P&P Heads
Have a good read of this, it should clear up a lot of your questions. It's a very comprehensive guide.
'06 NT, 95", S&S .510g, V&H BR 2-2, K&N AC, P&P Heads
Use the smart tune feature of the SEPST to adjust your VE tables. When done, set the AF back to factory if those are the settings you want.
Personally if you want to stay in closed loop, I would run the AF values to the low end of the closed loop threshold (14.3)
Personally if you want to stay in closed loop, I would run the AF values to the low end of the closed loop threshold (14.3)
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