Weird noise at times

toyota
corolla

#1

my engine every now and then makes a lot of noise at startup for about 5 to 8 seconds at that same time the idle is very rough seems as if it is running on 2 or 3 cylinders instead of 4 after that it runs perfectly and is very quiet the car has almost 198000 miles on it


#2

Report the year.

Report everything about how well you keep up with maintenance - that doesn’t just mean how often you change the oil which is likely completely irrelevant to this issue.

Is this only at cold start? Only on a warm/hot start? Any old time?

I’m going to guess that the noise is just stuff vibrating from the engine running rough. However, if the noise sounds specifically like engine noise then you should have the exhaust system checked out.

As for the rough start up, I’d guess first at a fuel system issue - a bad check valve in the fuel pump that allows the fuel lines to lose pressure & empty out when the car sits, and then it takes the pump a while to get the pressure back up to specs. Someone with a fuel pressure gauge can tell you all about it.