E85 (3 gal) + E10 (7 gal)

Discussion in 'Generation 1 Prius Discussion' started by bwilson4web, Jan 24, 2013.

  1. bwilson4web

    bwilson4web i3 and Prime

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    I have long wondered, what is the maximum E percent that works. So tonight I knew I was down 10 gallons and filled up:
    • 3*.85 = 2.55 gal ethanol
    • 7*.10 = 0.70 gal ethanol
    • 3.25/10 = E32
    So far, no problems.

    Bob Wilson
     
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  2. john1701a

    john1701a Prius Guru

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    E20 was mandated in Minnesota for 2013 a number of years ago... so there have been lots of studies on the topic... especially since both source & energy will be local. I haven't heard how that will shake out. But it's easy to imagine E15 being rolled out here without much concern. After all, the state did the same things with E10 over a decade ago... facing very similar type of resistance. It worked out fine. None of the fears ever materialized.
     
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  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I think the main problem is that the 52 mpg average in Bob's signature block will take a hit with so much ethanol in the mix.
     
  4. engerysaver

    engerysaver Real Senior Member

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    In Texas, our gas over the years is not as good as it used to be. Even the color of the gas varies. I do not trust the BIG OIL SISTERS? They say 10 % or less ethanol!! I think it might be 12 or 13 % right now?:mad:
     
  5. bwilson4web

    bwilson4web i3 and Prime

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    I'm just curious as to what is the maximum ethanol ratio that still works in our NHW11. If anyone has done the experiment, please let me know.

    As for the economics:
    So I've saved $0.60 on this fill-up. We'll see if there are any problems and then I'll try:
    • 3 gal / (7+1.8 gal) -> E29
    • 4 gal / 6 gal -> E40
    • 5 gal / 5 gal -> E48
    • 6 gal / 4 gal -> E55
    • 7 gal / 3 gal -> E63
    • 8 gal / 2 gal -> E70
    • 9 gal / 1 gal -> E78
    My expectation is any problem will be found in maximum acceleration up a hill. This will drive the injectors to maximum duration and when the limit is reached, it should trigger an alarm. I'll read the code(s) and worse comes to worse, pull over to the side and power-on restart the car.

    The one known risk is when the injectors run out of duration. This will force the mixture to run lean with the car at maximum throttle and lead to a rapid increase in exhaust temperatures to the catalytic converter and exhaust valves. The higher ethanol octane should minimize the risk of knock. So I'll configure the Graham miniscanner to record:
    1. ICE rpm - with MG1 torque to calculate
    2. MG1 torque - engine power output
    3. mass flow - ordinary fuel consumption, will have to adjust for new ratio
    4. injector timing - with ICE rpm, another absolute fuel consumption metric
    5. O{2} sensor voltage (or MG1 rpm) - to see a sampling of Lamda feedback
    6. spark timing - higher net octane should allow greater advance
    There are multiple, MAPCO stations with E85 and E10 but no straight gas. For straight gas, there are three independent stations but only one that also sells E85, "Fuel City." So what I'll do is measure with various MAPCO ratios. Once I have the data, I'll use "Fuel City" at the maximum MAPCO ratio and follow-up with a straight gas tank.

    One mistake is I didn't include the ~1.8 gal of E10 (generic) still in the tank. In effect, I have E29 in the tank accounting for the residual gas.

    In past fuel tests I carried a 1 gal container of the next test gas and drove the car to fuel exhaustion. But I have E85 in my 1 gal can. So what I'll do is premix E40 in a second, spare can and drive to fuel exhaustion. I'll refill from that can, drive to the MAPCO, add the 1 gal E85 from the first spare can and 3 gal from the E85 pump with 6 gal from the E10 pump. I know it sounds confusing but the result is I'll go from E29 to E40, the next step.

    Bob Wilson
     
  6. ChapmanF

    ChapmanF Senior Member

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    Bob,

    Do you have any concerns about materials compatibility in the fuel system?

