hoskib

iTrader: (1)

obviously not expecting a psycic diagnosis over the net but i've just been reading about peoples exhausts poping and banging running full decats, i've had a full decat for over 2 years now and it's only banged when i hit the limiter in first once, should it do it more often? the cars a uk MY99,full decat,panel filter.
car runs ok,boosts ok etc. but the main concern is the fact it goes straight thru the emissions at MOT time,not a problem coz i don't have to pi55 around putting cats back on,but seeing the grief some people have with emissions i'm just a bit surprised with mine. it's tested at the same place,on quite new machine and i don't even have to pay him to pass the car
any thoughts out there?
cheers

LB4

I've never had much in the way of bangs either, fully decatted and TEK3d ... but recirc dump valve still, just the occasional soft pop when changing down, but even then the exhaust has to be very hot after a fast run plus changing down at quite high revs.
I don't think mine is running lean, i have an AFR and Knocklink and its been this way since mapped.
I think its stranger yours is passing the MOT without any cats though.

Gary

hoskib

iTrader: (1)

cheers gary, maybe the dump valve is whats holding our cars back?? dunno to much about these things,just what i've read!
as for the MOT thing i can't understand it either, cars running fine, want to get an afr on it to make sure,but it smells like it runs rich like scoobies do(i'm on my 2nd and i can't tell any difference)
i do get the car quite hot when i MOT it so maybe this helps.
has anyone actually tried to MOT their car without cats or are they just taking it as read that it will fail? like i say it's done a properly as i can do it,maybe emission testing machines differ very slightly from test centre to test centre?

Dark Blue Mark

There's no way it should pass with no cats Are you sure the centre is decatted too?

Even of it was running lean I dont think it would pass, as you still have loads of HC's as a result of the combustion.

Somethings a bit odd there.

Any techies know?

MB

hoskib

iTrader: (1)

yeah, magnex twin pipe down pipe, straight thru magnex centre section,magnex back box.
had 2 MOT's with the car like this, very clean burn reported each time.
guy who does a few jobs on the car guessing that maybe the ecu adjusts fuel mix to suit how clean the car is burning the fuel? unlike a common garden gti that will just dump a preset amount regardless? i know **** all about engines so any thoughts would be appreciated.
cheers