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  1. #1
    Fuel Injected! KidTurbo's Avatar
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    GPS Speed Adapter for the most uncommon mods

    Here's one for those who like to swap modern EFI's into things that might not use a transmission, or way to feed the ECM a corrected Vehicle Speed Signal. In my case it was a boat, and I tested several of the latest GPS speedo converters out there. However the wave pattern was always wrong for my late model engine, so the ECM wouldn't recognize the pulse signal.

    Then I found this GPS-50 from Dakota Digital.

    Has a built the built in GPS antenna, plus an accelerometer that kicks in if sat signal is lost. I've used one for 2 years now, mounted under a 1" thick fiberglass dash. Amazing little box that will pump out about any wave type or resolution you'll every need. Just one wire to the ECM VSS signal, 12v hot, ground, match up the pulses per mile and your done.

    I don't work for them, or receive a dime from DD. Just like their stuff cause every time I've need some sort of special adapter, they say "we make that." And when ya like to DIY crazy builds like myself, it's cool to speak with someone who understands what your actually doing..

    That's my tip of the day.



    -K

  2. #2
    Super Moderator dave w's Avatar
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    I was recently thinking about a VSS solution for a marine application. I'm only in the idea phase for now. One idea that I have is to use the TPS output (0 ~ 5 VDC) as an input for a DC motor controller. I'm thinking the computer TPS circuit would not provide enough current for even the smallest of DC motors? The DC motor controller will speed up / slow down a small DC motor mechanically connected to spin a VSS. Hobby RC type motors and motor controller (with a dead band adjustment) are possible sources for my parts.

    dave w

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    RIP EagleMark's Avatar
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    Quote Originally Posted by KidTurbo View Post
    Here's one for those who like to swap modern EFI's into things that might not use a transmission, or way to feed the ECM a corrected Vehicle Speed Signal. In my case it was a boat, and I tested several of the latest GPS speedo converters out there. However the wave pattern was always wrong for my late model engine, so the ECM wouldn't recognize the pulse signal.

    Then I found this GPS-50 from Dakota Digital

    Has a built the built in GPS antenna, plus an accelerometer that kicks in if sat signal is lost. I've used one for 2 years now, mounted under a 1" thick fiberglass dash. Amazing little box that will pump out about any wave type or resolution you'll every need. Just one wire to the ECM VSS signal, 12v hot, ground, match up the pulses per mile and your done.

    I don't work for them, or receive a dime from DD. Just like their stuff cause every time I've need some sort of special adapter, they say "we make that." And when ya like to DIY crazy builds like myself, it's cool to speak with someone who understands what your actually doing..

    That's my tip of the day.



    -K
    I've looked at those before but the price scared me away from testing! Thanks for the tip! Perfect solution! Although still a little pricy, when building a custom system I don't think the cost is prohibitive!

    Dave W may have the cheap solution, especially when speed accuracy is not an issue.


    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  4. #4
    Fuel Injected! KidTurbo's Avatar
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    I tried building a couple DIY analog style setups before finding this little unit. First was a hall effect paddle wheel setup specifically made for boat nav/depth units. Looked good on paper, but once connected a sine vs square wave signal issues kept if from working. Wasn't looking to build a wave converter on top of the wiring job, so scrapped that one. Next was a pressure based rig, also didn't play out well.

    The biggest problem with any boat speedo is accuracy. Your standard old school marine speedo gauge units work off water pressure, or as above, a spinning wheel. Typically only accurate within 10-15% or so. New ones use a GPS to feed a dash speedo, but those wouldn't work with a ECM VSS either. The Dmax E60 ECM uses a high res 160k pulse per mile I believe, while some others GPS based units I testes were like 8 or 16k per mile. I could have adjusted the pulses with EFIlive, but once I found this piece and spoke to an engineer there who explained they built it to work with about any signal type ever used, I said ship me one and I'll let ya know. Within 20 minutes I had it wired in and ready to test.

