Does anyone know why you would get a thudding sound from your exhaust pipe. At idle the sound is similar to pouring oil out of the bottle, its a continuous thud thud thud thud sound or a low muffled pop pop pop pop sound coming from the exhaust.

 

I think I had the same problem you do... My reason was the fact that 3 injectors were stuck open shooting raw fuel down my cylinders- causing my engine to run rich, very rich. the thudding could possibly be unburnt fuel igniting periodically or every second or so, in the exhaust. do you have a cat? not having a cat will contribute to that noise if you're running rich... Just somethin' to check out


Stock exhaust? Engine size? Cat's? More info dude!

 

you could simply have a small backfire issue. check your timing and wires,plugs,dist. etc.