I have a 1997 Corolla with 150k miles.
I had my catalytic converter and flex pipe replaced this summer. Lately, my car has been idling rough. While stuck in some horrific stop and go traffic three weeks ago, it started to make noises as if it would stall out. It didn’t, but it still sometimes makes those noises.
The car seems fine on the highway. No loss of power. I did think that the hood felt too warm on a recent trip, but the temperature gauge in the car showed no issue.
The car hesitated when I tried to start it last week, but normally starts fine. It was the first cold day of the year.
I saw some white smoke come out of the tailpipe last week. It only happened once. Coolant and oil levels are fine. The spark plugs look good.
The fill pipe has been leaking gas for several months. It leaks if the tank is more than half full and it drips a bit of gas when I fill up. Two mechanics have not been able to find the leak and have told me not to replace it until it is a problem, given the age of my car.
I took it to a mechanic today (not the one who replaced the cat). He told me that the rough idling is due to the new flex pipe being shorter than what was originally there. He assured me that the car is fine to drive long distances and that there was nothing wrong with it. There’s no check engine light or anything on the dash to indicate a problem.
I should be relieved, but I’m not. I’ve lost confidence in my car. Can the stalling noises and rough idling be explained away by a changed exhaust system? Or are these signs of a problem about to happen?