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Thread: Funny adventures in electrical engineering

  1. #81
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    yes, but the plane ticket would be pricey, and there's gotta be be bluetops around here that need the **** revved out of them... Nitin I'm looking at you.

    The good news is after testing it out I can move to a production type model, where I use a larger CPLD to absorb the functions of the two smaller chips and go surface mount on everything - the whole mod will fit inside the PCM case - and I can ship it wherever it needs to go cheap. Of course, then you'ld have to mod the ecu yourself which will require some special soldering skills.

  2. #82
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    Why not? Because these blue tops will let go like crazy over 8.

    Still cool.
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  3. #83
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    Quote Originally Posted by Warren View Post
    Why not? Because these blue tops will let go like crazy over 8.
    Good advice. 8000RPM sound like a good rev limit for a bluetop without bottom end work then? 9003 is basically just a number I pulled out of my rear to make an "over 9000" joke, which is almost as old as the internet itself (and I'm older than it still)

  4. #84
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    I rev my GZE to 8 all day. Looser limiter and all that. It has been reliable for the last 2 years of tracking. I would keep it there. For grip cars I would consider going higher, since it won't be sustained, but still yikes.
    BCWORKS

  5. #85
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    I believe that a 9k limiter is something that will work fine. It's like not having a limiter at all. Just be sure you don't bump up against it.

    IMO violently bumping the limiter at 8k and holding it there for a while is worse than revving it higher and shifting into the next gear.

    The blacktops rev to ~8300 and bluetops go to 7500. The tach obviously isn't accurate up at that range.
    - Brian


  6. #86
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    I have interest in this thread



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  7. #87
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    Quote Originally Posted by Brian View Post
    IMO violently bumping the limiter at 8k and holding it there for a while is worse than revving it higher and shifting into the next gear.
    My point exactly.
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  8. #88
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    Quote Originally Posted by Brian View Post
    IMO violently bumping the limiter at 8k and holding it there for a while is worse than revving it higher and shifting into the next gear.
    ...
    The tach obviously isn't accurate up at that range.
    You know, the old dodge k-car pcm I worked on implemented the rev limiter differently: it used a hysteresis effect where if the fuel cut was reached, It would not turn the fuel back on until the revs had fallen several hundred RPM. The effect was less entertaining (BAWPBAWPBAWP!) but probably far kinder to the bottom end - and it made it far more advantageous to shift gears because you were lacking power for a half second to a second depending on the vehicle dynamics.

    There is also the possibility of implementing a two stage limiter, where first timing is retarded to stupid slow levels - the engine just becomes a complete dog, then fuel is cut. again - easier on the bottom end because there's less shock loading/unloading.

    and I'm not sure what you mean about the tach there... are you implying that the driver wont be able to make a good judgement call as to how fast the engine is spinning? One thing I can say is that the crystal in the PCM is good to better than ?1000ppm, or 0.1%, or in this case 9 RPM



    Good science boys, keep it up!

  9. #89
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    Quote Originally Posted by Sparkie View Post
    and I'm not sure what you mean about the tach there... are you implying that the driver wont be able to make a good judgement call as to how fast the engine is spinning?
    Stock ae86 tach stops at 8k and most of the cars have an indicated 7800-8k rev limit when in reality its 7500rpm... But that's perhaps 5% optimistic, not bad for an 80s econobox.

    To take proper advantage of a higher rev limit, an alternate tach would be required.
    - Brian


  10. #90
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    Who's writing self modifying code in assembler at 4 in the morning? Boooyah it's me beechaz!

    This bootloader is gonna be sweet. Looks like I can do a prototype run of 6 boards instead of just three, reducing the PCB cost by a factor of two, all because of self modifying code in the bootloader.

  11. #91
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    So I'm back to source diving and I need some advice. From the look of it, the toyota code bounds the timing output from its algorithms to values between *drumroll*


    11 deg BTDC and 65 deg BTDC, and there seems to be an additional advance ramp that cannot be bypassed, which is past the limiter which can add up to 11.3 deg of additional advance at 7400 RPM.

    is it just me or didnt 65 deg already seem like a lot of advance, and then to have 76.3 deg of advance just seems off the wall. That would ONLY be at light load at 7400 RPM mind you. I need to hear from the more experienced bluetop guys that what I'm seeing it bonkers wrong, or within the realm of acceptibility for a tune that has to cover all possible operating conditions.

    and pretty pictures for all: here is the base timing 3d table (VAST beechaz!) from which timing is eventually determined, the contour lines into the picture represent load from 100% (foreground) 80%, 60%, 40%, 20% to 0% (background). matlab for the win once more.


