2bar SD tune + CL
Thread Starter
Launching!
Joined: Sep 2004
Posts: 246
Likes: 0
2bar SD tune + CL Okay, I am about to do a 2bar SD tune in HPT on a supercharged 408 vette. I understand the need to disable closed loop and ltft learning and all the VE adjustments I need to make. I will be using a wideband and going off afr% error.
1. My question is...since I am no longer going to be using a MAF, is it a good idea to at least re-enable closed loop once I am done with the full VE tuning? Or for this type of car would it just be better to leave it in full time open loop?????????? The car will be daily driven and driven in diff climates. From what I understand, a properly tuned VE table in conjunction with the IAT sensor, will fully adjust to temp changes
2. Also, something I am a bit confused about is the need to the boost enrichment or PE table when doing 2bar SD? If I have the ability to tune the car for ANY MAP then why would I need PE? If I wanted to use PE, wouldnt I just be fine with the 1bar map sensor??? What is the point of entering PE mode when you have a VE table that will adjust hard coded fueling up to 2bar or 3bar?
1. My question is...since I am no longer going to be using a MAF, is it a good idea to at least re-enable closed loop once I am done with the full VE tuning? Or for this type of car would it just be better to leave it in full time open loop?????????? The car will be daily driven and driven in diff climates. From what I understand, a properly tuned VE table in conjunction with the IAT sensor, will fully adjust to temp changes
2. Also, something I am a bit confused about is the need to the boost enrichment or PE table when doing 2bar SD? If I have the ability to tune the car for ANY MAP then why would I need PE? If I wanted to use PE, wouldnt I just be fine with the 1bar map sensor??? What is the point of entering PE mode when you have a VE table that will adjust hard coded fueling up to 2bar or 3bar?
1. first get it going in OL and SD. once dialed in, try to turn on CL and see if it behaves. if it does, great, you have a bit more flexibility, if not, you'll just have to monitor it closely in OL.
2. you're right, it's not exactly clear on why we'd have yet another table that deals with 'power' AFR, we could set it up already with OLFA, PE, and now with Boost. The real difference is what they're referenced off--OLFA has ECT, PE has RPM, and Boost has MAP. PE might have a problem if you get boost at different RPMs in different gears (turbos afterall are load-dependent, thus gear sensitive). Boost doesn't have that problem, but it doesn't know about RPM either. So it really depends what your problem is. Set it to something safe and go out logging for difference scenarios, look at the logs, see if it goes into OL/PE at the proper moment. I've seen boost on car at 1800rpm and <30%TPS, which is quite a different setting than what they give you from factory, and you dont wanna have full boost at stoichiometric ratios.
2. you're right, it's not exactly clear on why we'd have yet another table that deals with 'power' AFR, we could set it up already with OLFA, PE, and now with Boost. The real difference is what they're referenced off--OLFA has ECT, PE has RPM, and Boost has MAP. PE might have a problem if you get boost at different RPMs in different gears (turbos afterall are load-dependent, thus gear sensitive). Boost doesn't have that problem, but it doesn't know about RPM either. So it really depends what your problem is. Set it to something safe and go out logging for difference scenarios, look at the logs, see if it goes into OL/PE at the proper moment. I've seen boost on car at 1800rpm and <30%TPS, which is quite a different setting than what they give you from factory, and you dont wanna have full boost at stoichiometric ratios.
Thread Starter
Launching!
Joined: Sep 2004
Posts: 246
Likes: 0
Originally Posted by RedHardSupra
1. first get it going in OL and SD. once dialed in, try to turn on CL and see if it behaves. if it does, great, you have a bit more flexibility, if not, you'll just have to monitor it closely in OL.
2. you're right, it's not exactly clear on why we'd have yet another table that deals with 'power' AFR, we could set it up already with OLFA, PE, and now with Boost. The real difference is what they're referenced off--OLFA has ECT, PE has RPM, and Boost has MAP. PE might have a problem if you get boost at different RPMs in different gears (turbos afterall are load-dependent, thus gear sensitive). Boost doesn't have that problem, but it doesn't know about RPM either. So it really depends what your problem is. Set it to something safe and go out logging for difference scenarios, look at the logs, see if it goes into OL/PE at the proper moment. I've seen boost on car at 1800rpm and <30%TPS, which is quite a different setting than what they give you from factory, and you dont wanna have full boost at stoichiometric ratios.
2. you're right, it's not exactly clear on why we'd have yet another table that deals with 'power' AFR, we could set it up already with OLFA, PE, and now with Boost. The real difference is what they're referenced off--OLFA has ECT, PE has RPM, and Boost has MAP. PE might have a problem if you get boost at different RPMs in different gears (turbos afterall are load-dependent, thus gear sensitive). Boost doesn't have that problem, but it doesn't know about RPM either. So it really depends what your problem is. Set it to something safe and go out logging for difference scenarios, look at the logs, see if it goes into OL/PE at the proper moment. I've seen boost on car at 1800rpm and <30%TPS, which is quite a different setting than what they give you from factory, and you dont wanna have full boost at stoichiometric ratios.
