mattyhfd

i have a 2009 2dr jk. i have an AEV snorkel and KN air filter. just put in a FLOWMASTER 40 SERIES muffler. since i put it in, after the jk warms up, i get a rattle sound (like marbles) when i accelerate. any ideas? could it be detonation? im gunna run my jk very low on gas and fill it with 90 OCT. and see if that fixes it. i need help. anyone else have this issue

ctra

New vehicles are made to run on a certain octane, if you have pinging higher octane probably won't fix it

JeepFish

First take it back to the shop that did the install and have them go over all their work (welds, hangers) and muffler itself. If that's not it take out the K&N , check the airbox and try switching back to stock filter.

mattyhfd

what would going back to a stock filter do?

cbrewer22

there is a piece in ur cats that i cant remember the name of but when it brakes it sounds like that. i have the same problem on my wifes ranger right now. if that is it u will need to replace the cat.

mattyhfd

it actually sounds like thats exactly where its coming from! how much does a cat cost? give or take

cbrewer22

i dont know man sorry. are ur rpms low and it sounds like it is going to die when u are at a stop in drive

andre1002

OP did you ever figure this noise out? My wifes JK is making exactly the same noise you described. Only when warmed up and only when accelerating.????
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