Question about VSS
03-10-2016, 09:20 AM
#1
Question about VSS I'm in the middle of an LS3 conversion (Camaro ecu and manual transmission) and am trying to decide about running a VSS or not. I may need it for cruise control with the electronic throttle, but there's an aftermarket solution that uses magnets on the driveshaft. For those of you not running a VSS with a manual tranny and electronic throttle - any drivability issues when those VSS functions are disabled? On the previous Ford V8 in the car, simply increasing the idle speed about 100-150 rpm did the trick. What's been your experience? Trying to resolve before I order my ecu/harness.
03-10-2016, 09:49 AM
#4
No tuning, just added the VSS, problem solved.
Dakota Digital makes a pass thru VSS for manual speedo output. It will signal the speed to the ecu to cure stalling issues, but does not provide a high enough pulse rate for smooth DBW cruise control.
For that, I added an aftermarket VSS to a T10 trans using the reverse gear as a reluctor.
http://www.dakotadigital.com/index.c...prod/prd57.htm
Dakota Digital makes a pass thru VSS for manual speedo output. It will signal the speed to the ecu to cure stalling issues, but does not provide a high enough pulse rate for smooth DBW cruise control.
For that, I added an aftermarket VSS to a T10 trans using the reverse gear as a reluctor.
http://www.dakotadigital.com/index.c...prod/prd57.htm
03-10-2016, 12:03 PM
#6
The Dakota Digital VSS puts out a very low pulse per mile. My stock ecu was reading about 5mph at 60mph. This still solved the stalling issue. I had it retuned to read correctly and still worked fine. The ecu can be tuned to accept over a wide range of pulse per mile values.
However the low pulse rate results in inconsistent speed readings so the DBW cruise control over reacts with nearly wide open throttle then directly to idle while trying to maintain speed.
However the low pulse rate results in inconsistent speed readings so the DBW cruise control over reacts with nearly wide open throttle then directly to idle while trying to maintain speed.
03-10-2016, 01:09 PM
#7
My plan has been to try and emulate the factory T56 set up by using the stock VSS sensor mounted OUTSIDE the tranny and reading teeth tacked to the yoke. 17 evenly spaced teeth just like the factory reluctor inside the tranny. However, someone I trust (in the tranny business) just told me the factory reluctor (inside the transmission) is magnetized steel....not sure what to do about that. Also not sure I can manage the air gap between sensor and teeth because the yoke moves a little bit.
Your comment about altering the ECU via tune to accept a different count VSS is interesting. Dakota makes an 4000-8000 pulse per mile cruise unit (designed to accept a magnet on the driveshaft) that works with the factory DBW set up. Wondering if I could also use that signal to provide the ECU what it wants. Sounds like your experience was positive on that front....
Which ECU are you using?
Your comment about altering the ECU via tune to accept a different count VSS is interesting. Dakota makes an 4000-8000 pulse per mile cruise unit (designed to accept a magnet on the driveshaft) that works with the factory DBW set up. Wondering if I could also use that signal to provide the ECU what it wants. Sounds like your experience was positive on that front....
Which ECU are you using?
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03-10-2016, 01:33 PM
#8
I'm running a 411 with the DD VSS, no cruise.
I've also got an 05 truck ecu I'm using with aftermarket VSS and cruise.
Jags that run sells a bolt on reluctor that fits the yoke of the diff and a standard GM reluctor that bolts to a diff mounted bracket (no movement). It's for an S10 IIRC, but would be easy to duplicate.
As for the VSS, any 2 wire (sine wave) VSS can work for the ecu. However, there's a minimum amplitude required. That will be determined by the VSS, distance to reluctor, and reluctor speed. On my 05, aftermarket VSS, a distance of 0.02" was required.
I've also got an 05 truck ecu I'm using with aftermarket VSS and cruise.
Jags that run sells a bolt on reluctor that fits the yoke of the diff and a standard GM reluctor that bolts to a diff mounted bracket (no movement). It's for an S10 IIRC, but would be easy to duplicate.
As for the VSS, any 2 wire (sine wave) VSS can work for the ecu. However, there's a minimum amplitude required. That will be determined by the VSS, distance to reluctor, and reluctor speed. On my 05, aftermarket VSS, a distance of 0.02" was required.
03-10-2016, 01:41 PM
#9
Appreciate your patience and responses Gary. I've got more homework to do.....don't understand this stuff well enough to move forward. And can't seem to get the same answer out of any 2 people.....convinced that most folks (not you, that's clear!) don't really know how they got theirs to work as they can't explain it. At least in terms that I can understand.
So, the pickup for my old Rostra cruise on the Ford V8 is a "2 wire" that senses a magnet on the driveshaft moving by the sensor. Is that generating a 'sine wave' output? I was under the impression that when the magnet is in the sensor and the iron-tooth is moving (as in the LS case) that it's generating a square wave output, not a sine wave output. Am I mistaken in that?
So, the pickup for my old Rostra cruise on the Ford V8 is a "2 wire" that senses a magnet on the driveshaft moving by the sensor. Is that generating a 'sine wave' output? I was under the impression that when the magnet is in the sensor and the iron-tooth is moving (as in the LS case) that it's generating a square wave output, not a sine wave output. Am I mistaken in that?