    I don't know anything, it's just something I remember seeing brought up in past coverage of E85.

    -Chap
     
  7. bwilson4web

    bwilson4web i3 and Prime

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    Not for the short duration of this test. Ethanol is fairly benign for an alcohol. Methanol is pretty wicked stuff and that would would or could be a problem. There is a slight risk of water issues but I don't see that as an immediate or even long-term threat to the bladder, injector or fuel pump. But that is why we run a 'test', to find out.

    I have an E85 conversion kit but I didn't want to put it in until I knew the boundary between Prius vs E?? ... I'm funny that way.

    If I can map out the boundary, folks won't have to buy an E85 kit but could simply mix at the pump. Should gasoline become 'short supply', knowing the E?? ratio gives folks a way to stretch the resource.

    Bob Wilson
     
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  8. ChapmanF

    ChapmanF Senior Member

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    Interesting ... what are the contents of such a kit?

    -Chap
     
  9. bwilson4web

    bwilson4web i3 and Prime

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    It is a microcontroller powered by the B+ side of the injectors. Fuel injectors have B+ on one side and then the ECU provides 'a path to ground' to activate them. One side is alway 'hot' from B+. So what the E85 controller does is add additional time with the ground-side 'ON'. Really a clever hack.

    My speculation is by incrementally increasing the E?? percentage, I will eventually find the limits of the Prius engine controller. Right now, E29 appears to be OK but I haven't climbed Brindley Mountain on a 'Standard Day.' It got up to 50F but I really want it between 60F and 75F to do a credible test. We'll wait for Saturday or Sunday. <grins>

    Bob Wilson
     
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  10. NinnJinn

    NinnJinn Member

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    Have you been able to make the climb yet?
     
  11. bwilson4web

    bwilson4web i3 and Prime

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    I did but posted the data in the ZVW30 thread:
    * * *
    Last night, I ran the Brindley Mountain climb test with the NHW11. I was planning to use the Graham miniscanner but forgot I need an adapter to connect the serial cable. So I switched to the AutoEnginuity and recorded what I could to generate this graph:
    [​IMG]
    First impressions:
    • Long term, fuel trim varies during drive operation - it looks more driven by the short-term variation and not something that might follow the fuel type in the tank. My new understanding is the long term is in effect the mixture setting. So the E29 (calculated) has resulted in nearly an 11% increase in the average pulse width at normal power range. During the maximum power event, the fuel trim has gone ~8%.
    • Fuel enrichment cooling - we know the 1.5L, NHW11 mitigates exhaust temperature by enriching the mixture and this is evident in the short term, fuel trim. Unexpected, the spark is retarded too.
    • Use of spark advance and long term fuel trim to find peak BSFC - unexpected, it looks like mapping the maximum spark advance may be a better way to find the peak, fuel efficiency rpm range in combination with long term, fuel trim.
    I need to replicate this data with the ZVW30 but my initial impression is long term, fuel trim may not follow the tank but follows the current drive cycle. I understand this is saved for the next start and may be the 'missing link' for the cold-start, 1.8L engine start knock.

    Bob Wilson
     
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  12. bwilson4web

    bwilson4web i3 and Prime

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    Every now and then, you find a new way to look at Prius OBD data that gives new insight:
    [​IMG]
    The thermodynamic efficiency of an internal combustion engine is a function of mixture and expansion ratio. So when I recently looked at my E29 test data from AutoEnguity, I realized these two critical metrics could be combined in a single graph (see above) to map:
    • Blue bounded area - a combination of high spark advance (i.e., maximum expansion ratio) and minimum mixture. My eyes say 2,100-2550 rpm is the best, power efficiency region for our 1.5L, NHW11 engine.
    • Green bounded area - sometimes you have to accelerate and this is the next best region. The mixture has gotten richer but the advanced ignition means you are getting a good return on investment.
    • Red bounded area - sometimes you just have to 'punch it' and the mixture goes rich and the spark has to be retarded to avoid knock (i.e., detonation.) My expectation is that higher octane ratings from more ethanol will move this boundary to the right ... allowing more power at higher rpm, the 'green' bounded area.'
    This is the first posting. PLEASE DO NOT PROJECT TO THE NHW20 NOR THE ZVW30. This is specific to the 2001-03 Prius. I will be doing a separate analysis of the ZVW30. Although I do not have the data (yet), I believe it is specific to the unique, E29 blend, that I am testing. I expect the boundary between the "green" and "red" to move left with less ethanol (and octane) and right with more ethanol (and octane.)

