Jfsram

How does the computer know you are moving or not. Or is this just not required information on a 93.

I've never seen a sensor on these cars to let the computer know the speed but I found out something very interesting.

There is a long hill by my house that I can coast down in neutral. My truck loses a tiny bit of speed, my Park Ave actually gains speed and my Mustang maintains.

Why I ask the question is my Ram, which is all old school. Mechanical fuel pump, no computer with sensors etc. If I release the throttle to idle and/or coast. It will fall to idle speed. Exact same idle speed everytime. Not matter during coast or dead stop. It's a 5 speed, manual trans.
Both the Park Ave and an LHS I used to own. Hold the rpms up a bit during coasting in neutral. After the car stops, idle drops about 150rpms. So it's 1150 rpm during coasting and 1000rpm. Never thought much about it since these cars are so busy with sensor information, they often have alot of decision making going on.

My Mustang, does the exact same thing. During coast, it will hang the rpm about 950. Once I stop it will settle to 800. Why?

Joel5.0

1993 Mustang MAF systems do use a VSS to input vehicle speed information to the ECM.

mjr46

idle dash pot function causes such once speed falls under 3-5 mph idle should drop = normal