What can you do if a new engine has an idle speed at 500rpm that's steady but not right?

Answer 1

Review the data for the vehicle online at a free information site, like the troubleshooting at autozone's site, or buy a manual for your model to get the correct idle speed. Normally, adjusting idle speed correctly requires setting the car to a diagnostic mode. This is often done by shorting specific connectors on a diagnostic connector, ensuring the vehicle is warmed up, the AC is off, it is in Park, and all accessories are turned off. In diagnostic mode, you should be able to set the timing (using a light normally) by rotating the distributor (for cars with distributors only). While you are in that mode, you can also check the idle speed, and adjust if your idle control system allows adjustment. Many vehicles do not allow or make no provision for adjustment. While timing can affect idle, the statement "I think you should advance the timing by adjusting the distributer a little until the RPM goes to where you need it" is not accurate. Set the timing to the specified value, then adjust idle speed. Advancing timing too far causes increased NOx emissions and stress or pinging, (and more power, to a point), reducing it too far causes loss of power and can burn valves. If your idle is still not stable after setting it to the specified value, begin troubleshooting per normal techniques.. like, checking EGR, for vacuum leaks, ignition issues, fuel delivery, etc.