Installing a VSS Sensor with Holley EFI

[Danny Cabral]

• This information applies to installing & programming a stand-alone VSS sensor with the Holley Avenger, HP & Dominator EFI.
To connect up to 4 Inputs & Outputs to the EFI main harness, use the Holley 558-400 I/O Auxiliary Harness.
If you're controlling an electronic transmission with a Dominator EFI, you must use that transmission's OEM VSS sensor.

If you have a cable driven speedometer, I highly suggest using an Auto Meter 5291/5292 Hall-Effect VSS sensor with your new Holley EFI.
The Auto Meter 5292 VSS requires a modification for use with a Fox Mustang speedometer cable end. Do not modify the speedometer cable.
The brass tube inside diameter must be drilled out to 17/32". Then measure the depth of the retaining rib on the speedometer cable's metal end cap.
Only drill down into the brass tube far enough to insert the retaining clip! However, I drilled a little further so I could add an o-ring for leak prevention.

The 16 pulses per revolution has excellent resolution for good signal at very slow speeds.
Also, it's a durable aluminum construction, as opposed to the plastic VSS sensor I previously used.
(I'm not using shielded wiring.) It works great on the Data Monitor, Datalogging and for Math Channels.
I find it very useful to know the vehicle speed (MPH), when reviewing a datalog for tuning purposes.
VDO also sells 5-28V Hall-Effect VSS sensors: LINK (#340013 FORD 90°), LINK (#340011 GM straight).

NOTES:
• When you setup the VSS parameters (I/O Digital Speed Input), there are a couple of caveats:
1) Start with the same number of "Pulses to Average" as "Pulses" (PPROT - pulses per rotation).
2) "Gear Ratio" - You must divide the rear axle gear ratio by the speedometer gear ratio (if you have a speedometer drive gear and a speedometer driven gear).
First divide the speedometer driven gear tooth count, by the speedometer drive gear tooth count, then divide the rear axle gear ratio by that number.
Unfortunately, this isn't in the Holley EFI instruction manual, so I'm informing you here.

Example VSS #1: A speedometer drive gear has 13 teeth, and the driven gear has 33 teeth (33 ÷ 13 = 2.54 speedometer gear ratio).
The rear axle gear ratio is 4.10, which becomes a final EFI "Gear Ratio" of 1.61 (4.10 ÷ 2.54 = 1.61 "Gear Ratio" in EFI software).
Example VSS #2: A speedometer drive gear has 8 teeth, and the driven gear has 21 teeth (21 ÷ 8 = 2.63 speedometer gear ratio).
The rear axle gear ratio is 3.31, which becomes a final EFI "Gear Ratio" of 1.26 (3.31 ÷ 2.63 = 1.26 "Gear Ratio" in EFI software).

Driveshaft Speed - This VSS sensor can also provide a Driveshaft Speed input by splitting the signal wire to a 2nd Digital Speed Input (RPM).
Example #1: Divide 16 sensor pulses per revolution, by 2.54 speedometer gear ratio, and enter 6.30 PPROT (16 ÷ 2.54 = 6.30 PPROT).
Example #2: Divide 16 sensor pulses per revolution, by 2.63 speedometer gear ratio, and enter 6.08 PPROT (16 ÷ 2.63 = 6.08 PPROT).
Currently, the PPROT parameter doesn't accept decimal values, however, it will in a future update.
Math Equation: Driveshaft RPM = 1056 ÷ (Tire Diameter x 3.1415 Pi) x MPH x Rear Gear Ratio
Example Holley EFI Math Channel, Driveshaft RPM: (1056/(25.6*3.14))*[VSS Sensor]*3.31
http://www.yellowbullet.com/forum/sh....php?t=1599178 (Driveshaft RPM to Miles Per Hour)
http://www.hurst-drivelines.com/?page_id=6025 (Wheel RPM & Driveshaft RPM Calculator)
http://www.advanced-ev.com/Calculato...ize/index.html (RPM/Driveshaft Calculator)
https://racingcalcs.com/menu-other/ (RacingCalcs Speed/Distance/Time Calculators)
https://forums.holley.com/showthread...5032#post75032 (Holley EFI Datalogger Math Channels)

• Some of the VSS parameters are "math operations" that occur on hardware vs the base firmware in the ECU.
They are performed when you key-on only. Meaning when you change it (click "Save"), it won’t recognize the change until you do a key-on event.
When you change some values with the key on, the math is incorrect because certain parts don’t get re-initialized, until the next key-on event.

• If the I/O menu icon (ICF) isn't already uploaded (added) to the top Toolbar, follow these instructions:
(This same procedure applies to all the various Individual Configuration menu icons/items.)
The "I/O" function is an "Individual Configuration" of the Holley EFI software.
At top of screen, Click "Toolbox" and "Add Individual Config".
At top of new window, select "Individual Configuration Library".
At bottom of new window, select "Holley EFI Inputs/Outputs Config".
Select "I/O" and open "Base Config - Blank.io".
The "I/O" icon will then be present at top of screen.
After creating the new Input, "Pin Map" it to an available ECU connector input pin.
http://forums.holley.com/showthread....8389#post58389 (How To Create A Custom Input/Output)

