Vss-ecm-stalling

PeteB

GT40s Supporter
Got my Dakota Digital GPS unit. They've changed the design a bit, part number is now GPS-5-2.

With the GPS unit in the setting mode it outputs a 60mph signal. To test, I hooked up my android tablet to the OBD port via a PLX Devices Bluetooth dongle and used Dash Command to display the info from the ECU.

From the VSS plug on the GM wiring harness, I connected the purple/white wire to the GPS unit and the other wire to ground.

I first tried Speed output #1 which is the "standard speedometer" output. VSS speed read zero. So, I tried Speed output #2, "AC speedometer". Now I got a reading on the VSS speed. With the GPS unit set to 54000 pulses, the VSS reading from the ECU was 32mph, and with the pulses set to 128000, the VSS read 75mph. I think that's probably close enough for the ECU to be happy, so I'll leave it at 128000 and see how it works.
 
Pete

Eventually I too will have solve this. Thanks for posting it up so we can follow your lead. I'm going to have to find the VSS system for dummies book however. I stink with electronics....and me an old Air Force guy. :laugh:
 
Got my Dakota Digital GPS unit. They've changed the design a bit, part number is now GPS-5-2.

With the GPS unit in the setting mode it outputs a 60mph signal. To test, I hooked up my android tablet to the OBD port via a PLX Devices Bluetooth dongle and used Dash Command to display the info from the ECU.

From the VSS plug on the GM wiring harness, I connected the purple/white wire to the GPS unit and the other wire to ground.

I first tried Speed output #1 which is the "standard speedometer" output. VSS speed read zero. So, I tried Speed output #2, "AC speedometer". Now I got a reading on the VSS speed. With the GPS unit set to 54000 pulses, the VSS reading from the ECU was 32mph, and with the pulses set to 128000, the VSS read 75mph. I think that's probably close enough for the ECU to be happy, so I'll leave it at 128000 and see how it works.

I connected as per above, went for a spin and it solved my bucking issue. Thanks all... getting the VTR-64 safety inspection done on Wednesday.

cheers,

Craig
 

PeteB

GT40s Supporter
Good to hear it worked. I haven't gone for a drive yet.

I hooked the KOSO speedometer up to the GPS unit tonight. Took some trial and error with the settings on the KOSO, but I got it to read 61mph with the GPS unit in setting mode.
 
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Ok a stupid question......I suppose if the GPs network should ever go down or become less precise (the military has control, which probably means we have bigger issues), but is there a manual backup/primary capability that anyone has resolved vice the GPS solution...aka the number of pulses, sine curve etc that actually worked? Have not seen one.

Ex-military, so my search radar is up....Ha Ha
 

PeteB

GT40s Supporter
The KOSO gauge comes with a wheel speed sensor. It works OK, although I couldn't ever get it calibrated exactly right.

I wouldn't worry about GPS accuracy getting dialed down. Clinton made a presidential directive that the military wasn't to dial down the accuracy of C/A code. Bush and Obama have left that directive in place. Now the FAA is using GPS for air traffic control.

I did a tour in the Air Intelligence Agency which made me pretty paranoid, but I'm not worried about GPS.
 
Pete

I see your in Dayton, so your surrounded by paranoia up there...

Guess I'll spend some more money and get the GPS, system.....I'm so far ahead on birthdays and Christmas I will never live long enough. :laugh:
 

PeteB

GT40s Supporter
Took the SLC for a short drive, now that the snow has cleared. Stalling issue seems to be solved and the speedometer is working quite well with the GPS sender. :thumbsup:
 
Good to hear it worked. I haven't gone for a drive yet.

I hooked the KOSO speedometer up to the GPS unit tonight. Took some trial and error with the settings on the KOSO, but I got it to read 61mph with the GPS unit in setting mode.


Pete

Can you provide details on how you interfaced the GS-5 -2 to the KOSO with settings and wiring. I would like to do the same. Thanks
 

PeteB

GT40s Supporter
Pete

Can you provide details on how you interfaced the GS-5 -2 to the KOSO with settings and wiring. I would like to do the same. Thanks

I cut the cable to the KOSO speed sensor. It has three wires: red = power, black = ground, and white = signal. I taped up the black and red and connected the white wire to the Speed Output #1 on the DD GPS. With the GPS unit in setting mode, the KOSO read 225mph :stunned:. After some trial and error, I got it to read 61mph. Close enough. The settings I used on the KOSO were 25 sensor points and 310mm tire diameter.<!-- google_ad_section_end -->
 
I still don't understand why some of you are having this issue - I got my 917 driving on the road and this is the 4th GMPP harness/ECU i've used .... 0 issues with idle/stalling and my VSS is cut out of the harness.

My ECUs are all e67s with the ls3 525 crate engine tune, but different vintages (ranging from year 2010 to 2016), and not one of them exhibited any issues with stalling.
 
hah

I've had my fair share of GMPP wiring issues on this build, don't need more!

I accidently cut my original dbw harness and dbw is not one set of wires I'm willing to f*k with.

So I bought another harness only to find out that one side of the fuel injectors wouldn't fire

So I returned it and got another one, only to have it constantly through REP errors when I pushed the gas pedal and have it turn off my throttle body

So I returned it and got another one, only to find out this one would not turn off when the key was turned off

So I returned it and finally got one that worked!

Quality control, lol ..... and each time I had the entire car wired & loomed up and had to pull it all apart.
 
Alex, really hate to see the run of bad luck on harnesses.

The good news for the rest of us is we now know who has all the looming wiring experience to ask questions of........:laugh:
 

PeteB

GT40s Supporter
Well, I've got an appointment at Dyno Tune Motorsports (www.dynotunemotorsports.com) to do a custom tune and hopefully solve this stalling thing for good. If I had it to do over, I'd skip the Chevy computer and get an aftermarket setup that you can tune yourself.
 
Well, I've got an appointment at Dyno Tune Motorsports (www.dynotunemotorsports.com/]www.dynotunemotorsports.com.) If I had it to do over, I'd skip the Chevy computer and get an aftermarket setup that you can tune yourself.

Amen Brother, tell it all! At least then you know exactly what you have and how it is set up, and why it's set up the way it is...

I started looking at Motec to use with a Mercedes engine, and quickly realized that it would be a good choice for any engine. The downside is cost to purchase and program. But once you've set it up, it's pretty much bullet-proof.

I particularly liked the fact that you can tune it for turbos or supercharger, as well as for traction control that is tailored to your car and engine. Did I mention that it's pricey...?

Mike
 
Don't think an aftermarket setup is any better.

At one point i swapped my GMPP ecu for a Holley Dominator and had nothing but headache after headache so I went back to the GMPP ecu.

If you can't tune the GMPP ecu with HP Tuners I don't see how you'd have a hope in hell of setting up something more complex like a Motec.

Your stalling issue sucks but should likely be fixable by the tuner - I still don't understand how some of you have stalling issues given i've used 4 different GMPP ECUs across multiple years (2010 - 2016). The only thing I can think of is I'm using the LS3 525 one and maybe you guys with stalling issues are using the ls3 376/480 one? The 525 ECU package is like $50 more and I'm not sure why because all that should change is the tune, but hey, it's worked okay for me so I'm not questioning it.
 

PeteB

GT40s Supporter
I don't have HP tuners. That was my point - most of the aftermarket ECUs come with tuning software and a method to change things, either a laptop connection or a dedicated screen.

From what I've read, the 525 ECU has a much better tune than the 480 ECU. I don't know why the 525 tune is good and the 480 sucks, but it is what it is.
 
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