May have solved 100% E85 on LNF puzzle
I like to keep the LTFT's at +1.6 because the ECU tends to always want to pull fuel on the STFT's around -0.8 to -1.6. This keeps the sum very close to 0.0. If that's the case, the LTFT's will go to around -5 on E70, not a big problem either way IMO.
Update: New Intake Cam Actuator is in and after 10 miles seems AOK, I'll know more tomorrow.
Thanks for the input GMTech!
Got a new updated file to load tonight.
Last edited by Iam Broke; Mar 17, 2011 at 09:19 PM.
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No problem Tom, I'm glad that fixed it. Pretty common.
So we weren't going to go crazy on my son's Redline, but he realized there's an E85 station right near the university he's going to so guess what? He's on E47 too! KR at 3 degrees ign timing on premium gas is retarded, LITERALLY! He was actually hearing knock on the GM stage tune. Yikes.
I'm keeping an eye on this, the EFR turbo stuff and also some other interesting prospects for the LNF's turning up lately. I'm ready to go big turbo as soon as these guys get it figured out. Can't wait since I've pretty much done everything BUT the turbo, including the internal engine stuff. Better flow at high rpm's should make this motor a monster since I'm safe to 7500.
Keep up the good work!
So we weren't going to go crazy on my son's Redline, but he realized there's an E85 station right near the university he's going to so guess what? He's on E47 too! KR at 3 degrees ign timing on premium gas is retarded, LITERALLY! He was actually hearing knock on the GM stage tune. Yikes.
I'm keeping an eye on this, the EFR turbo stuff and also some other interesting prospects for the LNF's turning up lately. I'm ready to go big turbo as soon as these guys get it figured out. Can't wait since I've pretty much done everything BUT the turbo, including the internal engine stuff. Better flow at high rpm's should make this motor a monster since I'm safe to 7500.
Keep up the good work!
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No, it's a separate issue I've had for about a week. My intake cam actuator is popping an intermittent P0010 and stops responding after a while, sometimes the intake cam sits at 0.0*, sometimes it wanders around. The new cam actuator arrived today, hopefully it'll be resolved tonight.
Not whatsoever related to any ethanol . It just decided to die at 57k mi.
Not whatsoever related to any ethanol . It just decided to die at 57k mi.
Your car is a beast though. Mine is Sweet Melissa, she just wants to look sexy spinning tires at 70mph
Dude I'm about 90% sure that the mixes here in San Diego don't change at all any time of year.
Loaded latest updated file today, no long pulls but after a few short ones, still looking good!
I added another 8 gals of E85 yesterday, should be pretty close to full E85 now.
I added another 8 gals of E85 yesterday, should be pretty close to full E85 now.
Last edited by cubaniche; Mar 18, 2011 at 10:57 AM.
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From: Florida
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From: Florida
I was running up to 27* from 4k up and a lot more in the midrange than I am now until I vaporized #2 spark plug one day never showing any KR. All at once I logged misfires galore and most of #2 spark plug was gone. Detonation must've got me when I got cocky on the 60% E blend. :-/
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I am happy to report that we may have figured out (what should be) the last piece of the puzzle of running 100% E85 on the LNF. It's subject to further development and testing, but we seemed to have gotten past a major milestone.
I was actually reviewing a post on another lnf tech forum yesterday, from 2009 around the time when we sorted out the fuel rail pressure stuff. The post seemed to imply that the only way to increase fuel flow on the LNF was to raise the rail pressure because the injection window (amount of time we have to inject fuel on the LNF) was fixed. It also seemed to imply that the problem with injection window size was due to injection carrying over into the compression stroke and that going outside the injection window meant injecting fuel while the exhaust valve was still open causing soot build-up due to an improper combustion.
This implies that the ECM has a hard-set STOP injection point, and calculates the start of injection backwards from this point, meaning that any "time" that needs to be added goes onto the front of the injection pulse.
I don't believe this accurately describes what is happening, and maybe this has been debated here, already - if it has, I apologize for rehashing old discussions.
