I have an 89 RS TBI 305 with 54K on it. I have owned it for about 2 months now. I have noticed that at stop lights it idles at about 600 RPM's. Is this normal for this car?

The reason that I ask is that the Service Engine Soon light came on tonight driving it home. I don't know if it is that or possibly the fact that the temp gauge (sensor) isn't working (it works when it wants to).

Of course when I turned off the engine and turned it back on, the service engine soon light stayed off.

Everything else seems to be running fine. Any thoughts?

 

pull the codes on the car and let us know what those are and we can tell you more....

 

Assuming your tach is accurate, it's in the ballpark for a normal idle. If it's reading high like 90% of them are, then, no. Start by pulling the codes like NXS055 stated, and do the regular tune-up stuff. This is basically cleaning and re-gapping the plugs or replacing them altogether, cleaning or replacing the cap and rotor, checking the ignition module, coil, fuel pressure, O² sensor, relays, ignition timing, idle stop screw, and TPS voltage.

In case you don't know what "pulling the codes" entails, there is a writeup in the "tech articles" section on this website that describes how, as well as several cut and paste posts by Vader in the Tech and General Engine forum.

 

try adjusting the idle screw... see if it makes a difference