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I'm looking at getting a p01 tuned (which doesn't support flex fuel tables) to straight e85. It's going to be a street/strip car, so I do want to be able to run pump e85, which where I'm at isn't consistently e85. It's a forced induction set-up and a P59 swap won't work because of the crap table resolution. I don't want to do a standalone yet (I will eventually if I keep the car long enough).1
From what I've read, my understanding is that the knock resistance from e60 and higher is the same so the timing doesn't change after e60. I get that without flex fuel, the stoich won't change if I put in anything less than e85 (e.g., e70). However, I'm wondering if I run it on closed loop with the narrow band o2 sensors, will it get close to the target AF ratio with fuel from e60-e84? Or will it always run rich at idle and lower rpms? If it's the former, and the o2's can't adjust down to e60, or how low of ethanol content can I go while still getting close to target AF ratio (probably around stoich for e85, which I believe is 9.8:1).
Obviously, it'll run rich when it goes into open loop for WOT (or cold start), but that's not really a big deal as I plan to run actual e85 (or real close to it at the track).
I'm curious what P59 tables are inferior to any P01 tables?
To your question though, the O2 trims can swing 25% in either direction so there may well be enough there depending on how good the tune is. Only question then is WOT. Don't quote me, but I believe at WOT the PCM will add fuel if there are positive trims and leave it alone if there are negative trims, so in theory that would mean if you tune for E70 it should be leaner at E85. But you could just fudge your WOT AFR by .7 or so and be pig rich everywhere else. I feel like there are a number of folks running EXx Without flex capability in a number of platforms not blowing their junk up, I just can't speak to what extent of a compromise it is having never done it myself.
I'm curious what P59 tables are inferior to any P01 tables?
To your question though, the O2 trims can swing 25% in either direction so there may well be enough there depending on how good the tune is. Only question then is WOT. Don't quote me, but I believe at WOT the PCM will add fuel if there are positive trims and leave it alone if there are negative trims, so in theory that would mean if you tune for E70 it should be leaner at E85. But you could just fudge your WOT AFR by .7 or so and be pig rich everywhere else. I feel like there are a number of folks running EXx Without flex capability in a number of platforms not blowing their junk up, I just can't speak to what extent of a compromise it is having never done it myself.
My understanding is that the P59 has bad table resolution, which might be fine on a basic n/a car, but on a car like this one scaling 24 llbs of boost wouldn't work (it's too much to cram into the small tables). P01 has a lot better resolution making tuning it possible without a standalone (even though it's still not great).
That's good to know. So it sounds like the narrow band o2's will allow it correct at idle and while cruising (closed loop). In that case it'd make the most sense to tune it to e85 and letting us run rich at WOT when ethanol content drops rather than the other way around (if it's tuned at, e.g., e70, it'll run too lean at e85). I wouldn't go WOT at below e70 anyway (especially at high boost).
Any idea of what minimum ethanol content I could run while still getting it to target AFR in closed loop (e.g., e60, e70)?
Which tables? I have both PCMs and a lack of resolution was not something that struck me, but I guess I've never laid eyes on a COS for the P59 since the Z06 isn't boosted. Been meaning to flash it on though just because.
Honestly, I know pretty little about tuning but couldn't find anyone willing to do a P59 swap and tune on it--only heard tuners say bad things about the P59. People/shops were willing to do it on a P01 (or a standalone). This car's pretty extreme, though, for a stock PCM.
Anyone know how low of ethanol content that 25% the narrow band O2 sensors would allow the p01 PCM to adjust in closed loop (e.g. e60, e70), assuming it's tuned for e85? I know there's tables showing the different stoich points for the fuel mixes but I'm not sure how to calculate that into percentages to figure out what the lowest ethanol content I could run at target AF would be.
I was thinking about this more, and open loop at WOT isn't going to matter that much on the street with this car (it's not like it'll be able to go WOT on the street without flying into something without softening up the suspension a lot, which probably isn't worth the time--it's easier to just leave it dialed in for the drag strip). At the track, I have no plans of running anything much below e85.
If it can do closed loop on pump e85 (which isn't consistent) without it running excessively rich, I'd be happy. Just trying to figure out what the lowest ethanol content (e.g. e60, e70, etc) the narrow band o2's can adjust to hit target AF ratio if tuned for straight e85 (no flex).
