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Thread: Commanded Fuel when Cranking

  1. #1
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    Default Commanded Fuel when Cranking

    Since the temps are getting colder my car isn't starting up as well now that it is running on e85. It seems as if it needs more fuel when cranking, so I have increased B3604 by about 20 percent. However it seems to make little to no difference. I'm confused on what this table is actually displaying? What are the values in this table?

    Mine goes from a vaule down at 1.2 at temps of -40 up to 25. But what are these values exactly? is it eq ratio? the description doesn't really say other than it is the commanded fuel. Is it grams/sec or volume of fuel? is it a/f ratio?????

    Also I'm thinking to help cold starts to increase the initial prime when the key is turned on?

  2. #2
    Joe (Moderator) joecar's Avatar
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    Can you post a pic of that table.

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    Click image for larger version. 

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    here is the table i'm talking about. Was hoping increasing it would help with my e85 cold starts.

  4. #4
    Joe (Moderator) joecar's Avatar
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    If you look at the upper right of the 3D view you will see that the units are AFR...

    ( the contents of that table don't look right )

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    If that is afr, how could it command those values? If i look at the stock tune they are very close and very similar values.

    What is the best table to add fuel during cold starts? I'm also going to go add some more timing as well when cold.

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    That table is very sensitive to adjustments and hard to pinpoint when it transitions to the OL commanded fuel table so tread carefully. I wouldn't do wholesale adjustments based on a %, but target a specific AFR value. If you look at a stock table you can see where the first couple of cranks per 90 degree (columns) are typically leaner, then richen upout for each crank after that. As Joecar mentions above, those values do look odd. You also have to consider the Afterstart Enrichment tables as well which are displayed in EQ ratio. Does the engine crank, but doesn't catch to hold a steady idle? If so, look at OL commanded table and Afterstart tables. Also note, E85 is not really E85 in Winter time because gas stations switch to a lower enthanol content for more gas to provide better cold weather starts, so you may have to actually lean it out. you can also use the DVT controls in the scan tool to play around with commanded AFR to see what the engine actually needs.

  7. #7
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    No the engine will crank and crank and crank and not fire up. So i will shut it off and turn it on and the second time it cranks a little while then finally fires up. Once it is running it is fine, but for some reason when it is cold it does not want to fire off right away. After it is started i noticed it is a little leaner than it should be, thus why I want to richen it up while cranking, then a bit more when ect are low.

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    Did you post the tune and a log showing the problem? I did not see one. Is this O/S 12212156?? What are you tuning? What are your mods? B3201 does not look close to what it should be, if I /we think you may be tuning, if we knew what you were tuning. What is B3202,3203,3204,3205,3623 set at. What does the wideband say? I dont understand how others can tell you what to adjust, when they arent sure what your running for mods or stock. Especially when you dont even list engine size? Whats wrong with 1.2 at -40 ? Is the table B3201 stock?? Can you post up your current tune for a more realistic approach at helping you fix your problem?
    1997 S10, 06 trailblazer SS LS2 swap, 4L70E trans, 76mm turbo. Factory ZQ8 suspension. 3.08, G80 w/a zexel. With a 0411 swap.

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    Here is my tune. it is a 2002 camaro and it has headers, full exhaust. There is also a cam installed in it, but I don't know the specs as it was there when i bought it. I put a racetronix wire harness and fuel pump in, then switched it over to e85. runs great the only issue is the cold starting. As the first try it seems like it will crank forever and not fire. Try it a second time and it will fire up.
    Attached Files Attached Files

  10. #10
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    BTW, i have changed the commanded fuel when cranking table. After realizing it is showing afr, but multiplying it by 20% this actually leaned out the table. So i put it to stock then increased the afr in the ranges i am having issues. Also i changed a lot of the starting tables back to stock that i had changed trying to help the starting issues. I will post new tune when i get a chance.

    Anyway after making these changes I tried it again. Does essentially the same thing. The car cranks and cranks the first time and never fires. Let off and hit it again and it fires immediately. I have no idea why it is doing this, and it is only when the engine is cold.... I'm not even power cycling the key, I simply let off from cranking wait one second then try again and it fires immediately... I'm wondering if it isn't a tune issue but something else?

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