Exhaust Leak?
 

Hello guys, I have been having an issue with my 91 Olds 88 Royale for a couple weeks now. Its a somewhat load roaring kind of noise I am getting whenever I start to accelerate from a stop light etc... Its goes away after I hit 30 mph. I am thinking the muffler or catallitic converter is the cause because I had someone push on the gas pedal as I looked under the hood and around the car. I discovered that its definitely related to the exhaust system since I could hear it make a popping sound when it revved up. I recently had a tune up done including new plugs, wires, fuel filter, transmission fluid change along with having the O2 sensor and trottle position sensor, as well as a new starter. I did the paper clip test for any codes and it did show a 27 and 28, however no check engine light. It has 195000 miles on it now. I did have the muffler replaced about 5 or 6 years ago and it does have some rust along one of the edges and a tiny rusted out crack on the bottom about the size of a finger nail. So what are your thoughts on this????

The "doughnut" gasket between the ex manifold and ex pipe are famous for coming apart.........

Hear is an old trick.....pull out a plug in front...add just two drops of oil into the cylinder......get under the car and have someone start it......that will cause the exhaust to smoke briefly, and if there is an exhaust leak, you will see it....