Up pipe down pipe???
30 May 2011, 06:42 PM
#1
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Up pipe down pipe???
I want to have my car remapped next month but want to do the normal upgrades first is it the up pipe that is de-catted or down pipe de-catted but I still need it to go through a mot which pipe???? Also I'm changing the air filter to a cosworth element but can I still run the car as normal with no problems I.e over fueling??? Before I do the remap cheers guys
30 May 2011, 07:57 PM
#4
Your car will pass an MOT with only a 100 cel sports cat in the downpipe.........provided it's heated up well beforhand.
For the WRX with the smaller TD04 turbo the ECU can handle fuelling / ignition OK without an immediate re-map. Spool might be a bit earlier and there will be more noise but you won't feel any diference in driving it as the power won't change (until the re-map).
The thing which I can't remember is if the MY05 had an up-pipe precat and EGT sensor like my bugeye.........I'll have a think or maybe someone else will post, my memory isn't what it used to be, well I was born in the 50's LOL
Shaun
For the WRX with the smaller TD04 turbo the ECU can handle fuelling / ignition OK without an immediate re-map. Spool might be a bit earlier and there will be more noise but you won't feel any diference in driving it as the power won't change (until the re-map).
The thing which I can't remember is if the MY05 had an up-pipe precat and EGT sensor like my bugeye.........I'll have a think or maybe someone else will post, my memory isn't what it used to be, well I was born in the 50's LOL
Shaun
30 May 2011, 08:13 PM
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I know on the later 2006-2007 hawkeye WRX and STI the uppipe is catless already. However I think on the 2005 blobeye WRX and STI has a small "pre-cat" in it. The uppipe if I'm correct, feeds into the turbo inlet and the turbo outlet connects to the downpipe and this is the section which contains the main big cat. This is the cat most people remove. You then have a "mid or centre" pipe which contains another smaller cat (often referred to as the "2nd" cat). So in total on your year car you have three cats - one in the up-pipe (pre-cat), downpipe (main cat) and mid-pipe (2nd smaller cat).
What you can do is fit a decat downpipe, so removing the first main cat, and keep the second smaller cat in the mid-pipe. And if you want to spend a bit more money even replace your up-pipe with a catless up-pipe. All of this would allow you to still pass the MOT, as the 2nd smaller cat is enough to allow you to pass emissions but yes you will need to drive carefully between having that done and the remap as you will run lean (ie under-fuelling) which is quite damaging, so keep the revs no more than 2k max to avoid this and will mean driving like a granny until you get the remap.
What you can do is fit a decat downpipe, so removing the first main cat, and keep the second smaller cat in the mid-pipe. And if you want to spend a bit more money even replace your up-pipe with a catless up-pipe. All of this would allow you to still pass the MOT, as the 2nd smaller cat is enough to allow you to pass emissions but yes you will need to drive carefully between having that done and the remap as you will run lean (ie under-fuelling) which is quite damaging, so keep the revs no more than 2k max to avoid this and will mean driving like a granny until you get the remap.
Last edited by matth76; 30 May 2011 at 08:15 PM.
30 May 2011, 08:17 PM
#7
Sorry.........I have to disagree. I'd completely de-cat and run a 100cel sports cat as a pretty foolproof way of passing MOT.
The DENSO ECU is pretty clever and unlikely to run lean as the TD04 will not boost spike. I'll have a look out for a well used diagram
http://www.wrxtuners.com/forums/atta...st-diagram.gif
Shaun
The DENSO ECU is pretty clever and unlikely to run lean as the TD04 will not boost spike. I'll have a look out for a well used diagram
http://www.wrxtuners.com/forums/atta...st-diagram.gif
Shaun
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30 May 2011, 09:52 PM
#9
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sometimes removing the pre-cat, down-pipe cat and leaving the 3rd cat can cause MOT issues as the 3rd cat can struggle to warm up/stay warm. Of course, as usual, this is probably theory.
I'm removing the pre-cat in the next few weeks as a lot of WRX owners in America have some harsh stories of cats breaking up after 30,000 miles & destroying the turbo. I think my WRX is PPP so the 3rd cat should already have been removed and replaced with a resonator? That will just leave the down-pipe cat which I'll eventually swap for a sports cat.
I'm removing the pre-cat in the next few weeks as a lot of WRX owners in America have some harsh stories of cats breaking up after 30,000 miles & destroying the turbo. I think my WRX is PPP so the 3rd cat should already have been removed and replaced with a resonator? That will just leave the down-pipe cat which I'll eventually swap for a sports cat.
31 May 2011, 12:05 AM
#10
I used to have a 2004 wrx (don't think the 05 is much different). The up pipe cat is extremely restrictive - get rid!! I got rid of the up pipe and centre section and got a H&S sport cat. Flew threw the MOT's no problem and fuel economy and turbo spool was massively improved (and power way up after a remap!) Best mod you can do on a WRX in my opinion.
31 May 2011, 12:11 AM
#11
I should add I got an ecutek remap and power went from 225 to 270bhp (with the panel filter and intercooler Y pipe - essentially PPP) The CEL is a simple fix, they just add a resistor if my memory serves me correctly. Hope this helps?
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