03-10-2016, 01:47 PM
#11
As far as I know all 2 wire generate a sine wave. The 3 wire generate a square wave.
The GM 2 wire uses a mag in the sensor and detects the metal reluctor going by. Check out the Jags That Run setup.
A 411 is the ecu used in 99-02 f body, corvettes, and trucks.
The GM 2 wire uses a mag in the sensor and detects the metal reluctor going by. Check out the Jags That Run setup.
A 411 is the ecu used in 99-02 f body, corvettes, and trucks.
03-10-2016, 02:46 PM
#13
TECH Senior Member
iTrader: (7)
The GMPP harness and ECU (E67) states that the VSS is optional. I use that harness and ECU with in my GTO and since I use a Richmond 6 speed I do not have a 2 wire VSS. I do experience an occasional stall when coming to a stop. It's fairly rare and usually happens after a prolonged period on the highway.
Andrew
Andrew
03-10-2016, 03:17 PM
#14
I had it down to a science where I could duplicate the stalling every time on both cars.
50 mph in 6th, press the clutch, and a long coast to a stop on off ramps.
50 mph in 6th, press the clutch, and a long coast to a stop on off ramps.
The GMPP harness and ECU (E67) states that the VSS is optional. I use that harness and ECU with in my GTO and since I use a Richmond 6 speed I do not have a 2 wire VSS. I do experience an occasional stall when coming to a stop. It's fairly rare and usually happens after a prolonged period on the highway.
Andrew
Andrew
03-10-2016, 03:53 PM
#15
Thanks guys - most of the harness/ecu shops I've spoken with indicate "....don't worry, optional." Clearly I don't think optional means what they think it means! Especially when you're trying to put together a package that's reasonably refined. Otherwise ----- carb. LOL!
03-10-2016, 07:12 PM
#16
I don't know if the Ford T5 for Fox & SN-95 ever had a VSS boss on the tailhousing that pointed straight at the mainshaft. The S-10 and F-body did. That, a VSS, and a reluctor would be a pretty easy fix to your problem. Or a boss could be tigged on. Gary's suggested VSS/reluctor gap is a little tighter than I have observed, but I don't doubt for a second that it works properly.
If you want subtle drivability issues, a high idle masking them, and no gains whatsoever, delete the VSS. The same vehicle with the VSS will drive better. It's been that way since the early 80s. Sure, it's easy to find fellowship in the "doesn't matter" club. But transitional changes in engine management parameters are helped by having a VSS.
If you want subtle drivability issues, a high idle masking them, and no gains whatsoever, delete the VSS. The same vehicle with the VSS will drive better. It's been that way since the early 80s. Sure, it's easy to find fellowship in the "doesn't matter" club. But transitional changes in engine management parameters are helped by having a VSS.
03-10-2016, 07:47 PM
#17
The T5 applications you mention had a plastic drive gear on the output shaft of the tranny that engaged with a plastic gear on the VSS sensor -- and then the speedo cable attaches to the back of the VSS. Pretty sure the boss/opening actually points either over or under the output shaft so that the gear on the sensor engages with the top or bottom of the drive gear; so I don't think it "pointed straight at the mainshaft". While anything can be made -- I think doing anything that involved trying to read a custom-made reluctor inside the tranny would be labor intensive and expensive. And I can't use the Ford VSS (with a circuit to modify output to be ECU-happy) because I don't have the room between the tranny and the tunnel in my application -- room for the cable to hook up to the tranny, but not for the VSS in between. That was the reason there was no VSS to start with. Drivability without the VSS was flawless on the 5.0L/T5 combo -- but I was only in year 19 of the beta test. 
Nevertheless, eliminating the VSS in this application is exactly the OPPOSITE of what I want to do Matthew. I'd like to come as close as possible to giving the ECU exactly the type of signal it gets in the factory application. It's simply that doing that outside of the tranny is proving to be challenging. For me anyway. But, perseverance will get me there. We're gonna try to rig up the yoke on a drill and use an oscilloscope and the factory sensor to see if what we've got will work. And then adjust accordingly.
Appreciate all the help guys.
Nevertheless, eliminating the VSS in this application is exactly the OPPOSITE of what I want to do Matthew. I'd like to come as close as possible to giving the ECU exactly the type of signal it gets in the factory application. It's simply that doing that outside of the tranny is proving to be challenging. For me anyway. But, perseverance will get me there. We're gonna try to rig up the yoke on a drill and use an oscilloscope and the factory sensor to see if what we've got will work. And then adjust accordingly.
Appreciate all the help guys.
03-11-2016, 07:34 AM
#18
You can always add a reluctor and VSS to a trans. I think Jags That Run has a bolt on as well as the diff mounted one.
I just added a VSS to my 10 using the 39 tooth reverse gear as a reluctor.
See post 25 in this thread. BTW, it was an aftermarket VSS, so that may explain the need for the narrow 0.020 gap.
https://ls1tech.com/forums/conversio...-ls-motor.html
I just added a VSS to my 10 using the 39 tooth reverse gear as a reluctor.
See post 25 in this thread. BTW, it was an aftermarket VSS, so that may explain the need for the narrow 0.020 gap.
https://ls1tech.com/forums/conversio...-ls-motor.html