What happens when I run too much ethanol?

Discussion in 'Generation 4 - General Discusson' started by b4black, Feb 11, 2019.

  1. b4black

    b4black Member

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    Car is stock for now. I sometimes run ~E30. I notice the LTFTs going up, but not that much.

    I was told not to run more than E30. What is the first sign of running out of fuel? The LTFTs or low fuel rail pressure, or AFR at WOT??

    Just wondering what to what to look out for.

    Thanks!
     
  2. 6500rpm

    6500rpm Quality Always Shoots Straight

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    I'd be guessing fuel trim should go up and possibly set a p0171 code. Not sure what effect it has on non FlexFuel fuel pump and related items long term.
     
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  3. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    I run between 30 and 40 percent. However, I have an E30 tune. You can run into low rail pressure, esp in colder climates.
     
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  4. b4black

    b4black Member

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    I'll be tuning this engine myself. I'm sure I can get the LTFTs back in line. Sounds like I should log fuel actual and desired rail pressure. (Maybe fuel pump duty cycle as well.) When the actual pressure can't keep up, it's time for more fuel pump.
     
  5. PaulTAutoX

    PaulTAutoX Member

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    Quoting title:
    What happens when I run too much ethanol?

    Well, I start weaving, and have to keep the driver's window down to stay awake.
    Reminds me of the proper use of nitrous: 2 way valve, either the engine or the passenger compartment is getting the benefit. :p
     
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  6. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    I like my nitrous, like my women....RICH and RETARDED.
     
  7. OmaHahn

    OmaHahn SHO Member

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    Well, my favorite gas station right by my house had 93 octane but they were bought buy Casey's General and they only have 91. How much do I mix e85 with 91 to get 93+?
     
  8. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    I got you.
     
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  9. Lostneye

    Lostneye SHO Member

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  10. b4black

    b4black Member

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    What would you be looking for on the log? I assume you mean fuel rail pressure.
     
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  11. Lostneye

    Lostneye SHO Member

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    I don't know enough to say everything you should be looking for but yes that would definitely be an indicator the car can't keep up with fuel demand. Either post it up or talk to your tuner directly.
     
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  12. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    Yes, usually 1500 psi the threashold people deem as completely safe.
     
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  13. b4black

    b4black Member

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    I just went back and looked at a scan I took after I first bought the car. Totally stock, at WOT, the desired fuel rail pressure was 2150 psi. and actual pressure peaked at 2500.

    fuel pressure.PNG
     
  14. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    That will change with load, more desired boost, ect..
     
  15. b4black

    b4black Member

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    Could you then explain why 1500 is a safe limit, but stock commands 2150? Are you trying to say with more load, more boost I somehow need to run less fuel pressure? Why does that happen?

    I figure at some point, the HPFP can't keep up with the demand and the actual pressure will be below the desired pressure. Then I risk not being able to maintain WOT AFR.
     
  16. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    What I am implying is whem you ask for more boost ect it will drop the fuel pressure. The difference in stock 11 go 12 psi is vastly different then 16 to 17 psi. You are asking for more fuel, more spark, and more air, hense why the fuel pressure at the rail drops.
     
  17. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    With that being said the overall consensus in the commnutiny is 1500 psi at the rail is deemed safe. Not ideal, but safe.
     
  18. Johnbigdog

    Johnbigdog SHO Member

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    I think the misunderstanding here is don't want to see fuel rail pressure drop below 1500 psi.
     
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  19. b4black

    b4black Member

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    Ah, got it. Thanks! Wow, that would be a big drop off from the desired pressure, but I guess the ECM can compensate since it knows the actual pressure and the actual AFR with a wideband. (In my other car, once the pressure dropped off at all, the ECM couldn't see it and therefore couldn't maintain proper AFR).

    I've been running up ~E30 and haven't seen the fuel pressure drop off. LTFTs get high, but no check engine lights. I'm just trying to get familiar with the engine management on the Ecoboost engines.
     
  20. Lostneye

    Lostneye SHO Member

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    The ECM will compensate stock and with most tuners. However with a tune especially in the cold weather you can reach the limit of the stock fuel system and as long as the tuner keeps the stock safeguards the ECU should proactively try and save the motor, some see hesitation, surging, missed shifts, as indicators of this but monitoring/logging would be the only way to know for sure.
     
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