sonny_k9

I have a 99 2.3 CL which is close to the 45k mark and is beautiful inside out :P
Though lately I've been feeling a lot more vibration, infact sometimes if I don't pull hard enough in 2nd and 3rd gear my exhaust rattles so much that I can hear a distinct/loud humm from the rear of my car. Even idling is not as smooth as it used to be.

What could it be? I've done regular oil changes and some break down mantainence so far nothing fancy. Could it be the tranny? I doubt beacuse the engine is out of sort even in neutral. The valves perhaps? A mechanic said I needed a $150 tune up and when I asked him whats included, he kept repeating spark plugs and air filter over 4 times....so I'm not sure. I would be happier if I could pinpoint the problem.

swclown

it could be as simple as the heat shroud on your cat - i had to rip that thing off likea year or two ago - it would rattle and hum at certain rpms and idle -sounded like a hole in my muffler sometimes
hope this helps

fusionnv

Minor Tune up these days are generally spark plugs, wires, and distributor cap, one or two other items i don't remember. I think major would include fuel filter and other minor items. I though it is a bad plug, because it would just be really out of wack. You can check them and make sure the gap is correct in case. Plus since u have the 2.3 it right on top and u can do yourself, extremely easily. On the v6, it a bit harder from the looks of it. I think plugs are out on the side of the engine from pictures. I never seen 3.0 engine in real life. It can be other stuff like mounts might be broken or worn out etc. I would get a second opinion from another mechanic. It sounds like the mechanic is just guessing.

chef chris

Sounds like a bad Cat I had a few years back...the inside had a chunk that worked it's way loose...would make the car shake like crazy...made a loud humming sound...got to the point it would shut the car off...

I'd check that out first...but a tune up isn't a bad idea if it's been a while.