After some interesting discussions with the guys at ZZP who have more hands-on experience exercising the fuel supply limits of the LNF than I do, it started to sound like the problem wasn't the injection pulse starting too early, but rather it was ending too late - e.g. the injection is still happening when the ECM was trying to ignite the air-fuel charge! There is some math to explain this:
I've heard various numbers - some say injection window misfire sets in at "around 5.5ms" but I got some more detailed information from ZZP - they say that injection window misfire sets in at around 35% injector duty cycle, which is a more accurate way to describe the issue because it takes RPM into account. For example, at 7000 RPM, this would be 6ms.
We can use this figure of 35% IDC to estimate when the LNF starts its injection cycle. There are 720* of crankshaft rotation for all strokes, so 35% of this, or 720 * .35 = 252*. We also have to take into account ignition timing, which happens at, conservatively, 15* BTDC. So we add 15* to our 252*, and that puts the estimated start point of injection at around 267* BTDC.
It would seem this also dispels the theory that carrying over the injection into compression stroke is what causes injection window misfire. There is only 180* of crankshaft rotation from TDC (start of intake stroke) to BDC (start of compression stroke), but we can hit as much as 252* of injection window.
Our injection window size, could be, in theory, accounting for, say 20* of spark advance, 360 - 20 = 340* which would be 47% IDC, and 8ms (33% more fuel mass even at 7000 RPM!). The reality is, though, due to cam phasing events (e.g. exhaust valve still open - we don't want to spray fuel while the exhaust valve is still open), the window would likely be less than 340* maximum. But, then again, maybe we can get there - the LF1 engine (SIDI 3.0L V6) starts its injection almost that early.
With regard to running E85, raising the fuel rail pressure has helped us immensely, but that only shortens the required pulsewidth, it doesn't increase window size, and to run 100% E85 we need as much as 40% more fuel mass, and cranking the rail pressure up all the way doesn't *quite* get us there. I am Broke got somewhere around 67% E85 I believe with rail pressure at highest.
So, to summarize, by combining raised fuel rail pressure and changing the start of injection point on the LNF, we can increase the fuel flow potential, likely enough to run 100% E85 on the LNF. This is the part that we believe we've sorted out now. I'll be working on testing over the next few days, and a few people have offered to help test this out.
If it works out, we could be running 100% E85 in our LNFs within a matter of weeks.
I was actually reviewing a post on another lnf tech forum yesterday, from 2009 around the time when we sorted out the fuel rail pressure stuff. The post seemed to imply that the only way to increase fuel flow on the LNF was to raise the rail pressure because the injection window (amount of time we have to inject fuel on the LNF) was fixed. It also seemed to imply that the problem with injection window size was due to injection carrying over into the compression stroke and that going outside the injection window meant injecting fuel while the exhaust valve was still open causing soot build-up due to an improper combustion.
This implies that the ECM has a hard-set STOP injection point, and calculates the start of injection backwards from this point, meaning that any "time" that needs to be added goes onto the front of the injection pulse.
I don't believe this accurately describes what is happening, and maybe this has been debated here, already - if it has, I apologize for rehashing old discussions.
After some interesting discussions with the guys at ZZP who have more hands-on experience exercising the fuel supply limits of the LNF than I do, it started to sound like the problem wasn't the injection pulse starting too early, but rather it was ending too late - e.g. the injection is still happening when the ECM was trying to ignite the air-fuel charge! There is some math to explain this:
I've heard various numbers - some say injection window misfire sets in at "around 5.5ms" but I got some more detailed information from ZZP - they say that injection window misfire sets in at around 35% injector duty cycle, which is a more accurate way to describe the issue because it takes RPM into account. For example, at 7000 RPM, this would be 6ms.
We can use this figure of 35% IDC to estimate when the LNF starts its injection cycle. There are 720* of crankshaft rotation for all strokes, so 35% of this, or 720 * .35 = 252*. We also have to take into account ignition timing, which happens at, conservatively, 15* BTDC. So we add 15* to our 252*, and that puts the estimated start point of injection at around 267* BTDC.
It would seem this also dispels the theory that carrying over the injection into compression stroke is what causes injection window misfire. There is only 180* of crankshaft rotation from TDC (start of intake stroke) to BDC (start of compression stroke), but we can hit as much as 252* of injection window.
Our injection window size, could be, in theory, accounting for, say 20* of spark advance, 360 - 20 = 340* which would be 47% IDC, and 8ms (33% more fuel mass even at 7000 RPM!). The reality is, though, due to cam phasing events (e.g. exhaust valve still open - we don't want to spray fuel while the exhaust valve is still open), the window would likely be less than 340* maximum. But, then again, maybe we can get there - the LF1 engine (SIDI 3.0L V6) starts its injection almost that early.
