jon0886

iTrader: (1)

At idle, the engine shakes a bit, not too bad, but a bit more than what i would think is normal. At about 5500+ rpms, i can hear a lot of rattling. When I grab the engine and shake it, the engine mounts still seem to be good, but im not gonna rule it out.

What else could it be?

Right now im just gonna guess engine/tranny mounts, but i fear it could be worse.

RotaryEvolution

iTrader: (30)

is this 5500 RPMs while driving or in neutral? can you see where the rattling noise is coming from? if it is while driving then i would check your transmission mount and u-joints.

jon0886

iTrader: (1)

in driving, neutral, clutch in. the sound comes through the transimission tunnel. i can also feel it in the shifter. so probably the mounts? since its also in neutral, probably not the u-joint?

RotaryEvolution

iTrader: (30)

you could have 2 seperate issues, 1 being the engine either needs a tune up or has a sensor failed/failing causing the engine to run erratically. check for codes, you can do a search and come up with some results on how to do this.

the rattling could be any of a number of things, does the engine still vibrate when the rattling is occurring?

jon0886

iTrader: (1)

to the eye, the engine seems to be running smooth when the rattling is going on.
i'll go ahead and search up on checking for codes - my idiot lights could be busted - so i can't trust it even though it says theres nothing wrong. the seatbelt light keeps flickering and stuff.

RotaryEvolution

iTrader: (30)

i don't think S4 had a check engine light, mine doesn't, so you could have a problem and not know it until you check for codes.



one thing you may want to check also. turn the car off and let it cool down completely then take a rubber mallet or wrap your fist in a shop rag and pound on the bottom of both catalytic converters under the car, if they are causing the rattling then you should have to replace the one that is going bad, you won't know which is bad until you remove the whole pipe and see which side the chunks of core come out of, the cat could have just started coming loose also meaning that it isn't broken up but on its way out but will need to be replaced soon. a broken up catalytic converter can cause back pressure and cause the engine to run rough or lack power.

jon0886

iTrader: (1)

sounds good - thanks for the help!