    So as I was driving around Monday morning to work and around, I tried keeping the ICE in the 2100-2500 range while monitoring advance. The first lay observation is my speed soon reached 65-67 mph on the flats which is a familiar 'knee in the curve.' In our NHW11s, MPG falls off rapidly above 70 mph.

    The second is running at this power level forces the car to stay in higher, drag energy regions. In reality, it is drag energy that determines how much power is needed. A more efficient engine is not going to reduce this energy tax. So I see these power regions as being more 'sort term' than sustained cruise operation:
    • 2100-2500 - urban acceleration traffic permitting
    • 2500-3500 - hill climb limits, traffic merge demands, traffic permitting
    • 3500-4500 - avoid if at all possible but sometimes you can't
    • 900-2100 - not to worry as these are low fuel consumption speeds anyway
    Thanks,
    Bob Wilson
     
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  13. bwilson4web

    bwilson4web i3 and Prime

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    Finally on E85 (or at least E70, MAPCO.) The car was down for a week while I got around to replacing the 12V battery. So I finally ran it dry on the Parkway this morning, 50 mph, headed North towards the Airport Road overpass.

    The trip meter showed 102.6 miles when the master alarm popped up. So I let the car slow to 40 mph and climbed the overpass to take the exit onto the access road. I merged with traffic and drove another quarter of a mile or so to the Lutheran Church parking lot that would be empty. There I added a gallon of what MAPCO calls E85 but labels a E70 minimum.

    When I started the car, the master alarm was still on but the miniscanner showed the engine running. So I drove down to the MAPCO station and filled up, 11.013 gallons. Given it was 2.6 miles and I'd just put in a gallon of their E85, I'm wondering if the bladder has gotten a little more flexible?

    When I turned the car back on, the master alarm was still on. So a second retry and the master alarm display went away. The miniscanner had two generic codes, one on the engine and the other the HV ECU. I reset them and drove into work, no problem including some Interstate high power settings, not maximum, just above 4,000 rpm.

    I've got to top off the tires and change the oil. Then I'll hookup the laptop and record some vehicle metrics . . . once the temperatures get above 60F. This will include a maximum power, hill climb to see if I can induce any error codes from the E85/E70.

    Bob Wilson
     
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  14. bwilson4web

    bwilson4web i3 and Prime

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    So after filling up with E85/E70(?):
    • 4 mile drive on the Interstate to work - fully warmed car, no problem, but not trying to hot dog it either
    • 5 mile drive to lunch, slightly cooled - again, the Interstate, it toss a "check engine" light about half a mile from the on ramp. Otherwise, car behaved normally. After parking at restaurant, read P0171 engine code and cleared it.
    • 5 mile drive to work, cooled during lunch - again Interstate with a 30m altitude gain and speeds to 70 mph, no problem and no codes.
    I also contacted MAPCO and the Alabama Clean Fuels Coalition to find out if there is someway to know what is actually being pumped. This way I don't have to carry an ethanol test kit and have to deal with the reactants later.

    Bob Wilson
     
  15. WE0H

    WE0H Senior Member

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    Hi Bob,

    Would you say the ICE was on cold start when it threw the lean burn code? My SUV only throws lean burn codes on cold start but never once the motor is warmed up and running straight E85.

