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Thread: Commanded Fuel when Cranking

  1. #21
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    Doing the recommendations from 01z06 did help improve cold starting with e85. it isn't perfect but is better. I needed more time to get it perfect, but have torn the car apart to build a turbo kit.

    From what i have seen running on e85 it requires a lot of fuel when cold.

  2. #22
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    Quote Originally Posted by joecar View Post
    What is your B3601 set to...?
    10.09, commanded AFR part throttle is 9.76. Running OLSD in COS3.

    I've tried lowering cranking AFR with no effect. Put in the cranking VE table and commanded fuel on startup from a flex fuel tahoe with no difference.

    I cannot log AFR with my wideband on startup because the NGK AFX takes 20 seconds to read after starup

  3. #23
    Joe (Moderator) joecar's Avatar
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    I thought E85 had a stoich AFR closer to 9.6...

  4. #24
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    Quote Originally Posted by joecar View Post
    I thought E85 had a stoich AFR closer to 9.6...
    Stoich is 9.765 for true E85. But the stuff in the pump right now is winter blend, E70. So stoich is probably closer to 10.2. I don't see that making the difference here. 2 cranks tells me it needs more fuel dumped in, but I don't know how to get it in there in the tune.

  5. #25
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    Anyone?

  6. #26
    Joe (Moderator) joecar's Avatar
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    Post your tune file.

  7. #27
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    Cold start E85 tuning is hard to nail down. Have you tested the fuel to see what the actual ethanol content is? You would be surprised how much it varies. Something to consider is to increase the stoich to help compensate for the winter blend which has more gasoline and less ethanol. When I ran E85 I settled on 10.76 stoich for the "off months". It took a lot of incremental experimenting using the DVT controls to settle on this value. I'm not saying that value will work for your set up; but you should use that feature to help pin point the required fueling. Have you logged commanded AFR in the scan tool to confirm what the cold start AFR is? If it's richer than main commanded table; the adder/multiplier tables are probably adding fuel. Look at the Afterstart ECT Enrichment table which adds fuel on startup based on ECT. It's in EQ ratio (not lambda).

  8. #28
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    Quote Originally Posted by DrkPhx View Post
    Cold start E85 tuning is hard to nail down. Have you tested the fuel to see what the actual ethanol content is? You would be surprised how much it varies. Something to consider is to increase the stoich to help compensate for the winter blend which has more gasoline and less ethanol. When I ran E85 I settled on 10.76 stoich for the "off months". It took a lot of incremental experimenting using the DVT controls to settle on this value. I'm not saying that value will work for your set up; but you should use that feature to help pin point the required fueling. Have you logged commanded AFR in the scan tool to confirm what the cold start AFR is? If it's richer than main commanded table; the adder/multiplier tables are probably adding fuel. Look at the Afterstart ECT Enrichment table which adds fuel on startup based on ECT. It's in EQ ratio (not lambda).
    Cold start AFR is less than 6, that's all the gauge will read down to, maybe I can reconfigure it

    The only issue I have is cranking basically. Once the engine fires its smooth sailing. The blend right now has to be e70 minimum by law. But you are right, without testing I have no way of knowing the AFR. What I do know is that my ngk wideband reads 14.57 on the gauge when lambda = 1. And my AFR sits around that mark cruising and idling which means I'm near stoich. AFR and ethanol % is pretty irrelevant to me then.

    As far as cold start goes, it 2 cranks which would indicate more fuel is needed. Maybe I need to adjust that ECG table you mentioned. And it's also worth adding, cold temps aren't playing a role here down south. It's usually 65-70 degrees in my garage.

  9. #29
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    That's rich for E70. Adjust the Afterstart table in increments either way to see what the engine responds to. I would also try adding some timing on start up as well.

  10. #30
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    Solved the cold start issue...had to add a 0.2 oz initial fuel prime. Starts instantly like on gasoline. My only problem now is that anytime I turn the key on fuel is being squirted into the cylinder. If I don't start the engine I don't really want ethanol leaking down into my oil. I wonder if adding to the initial sequential fuel pulse would also solve the issue, without having fuel dumped with the key to the on position.

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