    What's also nice is it has a calibration mode that puts out a 60mph pulse signal for testing. When I compared it to a handheld GPS, it was within 2mph out of the box. I quick calibration in EFIlive and that puppy is spot on at any speed. I've refered a few LS engine swap guys to this unit also, they said it worked fine in their swaps too. Checked my setting in EFI;

    {H0101} Vehicle Speed Sensor Pulses per Mile 127359.375000 Pulses/Mile
    {H0102} Vehicle Speed Sensor Pulses per Revolution 40.000000 Pulses/Rev

    $200 sounded pricy when I was doing this setup also, but after testing some cheaper ones, I can say it's worth every penny. Takes a thumping in the boat, high moisture local, and has done great. Battery drain was also a concern since it's always powered on. But it has a sleep mode built in and doesn't seem to have any noticeable drain when parked all winter...

    Best,

    -K
    Last edited by KidTurbo; 05-22-2014 at 08:55 PM. Reason: Added.

  5. #5
    Super Moderator dave w's Avatar
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    Quote Originally Posted by EagleMark View Post
    I've looked at those before but the price scared me away from testing! Thanks for the tip! Perfect solution! Although still a little pricy, when building a custom system I don't think the cost is prohibitive!

    Dave W may have the cheap solution, especially when speed accuracy is not an issue.

    The marine application I've been thinking about is using TBI PCM 16197427, which is 2000 PPM. The DD does support 2000 PPM. The TBI PCM does not need a VSS to be very accurate. The TBI PCM has near idle / off idle transition at about 3 MPH. I was thinking that the "plane" transition would be good place to switch from near idle / off idle fuel and spark tables.

    dave w

  6. #6
    Fuel Injected! KidTurbo's Avatar
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    That's kinda what got me on this project with the diesel. Needed the ECM to know when I was floating around "docking" or cruising down the river. Plus I have a couple J1939 CAN display units in the dash monitoring all the important pids, speed is up on there. Also allows ya calculate the MPG off the factory DIC settings. [Dmax averages about 5.5mpg in a 5000lb boat at 50mph]. And last, I'm thinking about adding some cruise control buttons to the steering wheel.


    The LS1 guys I spoke with also needed to control off idle fuel and timing tables. Guess those run pretty crappy without knowing your moving..

  7. #7
    RIP EagleMark's Avatar
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    Quote Originally Posted by KidTurbo View Post
    The LS1 guys I spoke with also needed to control off idle fuel and timing tables. Guess those run pretty crappy without knowing your moving..
    More then just the LS1 group! But without an E trans need for accuracy it's a lot easier to fudge moving and not moving.

    Nice find, thanks for sharing the results!

    Cost is really nothing when considering doing these high end swaps/conversions.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  8. #8
    LT1 specialist steveo's Avatar
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    that's a cool toy

    but my eyes, in a marine application, gps speed isn't really an appropriate input for something like a VSS, especially in the salt or rivers in diverse conditions.

    why? because of current.

    think about it. gps is speed over ground, pitot tube or paddlewheel is speed over water.

    example 1: you have a 5mph ocean current at your back. you're at dead idle in neutral. prop isn't moving. your 'gps vss' reads 5mph. a paddlewheel would read speed over water of ~0mph.

    example 2: you are fighting a hell of a storm, head on into current, and some big rollers. you have this thing FLOORED trying to get home. you are NOT winning this battle. gps speed varies between -10mph and +2mph, despite your boat working its ass off and speed over water exceeding 30mph.

    of course gps speed is the most useful metric for display speed in a boat since you equate it to travel time.

    in the same token, gps speed is the shits for a rolling vehicle because it doesn't compensate for angle of hills (gps speed up a steep hill is as the crow flies, not as the car drives)

    will it really matter? probably not, but on a boat i'd way rather have speed-over-water input for both datalogging and speed-related ecm parameters

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