    Mike

    Mobile on my SGH-i717
     
  16. bwilson4web

    bwilson4web i3 and Prime

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    It is too soon to say. On the commute home this evening, I got another 'check engine' but that was it.

    I'm going to have to do more tests with AutoEngenuity because it records the long-term trim. I suspect this is the critical metric. What I don't know is the limit.

    Bob Wilson
     
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  17. bwilson4web

    bwilson4web i3 and Prime

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    I'm waiting for the weekend to do a full set of tests with E85 but I had another P0171:
    • fully warmed, parked at Firestone to pay for a tire repair
    • started up and took a side street, within 1/4 mi, the "check engine" light came on
    • car continues to preform normally
    Bob Wilson
     
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  18. bwilson4web

    bwilson4web i3 and Prime

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    This morning, the car read 34F (1C), the coldest morning yet with E85. So I started it and began backing out when "master alarm" and "check engine" both came on and the engine stalled out. Hummmm.

    So I started the car and the engine ran rough at idle but pressing the accelerator, it smoothed out. So I went ahead and backed out and headed over to a breakfast business meeting with the alarms. On the way, I found and cleared:
    • P3191 - engine ECU
    • P3101 - HV ECU
    The Graham miniscanner doesn't read out the sub-codes so I can't tell what specific complaints were there. However, E85 has to be derated in the winter to 74% (E74) minimum ethanol in zone 2, Alabama, to deal with cold-start problems of ethanol. So I've just seen the ethanol cold-start problem.

    The engine sounded like it was missing on a cylinder but this could just be the problem of vaporization. But I didn't get any more problems by the time I reached the stop sign about 200 yards away. Even a little heat in the engine is enough to smooth it out.

    For a good read, "DOE/GO-102010-3073": http://www.afdc.energy.gov/pdfs/48162.pdf


    Bob Wilson
     
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  19. bwilson4web

    bwilson4web i3 and Prime

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    I am starting to see a pattern with the P0171:
    • park the car fully warmed up, normal hybrid mode
    • restart car within 1-2 hours while still warm (ICE 40C or warmer)
    • modest power, under 3,200 rpm, throws P0171 code
    I have yet to trigger it from higher power, 3,900 rpm or more, which makes some sense. This may be a region where automatic fuel enrichment occurs, not closed loop operation. Thus the long-term fuel trim never migrates to values that can trigger a P0171.

    I am surprised only one P0171 after a cold start out of at least a week. It is almost as if there is a temperature band during the warm-up with the exact power setting that can trigger the P0171. Hummm.

    Bob Wilson
     
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  20. bwilson4web

    bwilson4web i3 and Prime

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    I've finished with as much E85 and ethanol testing as I am going to do for now:

    1) E85 - runs in both the NHW11 and ZVW30 but will raise a harmless, "check engine" light, P0171 code. Clear the code and keep on driving.

    2) Cold-start fuel trim - the initial fuel trim when the car is started is for straight gas. So in freezing weather with the engine coolant is 3C or lower, the engine in both cars will 'stall out.' Clear the codes and restart until enough latent heat is in the cylinders to keep the engine running.

    3) Ethanol is not priced per energy content - it has about 75% of the energy of straight gas and I could see this even without a formal mph vs MPG test. This was evident in my commuting MPG, ~35MPG vs normal 50MPG with with these temperatures. If E10 gas were priced $4/gal, E85 should be pump-priced at $3/gal. Right now, E10 is ~$3.60/gal and E85 ~$3.40/gal., if energy priced, it should be ~$2.70/gal.

    4) E55 - based upon measured long-term fuel trim, it looks like E55 is about as high as we can go and avoid the "check engine" light. So if one could mix 50/50 of E10 and E85, it would work. But until the E85 is priced at 75% of E10, it makes no economic sense.

    I understand my injectors may be much cleaner. I have not inspected the fuel line filters but there is no evidence of clogging at this time.

    Bob Wilson