I have a 1990 Buick Century that's been idling rough lately. It has the
3.3 V6 engine. The problem appears sporadically, and is most felt when cruising at around 45 mph, with no gas. At times the SES light comes on and stays on for a few seconds. The codes stored are 22 and 42. According to troublecodes.net: 22 - TPS voltage was under 0.24 volts for 4 seconds when ignition was on. 42 - The EST signal did not change when the ECM applied bypass voltage to the ignition module. Fuel pressure is where it should be. No apparent vacuum leaks. Spark plugs, wires and oxygen sensor were replaced less than a year ago. I'd appreciate a pointer in the right direction. On a car this old, I'd rather not use the trial-and-error method of replacing components until the problem is fixed ;) Thanks. Svilen- posted
18 years ago