easyrider

I've just decatted my MY01-up & down pipe,left centre cat on.

I've read that if you decat even just the downpipe,that the CEL light will come on because of "cat's below efficiency".

I went out for a 45 min blast around A/B roads last night,and didnt get even a flicker from the CEL.

Anyone know why???

BTW-its amasing the difference the decat makes.

easy

JIM THEO

You have one catalyst that helps a lot on this and also the ECU needs 3 consecutive failed emission drive cycle tests in order to throw a CEL PO420 code.
I believe (but not hope...) one day on open road/steady throttle or during warming up your car you'll see (unfortunately) the CEL!
JIM

chris singleton

I had a full decat on MY01 (up/down pipes, 2 piece centre and back box) and they forgot to fit the CEL fix (which I was unaware of at the time). The CEL didn't trigger for several months afterwards. I shat my pants when it eventually did thinking that it was something major (as I incorrectly thought that the CEL fix was in place).

It came on a couple of times after that (each time I was cruising on the motorway at 70/80).

As mentioned above I expect that it will come on eventually.

Chris

easyrider

Thanks for that fellas.

BretMan

I was curious about this too. I have an STI7 and fitted a Scoobysport downpipe over a year and a half ago.... I actually bought the CEL fix box but never fitted it.

I haven't seen a CEL in over 10,000 Kms and never fitted the box.

Must vary from car to car.

easyrider

Funny-mines a Scoobysport Up&Downpipe-im not sure if it helps,but ive lagged the pipes EXTREMELY well with 3/4 inch lagging used on boat engines(exhausts).

scub703

I suppose keeping the heat in the exhaust pipe would dicipate the unburt fuel and oil more efficiently. How much differance to performance was there after the pipes were replaced, i run a 2001

easyrider

It has totally transformed the car-more torque,the boost comes in alot stronger/quicker,revs easier throughout the rev range,and which i was quite suprised about was the fact that the peak boost seems to stay there right up to the redline in the lower gears-i havnt tried to see how it holds in the higher gears yet .It even pulls better in 4/5th gear off boost!!!
They say it adds 25-30 bhp decatting up/down pipes on the 01 cars due to the uppipe cat-but it honestly feels like its added 50-60 bhp.And even feels more like my prevoius M3 EVO.

Needless to say-im a very happy bloke at the mo

easy

hades

Cruise along at 70-80 mph steady for 20 minutes, and the light may well come on. Will never come on if you're just taking it for a blast, as the engine needs steady state to run the test.

If it does come on. just go for the resistor/capacitor fix - mine cost 22p and has worked for 7,000 miles without a glitch now.

P.S. get a TEK remap, that will solve CEL issues and make a lot more difference still to the grin factor.

easyrider

Update on the results on the partial decat

I lied about the peak boost holding to the redline-it does tail off slightly at high revs in the low gears,in 4th it holds peak(0.9bar) till just over 6k-then down to 0.7bar at about 6.5k

sapkan

I had mine WRX fitted with decat downpipe and decat twin center section from scoobysport yesterday, car is also running a Remus backbox. Have done bout 100 miles but no CEL light?!

I am coming to the UK soon so I was wondering whether to take the car's ECU with me and have a Ecutek remap done. Fitting the SS exhaust made a noticable difference to noise and go, is the Ecutek gonna help this any further?

are there any downsides to remapping?

Also did not get a decat uppipe as there are conflicting opinions as to whether the MY03 WRX actually has a cat in the uppipe. How essential is to upgrade the uppipe if it turns out that it has a cat?

JIM THEO

How is currently your noise compared with before, is so remarkable the difference with the down pipe-midle section combo?
The WRX03 unfortunately has a pre turbo cat thus is essential to change your up pipe, no huge gains except in turbo spool up.
I have no personal experience but only good is to have your car remaped with the free flowing exhaust!
JIM

Neil W

Decatted my MY01 WRX DP, Centre and Back. After 1 day CEL on! Next day fitted the fix.