Also, the guide for SD tuning says to set the entire OLFA table to 1.0 to create 14.7 across the board...but instinctively I feel like I should set the higher MAP values a little more fat. What do you think?
i wouldn't call them backups, they work differently. what you're talking about i think is the fact that when PCM gets to pick between OLFA/PE it picks the richer one. now with the addition of the boostPE vs MAP table, i dont know if the same 'richer wins' rule applies.
as for the guides telling you to set OLFA to 1.0, i think it's not only wrong but also dangerous. i leave it alone, unless there's idling issues and car needs a richer ratio to stay alive, but that's a big cam issue, not a FI issue. unless you have full understanding and a serious need for it, i'd leave OLFA alone and use it as a 'backup' just in case PE/boostPE fails to kick in. do you really want to be on boost and 14.62AFR?
as for the guides telling you to set OLFA to 1.0, i think it's not only wrong but also dangerous. i leave it alone, unless there's idling issues and car needs a richer ratio to stay alive, but that's a big cam issue, not a FI issue. unless you have full understanding and a serious need for it, i'd leave OLFA alone and use it as a 'backup' just in case PE/boostPE fails to kick in. do you really want to be on boost and 14.62AFR?
Thread Starter
Launching!
Joined: Sep 2004
Posts: 246
Likes: 0
Originally Posted by RedHardSupra
i wouldn't call them backups, they work differently. what you're talking about i think is the fact that when PCM gets to pick between OLFA/PE it picks the richer one. now with the addition of the boostPE vs MAP table, i dont know if the same 'richer wins' rule applies.
as for the guides telling you to set OLFA to 1.0, i think it's not only wrong but also dangerous. i leave it alone, unless there's idling issues and car needs a richer ratio to stay alive, but that's a big cam issue, not a FI issue. unless you have full understanding and a serious need for it, i'd leave OLFA alone and use it as a 'backup' just in case PE/boostPE fails to kick in. do you really want to be on boost and 14.62AFR?
as for the guides telling you to set OLFA to 1.0, i think it's not only wrong but also dangerous. i leave it alone, unless there's idling issues and car needs a richer ratio to stay alive, but that's a big cam issue, not a FI issue. unless you have full understanding and a serious need for it, i'd leave OLFA alone and use it as a 'backup' just in case PE/boostPE fails to kick in. do you really want to be on boost and 14.62AFR?
By Backup I mean..if it reaches a particular VE MAP cell and for some reason fails to ENTER PE, it will be ready to feed that extra fuel that would have otherwise been added by PE. Does that make sense? I know the PE is enter via a coded kpa and tps anyway, but you never know...
I havent seen the boostPE table yet, as I am still waiting for my licensing bc HPT is very slow right now trying to catch up on stuff after being at SEMA. Does it have rows for all MAP levels? Or is it just another 2-d table? I assume it has multiple rows for all kpa.
it has nothing to do with NA or FI or spray, they all become 'dangerous' at one point at stoichiometric, as they just provide you with a lot of compression. looking at my stockish (aka run it as GM intended) scans i see PE mode being triggered at around 0.35g/cyl which is not much power at all. if you have FI you're gonna hit that 'danger' value much quicker. so turning off PE for NA applications (many of which can hit 2-3 TIMES more than 0.35g/cyl) make no sense to me at all either.
boostPE is just PE dividers set along MAP axis going from 105-210kPa (for 2bar), so you can set your AFR based on how much you're boosting. i would really like to know how does it 'pick' which PE value it's going to use. if it's for example at 3000rpm and you get 5psi, does it go off OLFA, PE, or boostPE, since they call can be different? we could really use one table, just with multiple axis, so we can set target AFR per gear, per rpm, per MAP/boost, per speed (traction control basically), some better piggyback computers like Greddy E-manage can do that <hint hint, nudge nudge toward EFI/HPT guys...>
boostPE is just PE dividers set along MAP axis going from 105-210kPa (for 2bar), so you can set your AFR based on how much you're boosting. i would really like to know how does it 'pick' which PE value it's going to use. if it's for example at 3000rpm and you get 5psi, does it go off OLFA, PE, or boostPE, since they call can be different? we could really use one table, just with multiple axis, so we can set target AFR per gear, per rpm, per MAP/boost, per speed (traction control basically), some better piggyback computers like Greddy E-manage can do that <hint hint, nudge nudge toward EFI/HPT guys...>
TECH Enthusiast
Joined: Sep 2004
Posts: 564
Likes: 0
From: Omaha, NE
Also, I personally disable LTFTs but leave STFTs active while tuning. It is much easier to monitor these trims for idle and cruise and they have no affect on WOT tuning. If the STFT indicates +6%, just add +6%, or a little more if you eventually want your LTFTs to be slightly negative, to that area of your VE table. Another thing I don't understand about some tuning guides is, why do they turn off DFCO, isn't that a good thing for fuel mileage? Maybe someone can enlighten me.
Trending Topics
TECH Fanatic
Joined: Aug 2005
Posts: 1,691
Likes: 1
From: Sunny London, UK
Yes DFCO is good for mileage but if you are running a wideband and logging dfco can mess your tables up. Turn it on after tuning for sure. Otherwise your average error in dfco cells will be out.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
