So had the noise checked on my car today, and what was thought to be a lose exhaust guard turned out to be a rattly cat.

So what are my options (the car past it's MOT last week).

 

either new cat or a decat. I'd personally put a new cat on it, not worth the risk of running a decat. Pretty soon the cat brick will start breaking up and will block the exhaust.

 

O.K cheers Richie I've heard bad things about decats on a 170.

 

I had the same problem on mine a few weeks ago, check that there r 2 brackets holding ur cat in place as this causes the cat 2 rattle and eventually break. Apparently its a common fault on ST170's! If it passed its MOT then the emissions must b ok which would suggest the cat was / is still working.

 

I took my cat off my Focus and smashed the brick out the side of it, just put a bar down the engine end of it and give it a few whacks with the hammer and then shake the pieces out, made it sound a bit raspy but was only a cheap car.

 

That's an idea, I will take a look on the ramp on Monday, cheers.

 

Can you not decat it.Then do the mod to fool the ecu in thinking the cat is still there.

 

Thank Glen, I will take a look on Google

 

Decats are good until mot time where you will need a cat. Or if you get pulled over for a vosa roadside check, where you will need plenty of lube lol

 

Do you think the fact mine is rattly it would effect the overall performance of the car, as the flat spot around 2-3000rpm seems to be more apparent now, or is this due to the fact it's an ST170, and let's face it, they aren't really quick to begin with ?

Would a sports cat actually offer anything over a stock one other than noise ? or are there really any more gains to be found in a cat back system ?

 

The standard system on an st170 is actually pretty good, you might gain 2-3bhp from a sports cat but then again it'll be much more expensive than a standard one.

I would've thought if the cat brick is clogging the exhaust then you would notice a lack in power right through the rev range. You could always smash the brick out and see what happens. The EML will eventually come on though as the 2nd sensor will soon realise the cat isn't working as it should.

 

Cheers Richie, I will explore some options at work on Monday morning