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Thread: GPS Speed Adapter for the most uncommon mods

  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!
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  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..

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    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!
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  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

  9. #9
    Fuel Injected! KidTurbo's Avatar
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    Quote Originally Posted by steveo View Post
    of course gps speed is the most useful metric for display speed in a boat since you equate it to travel time.
    I'm all about speed...



    Hauling butt, while also being about the "Greenest" thing out on the water has an added cool factor. If I could only find a totaled Tesla S for a good deal to play with, I'd step it up another notch.

    Your point is a good one Steveo. In something like a larger boat where your making 10-15 knots having a true speed over water would make more sense. As far as reliability, I've also use DD tach adapter for the analog dash gauge for 4yrs now. Both units are mounted under the dash, but not sealed and exposed to moisture. Last month I tested the salt water impact by running 25 miles in heavy off shore chop. Everything in the boat had a coating of salt when I made it to the trailer.. I would defiantly seal that unit up if was in more of a "fishing boat" environment.
    Last edited by KidTurbo; 05-23-2014 at 12:41 AM.

  10. #10
    RIP EagleMark's Avatar
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    Just a little bit more chop in the water and you'd have had blown past 80!

    It's amazing how 80 MPH on water feels like twice that on land. Nice work, not much noise either! I like it!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  11. #11
    Super Moderator Six_Shooter's Avatar
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    Quote Originally Posted by steveo View Post
    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
    This actually gave me more reason to not like these add-on GPS units for a typical conversion.

    In the Datsun S30 world people are swarming to GPS based speedos, because it's "difficult" to create a proper VSS signal, and then calibrating, oh man that takes "forever". :facepalm:

    My main problem with something like this is that any GPS unit I have used, personal navigation, smart phones, a couple laptop dongles all took a considerable amount of time to find satellites, even on clear days. There were days I would drive several miles before a good enough GPS signal was found. Now these were positioning based systems, but AFAIK the speed only based systems need the same 3 satellites minimum to provide an accurate speed. Even though I may not necessarily use my speedo as intended, I do like to know just what speed I am traveling at whenever the vehicle is moving. I can see overcast and story days being an issue as well. There are also areas where there are structures, like tunnels that could cause the signals to be lost.

    I have yet to have any real issue re-creating a proper VSS input for an ECM or cruise control in several swaps, mechanically. Yeah it may have taken a while to sort out the wheels and sensor location but I know it works, and it's in-expensive to assemble.

    Don't get me wrong, I do like the idea of a GPS speed sender, more as a back up, or being able to provide positioning data than just speed, but I just can't justify the prices I have seen and the known GPS issues I have experienced and read about other people experiencing. It's good to hear some positive reviews of something that works, for when the need arises.
    The man who says something is impossible, is usually interrupted by the man doing it.

  12. #12
    LT1 specialist steveo's Avatar
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    you know, a GPS speed with a level sensor so it could figure out the whole 'going up a hill' issue could be a bit more accurate on a road vehicle, but afaik you're talking some law breaking stuff here too

    a drivetrain driven speedo is legally required in every damn place i'm aware of; and pretty sure a functional odometer is too.

    also...... 'sorry officer, i didn't think i was speeding! my gps signal died when i went under that bridge, and the accelerometer must have been thrown off by those pot holes!'

    yeah right

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    RIP EagleMark's Avatar
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    I never took into consideration the GPS Satellite connection... yeah this is a major issue?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  14. #14
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by EagleMark View Post
    not much noise either! I like it!
    What?! Sounds like an F-14 on a fly by
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  15. #15
    Super Moderator dave w's Avatar
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    Quote Originally Posted by brian617 View Post
    What?! Sounds like an F-14 on a fly by
    Wow, you just dated yourself ... the F14's were retired form service in 2006.

    dave w

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