Does anyone know if the vss (vehicle speed sensor) has any affect on the idel and, what exactly does it control besids the lock up converter?

 

Alot of ECM controlled items are referenced to the road speed
Fuel cut off when deccelerating ( DFCO ) for one; stops engine over reving as you slow down

 

That is a problem I having the engine is keeping a high idel as I pull to a stop and it seeming to be tied to my vehicle speed. Everything is factory eprom, ecm, but it just started after I ported my plenum maybe not related but, im guessing my vss is in my speedo my car is an 87 iroc tpi, and there is just a regular connection on the tranny. Can the vss fail or send a faulty message and cause this delay in bringing the idel down to 600 when pulling to a stop? Iv noticed it wont idel down till the speedo reaches 0 mph. As long as I keep moving at even 5 or 10 mph it keeps a high idel around 1000 to 1500. Can I replace the sensor in the speedo? or would this be an eprom problem?

 

The VSS is not "causing " the problem. If the ECM doesn't have the correct road speed input signal then it can't operate things correctly.
The VSS may have failed ; the drive gears may have stripped ( not uncommon ), could be a simple as a broken wire or connector.
Need to pull VSS out and inspect , check wiring back to ECM.

 

I know the speedo works so theres no broken gears but sometims if I dont drive the car often the speedo makes a loud noise and it shows a way higher speed than im going. Is the vss itself just that optical eye with a yellow housing that goes on the back of the speedo? My torque is acting funny too it locks up as soon as it hits 3rd gear. Im thinking theres something wrong in this circit somewhere, but it seems mor like a wrong signal insted of no signal at all. Like maybe it showing the pc that its always going 145 mph or something.