With regard to running E85, raising the fuel rail pressure has helped us immensely, but that only shortens the required pulsewidth, it doesn't increase window size, and to run 100% E85 we need as much as 40% more fuel mass, and cranking the rail pressure up all the way doesn't *quite* get us there. I am Broke got somewhere around 67% E85 I believe with rail pressure at highest.
So, to summarize, by combining raised fuel rail pressure and changing the start of injection point on the LNF, we can increase the fuel flow potential, likely enough to run 100% E85 on the LNF. This is the part that we believe we've sorted out now. I'll be working on testing over the next few days, and a few people have offered to help test this out.
If it works out, we could be running 100% E85 in our LNFs within a matter of weeks.
Last edited by Terminator2; Mar 18, 2011 at 09:54 AM.
He lives! Welcome!! lol
Last edited by Iam Broke; Mar 18, 2011 at 10:32 AM. Reason: Automerged Doublepost
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So longer injection window=less needed fuel psi? I know that right now with larger turbo or doing the e-blend the underlay file has the PSI set to 2800 max. So, will it not be necessary to run it as high anymore?
Sorry for the newb question. Just trying to expand my grasp on what the changes mean.
Sorry for the newb question. Just trying to expand my grasp on what the changes mean.
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From: Florida
So longer injection window=less needed fuel psi? I know that right now with larger turbo or doing the e-blend the underlay file has the PSI set to 2800 max. So, will it not be necessary to run it as high anymore?
Sorry for the newb question. Just trying to expand my grasp on what the changes mean.
Sorry for the newb question. Just trying to expand my grasp on what the changes mean.
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Term, remember how I said I wanted to run E85 later on? There is a place near me who sells it... I'll need your skills for messing with the tune after Vince makes it available for 2010 bikes.
WhooHoo!
Sorry...couldn't help myself....
I got a chance to rip off 2-3-4 up to 120....er aah I mean on a closed airport runway...lol.
I attached the screenshot, ran very well but third is maxing out at almost 50% IDC, I couldn't get a good 60-100 time for comparison though as I was smoking second up top so bad I was over 70 mph getting into third, but no popping or other issues tonight at all.
The screenshot is of third & fourth, no intermittent P0087 logged at all. I wish I could log fuel pressure to see where it's headed. It's rockin' tonight!!!
More squiggly lines below.
Sorry...couldn't help myself....
I got a chance to rip off 2-3-4 up to 120....er aah I mean on a closed airport runway...lol.
I attached the screenshot, ran very well but third is maxing out at almost 50% IDC, I couldn't get a good 60-100 time for comparison though as I was smoking second up top so bad I was over 70 mph getting into third, but no popping or other issues tonight at all.
The screenshot is of third & fourth, no intermittent P0087 logged at all. I wish I could log fuel pressure to see where it's headed. It's rockin' tonight!!!
More squiggly lines below.
Last edited by Iam Broke; Mar 18, 2011 at 07:24 PM.
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Other E85 capable SIDI engines from GM are starting as early as about 340*. Not that it's a fair comparison because that is an SIDI 3.0L V6, no turbo, and almost certainly has different cam phasing profile, but I plan to look at injection timing on the LHU (Regal 2.0 turbo) which is basically the same engine.
EDIT: Just checked the LHU cal, it calls for up to 354* for injection start point at max air mass and RPM. If we assume GM didn't change the camshaft and cam phasing strategy on the LHU vs. the LNF, it's a reasonably safe assumption that 354* is possible on the LNF as well. This also means that GM "preprogrammed" the LHU's ECM to support turbo swaps readily, at least with regard to the injection timing.
Last edited by VinceTrifecta; Mar 18, 2011 at 08:04 PM.
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I wish I had something to give to you. Lol. The difference in tuning with E85 is you may pass MBT without knowing it. Usually, with gasoline you hit knock around MBT so it can be a useful guide to know when you're close. This might not happen with E85 due to its knock resistance.
I'm going to the dyno tomorrow to optimize the tune for E85. After that I will have something to give you.
I'm going to the dyno tomorrow to optimize the tune for E85. After that I will have something to give you.