    Last edited by Sparkie; 01-03-2014 at 12:06 PM. Reason: RPM scaling of image was incorrect

  12. #92
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    more interesting tidbits: TVIS is now deciphered:
    Code:
    loc_FC47:                               ; 
    ROM:FC47                 ldab    lilRPM          ; 24 = 600 rpm 255 = 6375 RPM
    ROM:FC49                 ldaa    Port1           ; interested in  bit 6 /TVIS
    ROM:FC4B                 anda    #$BF ; '+'      ; force bit 6 low, /TVIS on
    ROM:FC4D                 cmpb    #158            ; 3950 RPM
    ROM:FC4F                 bcs     setTVIS         ; branch if less than 3950 RPM to set TVIS ON
    ROM:FC51                 cmpb    #174            ; 4350 RPM
    ROM:FC53                 bcs     nosetTVIS       ; branch if less than 4350 RPM, no change to TVIS
    ROM:FC55                 ora     #$40 ; '@'      ; tvis off
    ROM:FC57
    ROM:FC57 setTVIS:                                ; 
    ROM:FC57                 staa    Port1           ; has capability to toggle bit 6 - /TVIS
    ROM:FC59
    ROM:FC59 nosetTVIS:                              ;
    TVIS is on below 3950 RPM, and Off above 4350 RPM, and between those values it is whatever it was prior. Hysteresis

    Additionally the timing calculations will add another 3 degrees of timing advance if TVIS is ON.
    Last edited by Sparkie; 01-03-2014 at 03:41 PM. Reason: timing calc just popped up

  13. #93
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    So at heavier load beyond 7400 it would not crank in crazy extra advance?
    1JZ 1984 Celica GTS
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    ? 1972 Celica race car

  14. #94
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    The timing looks about right. 94 octane and at 3-5 degrees does as pep for sure.
    BCWORKS

  15. #95
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    Quote Originally Posted by clay72 View Post
    So at heavier load beyond 7400 it would not crank in crazy extra advance?
    7200 actually, the final span is from 7200 to 8000, kind of a fail safe zone.

  16. #96
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    More data, this should be of interest to anyone running aftermarket management on their bluetop, or just bluetop injectors:
    The following table is the sum of deadtimes of the injector (opening delay-closing delay), or in other words, the total additive pulsewidth to get the precise volume of fuel you desire. The data in the table is interpolated from toyotas 7 element table, so that you can fill in the blanks with your own engine management, or just fap to it.

    Click image for larger version. 

Name:	injectordeadtime.JPG 
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    Voltage Deadtime
    7 2681
    8 2525
    9 22370
    10 2214
    11 2059
    12 1796
    13 1492
    14 1189
    15 988
    16 857
    17 727
    18 628
    19 567
    20 506

    Ignore the other attachment, that picture is wrong - it accounts for a voltage offset between chassis ground and the adc reference when none exists in a properly wired vehicle.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	injectordeadtime.JPG 
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    Last edited by Sparkie; 01-10-2014 at 04:23 PM. Reason: buggered up deadtime numbers because of a voltage offset. fixed now.

  17. #97
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  18. #98
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    visean is offline Yo, troubled night in the John
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    This is the info I want from a Blacktop ECU! Nevertheless, awesome job mate!

  19. #99
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    blacktop has some weird pinout micro, gonna take some real science to get that talking a language I speak, but rest assured it CAN be done.

    I'm getting dwell numbers along the lines of 6ms for 13v (normal-ish) + a static 11 Deg, unless that's too much, then a smaller term, but crap, 6ms is a lot to start with!

    Anyone got any factory bluetop dwell figures?

  20. #100
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    Figure out the injector dead times for 7mgte injectors. 400cc. It's what everyone uses for the boosts.
    BCWORKS

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