I just had replaced my my pipe from my cat to the muffler from 2" to 2 1/2" and put a muffler on with a 3" tip.Now im having a rough idle.The only thing ive done was a short ram intake.Theres no vacume leaks,the plugs are good and tomarrow im gonna check if its running rich or lean.Does anyone have any idea why this would happen all of a sudden?

 

o2 sensor? :dunno:

 

I had the same problem when I installed my Greddy Evo II. It turns out that the metal tab from the muffler that goes into the hangar was rubbing on the metal tab holding in the hangar. Check that out.

 

nope,nothings rubbing.I just changed the plugs and wires cause they needed to be changed anyway,but its still pretty rough.

 

Did you replace all gasgets?

 

no,it was just a straight pipe from the cat back.The guy who did it only clamped the piping to the cat.Should it be welded?It does have an exaust leak now.

 

Fix the exhaust leak and reset the computer. It should be bolted together with the apropriate gaskets or welded