connsean

I drive a 1997 LS 400 here in Phoenix. It has 216k, and has been running well since I bought it 6 months ago.

I recently got one of the catalytic converters replaced at a local muffler shop... only paid $290 taxes included. The car seemed to be running fine before hand, even though the check engine light would come on from time to time... but I left my latest emissions test too late, and the check engine light happened to come back on on right before I was going to get the emissions test done.

car passed emissions with no problems... but now, I'm a bit worried.

#1 The car is noticeably louder... (on ignition, it sounds as if I have a ricer exhaust system installed, or something) That I can handle

however, when I give it gas, it is extremely noisy now! If I get it up to speed, and maintain speed, it's pretty much as quiet as it used to be, but at the higher RPM's it's like a freaking motorcycle or something. Before I had the cat replaced... the car was always very, very quiet, like a LS 400 should be... now... it's only quiet when it's maintaining speed... but noisy when accelerating.

I've done some searches, and have read, any type of new after market exhaust parts can result in a louder car, but will eventually quiet down after you drive 400 miles or something...

Do I have anything to worry about here? I've read some horror stories of autoshops removing catalytic converters, instead of replacing them... but if that happened... I doubt I would have passed emissions testing ... could they have messed something up during the process of installing the cat? (I noticed they were using welding equipment during the process, but I think that's normal if they were installing an after market cat?)

#2 thing... is I find the car is getting decreased fuel economy... not a world of difference, but it seems to be burning quite a lot more gas.

Should I go back to the shop and get the guys opinion? Or should I drive it for another 300 miles or so, and see if it gets quieter?

Thanks for any help and advice! seems like a great forum community!

j2b4o

Guy messed up the weld and it's not air tight. Likely there is a very small hole or strip that either wasnt welded or didn't take it well. You probably have an exhaust leak. Take it back

PureDrifter

iTrader: (10)

sounds like an exhaust leak, but if you're worried give it a few hundred miles to bed in the cat and see if it's still as loud.

connsean

Thanks for the advice guys...

Not a car guy at all from a mechanical standpoint... But this sounds like the type of thing which could only get worse if it isnt re-welded to ensure an airtight flow?

Hopefully the repair shop doesn't give me too much push back. Seemed like a decent enough guy running the place though.

Again... Thanks.

akitomk3

iTrader: (2)

So did you get the CAT replaced as in replaced with an aftermarket cat or had the tech weld on a "cat" for you. It was really cheap replacing a cat in your case but then he could have done anything just to get rid of the CEL. Cause our cat can be taken out and replaced, not needed to weld something else in place.

Does it sound like a truck? Maybe an EGR leak? I recently had to replace my lower EGR tube on my 96 and yes it sounded like **** prior to replacing the tube. Sounded like a truck exhaust. You should bring it back to the tech and have him check up on why your car is noticeably louder than before. It shouldn't.

GQ420

That reminds me, my car sounds like a big *** truck. it seems like its running a straight pipe and when i start it sounds like a dam motorcycle.

RA010623

iTrader: (1)

the last owner replaced the two cat and i think the exhaust shop did a poor job there is leak at the cat flange to the hreader and also damaged the Y pipe there seem to be leak there.
my car also sounds very nasty right now

i'm trying to save up money to just replacement entire system with X pipe and magnaflow exhaust + resonator

NTRUDA

I had both my cats replaced back in 2009 even though one was bad and I had had all 4 o2 sensors replaced just to have that new feel for everything...I did get aftermaket cats also and the car has been quiet as normal and it's getting its normal gas milelage...more than likely you probably do have an exhaust leak. have then check that and also your o2's as well....good luck...

connsean

Thanks for the replies guys.

I brought it back this morning... (wasn't an exhaust leak)

the aftermarket cat he installed didn't have a resonator... (which is why it was so loud... he said it would have been louder, and I would have smelt it... if it was a leak)

So for $60, I got a resonator installed, and it's quiet as it was before... like it should be!


(i thought I replied like 8 hours ago... but guess I didn't hit "submit reply"


thanks again!

JradCelly

I'm glad you got everything sorted out , gotta hate having to take the car back to the repair shop :S

akitomk3

iTrader: (2)

That sounds really sketchy...I don't know what it means for a cat to not have a resonator. A cat is a cat, other than performing as a cat it should really be a resonator itself and not loud at all.