How do you make RPM adjustments on a 1990 Toyota Camry when the RPMs are jumping up and down while in idle?

Answer 1

Sounds like you need a diagnosis of the reason for the variations in rpms first. I would start with simple and low cost - change the O2 sensor, distributor rotor & cap, ignition wires and spark plugs and set the timing to factory specs (possibly a bad firing plug causing the rpm to vary. When checking the timing was it also changing or was it steady? Variations could indicate a worn distributor or distributor gear, bad timing belt or bad sensors. When did you last change the timing belt? Check fuel supply pressure for possible fuel pump problem. Test the alternator for constant output. A compression test to check cylinder and valve problems (are you using oil other than leaks?) would show if there ar emore major internal problems. Adjustment of the idle speed is simple with a screw located near the air intake hose on the manifold.