The o2 sensors read lamda, they don’t care which fuel, so it will tune its self just like on pump gas. I think you can get upwards of 30% on closed loop, u can get it to take the adjustment into closed loop per a setting in the rom. It should work, we have flex fuel figured out pretty well too tho.
The o2 sensors read lamda, they don’t care which fuel, so it will tune its self just like on pump gas. I think you can get upwards of 30% on closed loop, u can get it to take the adjustment into closed loop per a setting in the rom. It should work, we have flex fuel figured out pretty well too tho.
So if it's tuned for straight e85, would 30% get it to lambda if I put in e60? If not, what's the lowest ethanol content to get it to lambda? (For example, say lambda is set for 1.0 and it's tuned for e85 (e.g., 9.8:1 stoich), and I put in e60, would the 30% fuel adjustment be enough to get the o2's back to lambda?)
Just think in lambda, not afr, it will help when dealing with diff fuels. 30% is more than enough to get you to e60. If this is your plan I’d tune it to the middle of what they get. If it goes from e60-85 I’d tune it for e70, tho these are not big changes. I think it will be fine, just log it and see, look at your o2 % change allowed settings. Make sure it is set to allow long term trims into open loop.
Just think in lambda, not afr, it will help when dealing with diff fuels. 30% is more than enough to get you to e60. If this is your plan I’d tune it to the middle of what they get. If it goes from e60-85 I’d tune it for e70, tho these are not big changes. I think it will be fine, just log it and see, look at your o2 % change allowed settings. Make sure it is set to allow long term trims into open loop.
Gotcha. So could I tune it for e70 closed loop and then e85 on open loop (PE)? The issue with tuning it for e70 on open loop would obviously be that without correction, it would run lean when I actually run e85 at WOT.
If it were my money I'd get very specific info on why folks don't like the P59. I can't fathom why a newer faster better PCM would be seen as inferior. Ask which tables lack resolution. I wonder if you didn't just misunderstand what the tuner told you?
Here's the diff between P01 and P59 3 bar OS on hptuners. You get about double the table size on P01. P59 appears to keep the stock dimensions, so you lose some resolution. Are you actually going to fine tune each cell to that level of detail? Probably not, I suspect the P59 would work just fine, honestly.
I looked at EFILive COS for P59 and it is more like P01 on HPT-- you get 2x the VE table size. Another option.
One of the biggest downsides of stock PCM on such a setup vs a standalone is the lack of full time (dual) wideband control. I don't think the diff in VE table size is as significant as this shortcoming.
With that in mind, trusting the narrowbands and LTFT to correct WOT fueling with boost just sounds like a disaster to me. If you want to run E85 or any sort of flex/variable E content, just go P59 or standalone. IMO.
for LTFT/closed loop correction limit... E60 is about 20% more fuel than E10. E70 around 26%.
If it were my money I'd get very specific info on why folks don't like the P59. I can't fathom why a newer faster better PCM would be seen as inferior. Ask which tables lack resolution. I wonder if you didn't just misunderstand what the tuner told you?
Someone on this board explained it to me in depth, but it went over my head since I don't tune. There's a lot of discussion about it though if you Google search it (e.g., https://forum.hptuners.com/showthrea...-3-bar-OS-help)
It seems like people struggle to cram everything in and fine tune on the p59 a lot more than on a p01. Honestly, though, with this car's set-up, I wouldn't even trust a stock PCM to be making adjustments to open loop/PE. If the o2's can adjust for idle and cruising, I'm happy. I can run actual e85 (or close to it) at the track.
Here's the diff between P01 and P59 3 bar OS on hptuners. You get about double the table size on P01. P59 appears to keep the stock dimensions, so you lose some resolution. Are you actually going to fine tune each cell to that level of detail? Probably not, I suspect the P59 would work just fine, honestly.
I looked at EFILive COS for P59 and it is more like P01 on HPT-- you get 2x the VE table size. Another option.
One of the biggest downsides of stock PCM on such a setup vs a standalone is the lack of full time (dual) wideband control. I don't think the diff in VE table size is as significant as this shortcoming.
