VSS necessity with EFI

[SevenT]

EFI Gurus,

Is the VSS signal absolutely necessary for the EFI to run?? Reason why I ask, is I have a Dakota Digital (DD) cluster and the output does not have a provision for VSS to the ECU. I tried to adapt the original VSS to the DD and it hits the shifter pill on the back of the transfer case. If someone has any suggestions, I am open to any and all. Thanks in advance.

v/r,

SevenT

 

[suckerpunched]

when I did my EFI a found different opinions, but what I am running is Early Mustang (91) OBD system and automatic transmission. I wired the VSS in but currently the connector is not plugged in to anything and it is running fine. I think it is possible that with a std transmission, when slowing down, the vehicles momentum will keep the idle at a higher speed than what the ecu wants it to be so it tries to lower the idle speed via the IAC. then when you step on the clutch, the engine slows down and since there is not enough idle air being let in, the engine stumbles or dies. That being said there are guys here that know a lot more about it than me and I will be interested to here what they say. Also I don't know about the requirements of OBDII or F.I. tech systems.

 

[SevenT]

Vss

Suckerpunched,

I am running an RJM harness that is OBD as well (86 to 93). I would not want it to die coming to a stop. Hopefully someone will chime in.

v/r,

SevenT

 

[904Bronco]

Take the retaining clip off the Ford vss, by spreading the tangs slightly, rotate it 180* and reinstall. Then squeeze the tips together so it stays in place.

Can you split the vss signal between the DD and the ECU? Or does DD say not to do that?

 

[SevenT]

Vss

904Bronco,

I clocked the Ford VSS the other way and it fits fine. It is the DD that has fitment issues with the shifter rails. I went back to my research on this and have seen how someone did some grinding on the DD to make it fit. I will attempt to replicate that and see what happens. Wish me luck.

v/r,

SevenT

 

[Broncobowsher]

I've heard of plenty running without the VSS. I would try that first. If you have issues, stalling when coming to a stop, then look at hooking it up.

 

[suckerpunched]

Suckerpunched,

I am running an RJM harness that is OBD as well (86 to 93). I would not want it to die coming to a stop. Hopefully someone will chime in.

v/r,

SevenT

I reworked an original harness, does the RJM have a VSS?

 

[CA Monkey]

i originally had my 89 mustang EFI system with ron francis harness (all the same pretty much) with the VSS hooked up to the rear axle which had it as it was out of a 94 f350. At some point on the Rubicon, the wire ripped off. I didn't notice the entire drive home and only realized it had come off when crawling under the truck.
I believe the issue that some have had was when using a computer from an automatic, you would come to a stop and the idle would hang on the high side for a couple of seconds. This is because the computer doesn't know that you came to a stop and its trying to keep the torque converter engaged like under normal driving scenarios. while making a harness I would leave a wire in that goes about 3 feet past your rear bumper, coil it up and wait to do anything else until after you drive it and see if there is an issue. Some guys like the hanging idle on the trail as it keeps them from stalling out

 

[Sledneck]

On one of my mustang conversions, I spliced the DD sensor signal to both the control box and the efi computer. That Bronco would like to stall when pulling up to a stop light after the clutch was engaged. Have no issues with the DD with both off one sensor. On my other mustang Bronco, I do not have the VSS installed, but have no issues.

 

[SevenT]

Vss

All,

I am running a stick computer. I will try to get the combo (Ford + DD VSS) to fit. If not, I will try just the DD VSS. Wish me luck...

v/r,

SevenT