My question is , does anyone know what a speed sensor is, and what it does. I was told i need a new one for my 96 windstar because it is rounning rough when i come to a stop and on occasion will quit. can anyone help.

 

Who told you it was the speed sensor? Not saying they're wrong, but my Taurus had similar symptoms and I cleaned the MAF sensor and it cleared it up.

My 93 F-150 had similar symptoms and need a new Idle control valve, also known as an IAC.

Not to muddy the waters...

Erik

 

Isnt a speed sensor fo the speedo? I think it is, cuase i really dont know why speed would have any effect on how the engine really runs....how do older car that have cable drive speedos and no speed sensor run that have EFI.

 

Upon reflection, I'll bet they were thinking of the IAC.

Do some searches on this, I think there are posts on how to clean and/or replace the sucker.

 

A speed sensor, commonly known as a VSS for Vehicle Speed Sensor, electronically reports vehicle speed for vehicle functions such as:

*Electronic engine management system (EFI)
*Speedometer/odometer/tripmeter
*Automatic transmission shifting and T/C lockup
*Cruise control
*ABS
*Onboard trip computers (for example, gas mileage)

For your vehicle, the first steps to diagnose the problem are to perform a visual on the engine looking for obvious distress to vacuum lines/components as well as electrical connectors/wiring/components. The next step is to pull code(s) to try to identify a fault in a particular system that is used by the electronic engine management system. Often the code(s) will point to a particular sensor. Because not all sensors are cheap, diagnostics are used instead of speculation/guessing/gambling to minimize repair costs and expedite the correct resolution of a problem. I could speculate on several reasons for your driveablility issue, but given the type of problem a VSS would be near the bottom of the list. Do you have a CEL showing? Autozone will pull codes for free . They would like you to buy something right away; I'd hold off until you have an understanding of what the code(s) means and what it's implicatons, including any sensors, might be.