• To connect up to 4 Inputs & Outputs to the EFI Main Harness, use I/O Auxiliary Harness 558-400.
Eight Wire I/O Auxiliary Harness Connector Pin-Out (also in the Holley EFI Wiring Manual - LINK):
Pin A...A12...White/Blue (Input #1) F,5,2,T,H,G
Pin B...A3....White/Red (Input #2) F,5,2,T,H,G
Pin C...A13...White/Black (Input #3) F,5,G
Pin D...A4....White/Green (Input #4) F,5,G
Pin E...B12...Gray/Yellow (Output #1) H,P+
Pin F...B11...Gray/Red (Output #2) H,P+
Pin G...B10...Gray/Black (Output #3) G,P−
Pin H...B3....Gray/Green (Output #4) G,P−
http://documents.holley.com/199r10516.pdf (Holley 558-400 I/O Auxiliary Harness Instructions)
The 558-400 I/O Auxiliary Harness is 20 feet long, and it's "plug & play" into the EFI main harness.

[lnorton]

Can we input a VSS signal or a driveshaft speed with the HP ECU or do we have to upgrade to the Dominator ECU?

[Danny Cabral]

Can we input a VSS signal or a driveshaft speed with the HP ECU or do we have to upgrade to the Dominator ECU?

Yes, the HP & Dominator ECUs can be wired for a VSS or driveshaft speed sensor (LINK).
The HP ECU is only compatible with the better, Hall-Effect (digital) "F" Type speed sensors.
The Dominator ECU is compatible with Hall-Effect (digital) speed sensors, as well as VR Magnetic (inductive) "S" Type pickup speed sensors.
http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual - Section 9.1 "Inputs", Pages 27 & 28)
https://documents.holley.com/techlib...useanddiff.pdf (Holley HP & Dominator ECU Differences)

Hall-Effect: 3-wire, square wave signal (digital), pulse generation
VR Magnetic: 2-wire, sine wave signal (inductive), voltage generation
http://www.electronicproducts.com/El...g_for_you.aspx (Hall-Effect vs VR Magnetic)

[roytveit]

I have setup my Holley HP with the Auto Meter Hall-Effect sensor, as Danny describes.
I get my vehicle speed info when running a log, but I'm not able to get my Touchscreen to display the speed.
I guess I'm missing something here. How to setup the screen gauges? Thanks, Roy

[Danny Cabral]

I get my vehicle speed info when running a datalog, but I'm not able to get my touchscreen to display the speed. How to setup the screen gauges?

Currently, the 5.7" TSLCD can only display the numerical reading (TSLCD Data Monitor), not on a "Gauge".

http://www.holley.com/553-103.asp (Holley 5.7" Touchscreen LCD)
http://www.holley.com/data/Products/...R10524rev2.pdf (Holley 5.7" Touchscreen LCD Manual)

[Daniel6718]

Anyway to smooth that reading on the DS speed? I have one and it's very wavy, 4 PPROT the issue? I log at 20 FPS.

[Danny Cabral]

Anyway to smooth that reading on the DS speed? I have one and it's very wavy...

If the signal is choppy, especially at low speeds, try increasing the Pulses To Average.

...4 PPROT the issue?

Maybe, but first try increasing the Pulses To Average.

[Daniel6718]

Duh! OK will do. (It does it through the whole run, varies up and down 1.5 I think.)

[madramper]

What do you suggest if I use the Auto Meter GPS for my speed? It has an output of 16,000 pulses per mile. Is there a way to change it to PPM, or should I just do some math and figure out what ratio and tire size will give me the 16,000 PPM?

[Danny Cabral]

What do you suggest if I use the Auto Meter GPS for my speed?

I've never used the Auto Meter GPS unit.

Is there a way to change it to PPM...

No.

...or should I just do some math and figure out what ratio and tire size will give me the 16,000 ppm?

I'm not sure if skewing those (limited) parameters will render that result.

[madramper]

OK, let's see if this makes sense, or if I'm just rambling. :D
16,000 pulses per mile
5280 feet in a mile

It breaks down to 3.03030303 pulses per foot. To get the PPROT to be an whole number - 33 PPROT = 100 feet
A tire size of 38.2" gives you a circumference of 120" = 10'
A gear ratio of 10, times the circumference of 10', should give you that 100 foot total and the 33 PPROT.
Does that sound right or did I just over complicate things?
BTW, I would just go try it, but my truck isn't running just yet. I'm probably at least a month away from firing it up.

[raceoholic330]

Would a signal conditioner like the one below, get the job done to work with the HP? If it would, this seems like a nice way to get a speed input to the ECU, as well as another input to something like a traction control unit. http://jbperf.com/dual_VR/v2_1.html

[Danny Cabral]

Would a signal conditioner like the one below, get the job done to work with the HP?

Why do you need a signal conditioner? The HP ECU accepts a Hall-Effect signal directly from the sensor itself.
Does this device convert a VR sine wave signal to a square wave signal? Do you have an existing VSS sensor?

[raceoholic330]

I apologize, I did not specify the sensor I was planning on using. I would like to use my factory Ford VSS in my Tremec 5-speed, which has a sine wave output. The conditioner would make that a 0-5V square wave signal.

[Danny Cabral]

I would like to use my factory Ford VSS in my Tremec 5-speed, which has a sine wave output. The conditioner would make that a 0-5V square wave signal.

In that case, it should work fine.