Hi I've a Import STI MY99 With a Apexi Exhaust and no other mods. I run the car on 99 RON all the time. I'm just wondering, my cat is blowing, which my garage has said it will be running lean now.

Can u guys tell me how serious this is as Im considering a Ninja Sports Cat from Scoobworld but can only get it now on 9mnths option. But if its ok to run it lean i can save up and get a replacement cat in next couple of months.

Cheers

 

Engine will fail if run on boost lean

 

I believe that it only runs a closed loop (lambda controlled) below 3000rpm, so I wouldnt lose any sleep.

 

Which cat is blowing, downpipe? Unless its the one in the up-pipe on a newage then the cat is downstream of the o2 sensor so it would make F all difference.

 

Any exhaust leak post 02 sensor won't have an effect, so on a 99 the sensor is in the top of the downpipe, any leak after that won't affect mixture at all.

Simon

 

Its the cat on the downpipe thats blowing. But its after the sensor. Its blowing from the actual cat.
So she will be ok Thank god as Now i can save up and not have to take a loan out now.