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  1. #1
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    JB3 fuel pressure / run lean protection

    Hey guys,

    Working on a few safety details in 2.0 to prepare for nitrous and one of the features I want to improve is low fuel pressure / run lean protection. And since the fuel pump is long cranking on our 135i I thought it make for an interesting test case.

    With the 4/4 alpha software we added fuel pressure as a logable parameter. Generally, higher is better. What I'm trying to determine now is where to default the safety cutoff. In the bad runs below AFR was a little leaner than I'd like but struggling to keep within range. Perhaps the best solution will be to make this feature fully user adjustable? Lets see some customer logs on known good pumps at various power levels for comparison.

    Here are examples of stock on a failing pump, which seems to more or less keep up given the low boost levels. Partial fail, and "getting worse". Also a customer "known good" log for reference. The map 7 and 9 logs are both on cars with meth kits supplementing fuel. The higher the number the more pressure is being delivered but it's not exactly linear. 20 is not twice as much fuel pressure as 10.

    Click here to enlarge
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  2. #2
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    Terry,

    So if we're running a JB3 2.0 with logging running maps 7 or 9, and we suspect a bad HPFP, would we be seeing what you've posted above?

  3. #3
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    You would see a fuel pressure plot that never reached target or one that slowly climbs to target, as he demonstrated above. Look at the black line. It should be full pressure when you are full throttle.

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    Click here to enlarge Originally Posted by SlicktopTTZ Click here to enlarge
    You would see a fuel pressure plot that never reached target or one that slowly climbs to target, as he demonstrated above. Look at the black line. It should be full pressure when you are full throttle.
    +1

    Actually I'd also like to encourage customers to post their own FP logs as well, so we can get a good feeling for the average at various power levels. Fuel pressure is a great indicator of overall fuel system health. Sort of like blood pressure is a good indicator of overall cardiovascular health.

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    Guess I'm trying to make sense of this but what will happen if using nitrous and the JB3 detects the fuel pressure is out of whack?

    Wouldn't the nitrous controller have to communicate with the JB3 to know to shut down or are you just cutting fuel?

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Guess I'm trying to make sense of this but what will happen if using nitrous and the JB3 detects the fuel pressure is out of whack?

    Wouldn't the nitrous controller have to communicate with the JB3 to know to shut down or are you just cutting fuel?
    The JB3 is the nitrous controller! Click here to enlarge

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    The JB3 is the nitrous controller! Click here to enlarge
    Ah, ok. Well, that is cool.

  8. #8
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    Added a user adjustable parameter for minimum fuel pressure allowable at WOT. But need some more customer logs for reference. Especially those with failing fuel pumps. Click here to enlarge
    Attached Images Attached Images  

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    Im happy to say, that my pump is not one the things currently failiing on my car, and Id like to keep it that way Click here to enlarge

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    Here is a log i did yesterday on my E90 LCI M 335i.
    1600 miles on here, had the JB3 on Map 7 for about 100-200 with a couple WOT, all else stock on 93 octane around sea level.
    New alpha firmware with some custom global settings
    Click here to enlarge

  11. #11
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    Are these #s in the Excel Spread Sheet? Are they under FUELp and what should those #s look like as I forgot to add fuel pressure in my latest logs chart?

  12. #12
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    Assuming you are using the latest alpha version they are under fuelP in the CSV.

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