With that in mind, trusting the narrowbands and LTFT to correct WOT fueling with boost just sounds like a disaster to me. If you want to run E85 or any sort of flex/variable E content, just go P59 or standalone. IMO.
for LTFT/closed loop correction limit... E60 is about 20% more fuel than E10. E70 around 26%.
Thanks for the reply! This is just what I wanted to know. I also didn't know about EFI live COS. I'll look into that--sounds like it could be an option.
With that all said, I do plan to run full e85 or close to it at WOT (at the track) so it's really just a matter of getting the fuel right on the street in closed loop (where it will probably never see WOT or open loop outside of cold start idle). I'd never let the PCM to correct at WOT based on the narrow bands.
The video link posted in the link above is actually a good overview of all the things we're talking about. P01 vs P59 in HPT and what EFILive COS does.
Actually it seems like his biggest gripe is that the P59 3 bar COS on HPT, the VE table only goes down to 30 kPa (versus 15 kpa stock).... valid I guess, and never tried it myself.
The video link posted in the link above is actually a good overview of all the things we're talking about. P01 vs P59 in HPT and what EFILive COS does.
Actually it seems like his biggest gripe is that the P59 3 bar COS on HPT, the VE table only goes down to 30 kPa (versus 15 kpa stock).... valid I guess, and never tried it myself.
You're right, this video is awesome! Explained pretty much everything you discussed here with video of the actual tables and the EFI COS with stacked VE tables. I'm running 25 lbs of boost on 210lb injectors, so that p01 table looks a lot better to me. I don't plan to run true flex fuel (it'll never go below e60) or have the PCM adjust the PE tables based on fuel, so it seems like the p01 makes more sense in my case (and just relying on the o2's to make adjustments in closed loop when fuel is between e60-e84, since the VE tables will be set for e85). Realistically, down here in the south the e85 pumps don't go much below e70 (I guess maybe it could be e68 or something like that), and the % fuel difference between e70 and e85 isn't huge (I guess at WOT it'll maybe run 5% rich, so maybe a .1 off 1/4 mile time if I for some reason decided to run e70 at the track instead of running e85, which I dont plan on doing doing anyway).
Those stacked tables are what I have in my P01s and what I expected to see in a P59 with COS. I can't believe HPT crams 3 bar of fueling into 1 bar of space, that's hot garbage. In EFILive all the COS stuff goes in its own segment instead of being plopped into the tune as if it came there factory.
Those stacked tables are what I have in my P01s and what I expected to see in a P59 with COS. I can't believe HPT crams 3 bar of fueling into 1 bar of space, that's hot garbage. In EFILive all the COS stuff goes in its own segment instead of being plopped into the tune as if it came there factory.
Do the stacked tables actually work and goes the car really jump from table to table in real time while winding out the motor? In the video, the guy said he couldn't actually get his car to run with the stacked tables.
If you look at it and videos on the topic, the p01 VE table is a lot better. It basically just expands the table running twice or three times the resolution when moving from one bar to a two or three bar map.
My understanding is that HPtuners isn't to be blamed for what happens on the p59 (where it just crams 3 bars on a 1 bar map, making fine tuning impossible). The issue is that the PCM just doesn't have the space for a larger VE table, so I'm not sure how the stacked tables can actually work in the real world. Honestly, everything I read suggests the p01 is a much better computer besides the fact that you can run flex fuel on a 3 bar map the p59. Apparently, there's actually a OS where you can run flex fuel on the p01 on a 2 bar map (just not on a 3 bar map).
I'm going to stick with my p01 without flex fuel; that p59 table would run like **** with 210lb injectors and boost. I don't really want to mess with the p59 multiple VE tables nonsense (on top of that to run spark correction for flex fuel, you need to create a whole new table and try to get it to work). In my situation, it just doesn't make sense, I'll eventually go to a standalone instead. I'm good with the narrow band o2's making adjustments to the VE table when not in boost and in closed loop. Realistically, the worst E down here is going to be maybe e68, which is like 6% rich from E85 while in PE or boost enrichment, so not really a big deal.
This video is really good for going over the differences in the PCMs as well (it's a lot more detailed):
https://youtu.be/XC_W7S-grNw?si=nbJDuOjfyhydDHl8
03-13-2024, 07:40 AM
Closed loop and e85, no flex
