VSS necessary while running speed density on a strip car?

3 Tone Fox · Mar 29, 2022

Ive heard lots of discussion on whether the VSS is necessary or not. I have an 87 GT with a TKX trans on a mega squirt2 ECU tuning off speed density. Its 80% going to be a strip car and 20% a street car, but I have no use for a speedometer or cruise control. I've already cut out a bunch of unnecessary wiring that the guy before me left in there, and now I'm down to the last couple things. Does the VSS or the amplifier serve a purpose for anything other than cruise control on an 87' gt with a manual trans given that I don't need a speedometer? Or can I cut it all out?

Mustang5L5 · Mar 29, 2022

On a 100% factory stock 86-88 speed density car, the VSS serves no purpose other than for cruise control. It wasn’t even installed on non-cruise vehicles those years.

With Megasquirt, you can get a speed signal out of it with a VR conditioner.

3 Tone Fox · Mar 29, 2022

Mustang5L5 said:
On a 100% factory stock 86-88 speed density car, the VSS serves no purpose other than for cruise control. It wasn’t even installed on non-cruise vehicles those years.

With Megasquirt, you can get a speed signal out of it with a VR conditioner.

So without having the pins on 3 or 6 from the speed sensor into the ECU, it wouldn't know its there? What is a VR conditioner exactly?

Mustang5L5 · Mar 29, 2022

3 Tone Fox said:
So without having the pins on 3 or 6 from the speed sensor into the ECU, it wouldn't know its there? What is a VR conditioner exactly?

Pin 3 and 6 are not present on a speed density ECU. That’s why when you convert a speed density car to mass air, you have to run the two wires from the VSS to the ECU and tie it into the mass air ECU on pin 3/6. There is no wiring connection from the VSS to the ECU on the speed density cars. It’s strictly 100% cruise control on those years. The cruise is 100% independent from the ECU. Delete away.

The Vr (variable Reluctor) conditioner is an add on to allow MS to read signals from a VR signal generator like a wheel speed sensor, some cam sync sensors and the VSS. It’s an add-on board that you need to wire in. Whether you can add it depends on your version of megasquirt. I am running an MS3X box I built myself so was easy to add this in to get speedometer readings.

Dual VR Conditioner Board V2.1

Your page description here ...

www.jbperf.com

3 Tone Fox · Mar 29, 2022

Mustang5L5 said:
Pin 3 and 6 are not present on a speed density ECU. That’s why when you convert a speed density car to mass air, you have to run the two wires from the VSS to the ECU and tie it into the mass air ECU on pin 3/6. There is no wiring connection from the VSS to the ECU on the speed density cars. It’s strictly 100% cruise control on those years. The cruise is 100% independent from the ECU. Delete away.

The Vr (variable Reluctor) conditioner is an add on to allow MS to read signals from a VR signal generator like a wheel speed sensor, some cam sync sensors and the VSS. It’s an add-on board that you need to wire in. Whether you can add it depends on your version of megasquirt. I am running an MS3X box I built myself so was easy to add this in to get speedometer readings.

Dual VR Conditioner Board V2.1

Your page description here ...

www.jbperf.com

I see I see. With that being said I'm going to cut all those extra wires out. You seem to be a fox body guru, which I'm extremely grateful for. Thank you

Willybill32 · Apr 2, 2022

Mustang5L5 said:
Pin 3 and 6 are not present on a speed density ECU. That’s why when you convert a speed density car to mass air, you have to run the two wires from the VSS to the ECU and tie it into the mass air ECU on pin 3/6. There is no wiring connection from the VSS to the ECU on the speed density cars. It’s strictly 100% cruise control on those years. The cruise is 100% independent from the ECU. Delete away.

The Vr (variable Reluctor) conditioner is an add on to allow MS to read signals from a VR signal generator like a wheel speed sensor, some cam sync sensors and the VSS. It’s an add-on board that you need to wire in. Whether you can add it depends on your version of megasquirt. I am running an MS3X box I built myself so was easy to add this in to get speedometer readings.

Dual VR Conditioner Board V2.1

Your page description here ...

www.jbperf.com

OK, Mike, a question: I converted my '86 to mass air back about 1995. I had instructions about wiring the VSS, but since I had no VSS I just ignored that step. I've never noticed a problem. Should I fix that?

Bill

Mustang5L5 · Apr 2, 2022

Willybill32 said:
OK, Mike, a question: I converted my '86 to mass air back about 1995. I had instructions about wiring the VSS, but since I had no VSS I just ignored that step. I've never noticed a problem. Should I fix that?

Bill

The biggest issue you’ll see not having the VSS hooked up is you might have the car stall out when coming to a stop, or you might notice a hanging idle when shifting to nuetral and coming to a stop.

If you aren’t experiencing that, I wouldn’t lose sleep over it.

96pushrod · Apr 2, 2022

The vss is completely unnecessary on a megasquirt equipped fox, I’ve tuned them without even having it plugged in at all without issue. The speedo is cable driven, so just leave that in so it works and you’re good.

Willybill32 · Apr 3, 2022

Mustang5L5 said:
The biggest issue you’ll see not having the VSS hooked up is you might have the car stall out when coming to a stop, or you might notice a hanging idle when shifting to nuetral and coming to a stop.

If you aren’t experiencing that, I wouldn’t lose sleep over it.

Thanks, Mike! I haven't had any stalling issues with the 'Stang since doing the MAF conversion. I had some teething pains after adding heads, cam, headers, etc. a couple of years ago, but once it was sorted out, no stalling.

Bill

VSS necessary while running speed density on a strip car?

3 Tone Fox

New Member

Mustang5L5

That is…until I whipped out my Bissell

3 Tone Fox

New Member

Mustang5L5

That is…until I whipped out my Bissell

Dual VR Conditioner Board V2.1

3 Tone Fox

New Member

Dual VR Conditioner Board V2.1

Willybill32

But at least it's tight!

Dual VR Conditioner Board V2.1

Mustang5L5

That is…until I whipped out my Bissell

96pushrod

I think they're a little easier to get off

Willybill32

But at least it's tight!

Similar threads

VSS necessary while running speed density on a strip car?

New Member

That is…until I whipped out my Bissell

New Member

That is…until I whipped out my Bissell

New Member

But at least it's tight!

That is…until I whipped out my Bissell

I think they're a little easier to get off

But at least it's tight!

Similar threads

Privacy & Transparency

Privacy & Transparency