wrxmania

Hi Greasemonkey (and anyone with else who may know).

In discussing removing the small cat nearest the backbox (and leaving the others - 2 more in my 2003 WRX) with my local Subaru dealer they said, as well as totally null and voiding my warranty it would certainly lead to Cylinder/Piston number 4 melting and being destroyed - seemed certain about it. Said "It's your car and you can do what you like but you either do this or you do it properly and fit the PPP".

Anyone got any comments on this - will removing 1 cat or more lead inevitably to this meltdown?

I might add I have all my cats and, for the sake of my warranty, will be sticking to my custom (not Prodrive) backbox only thanks!!

Thanks,

Brian

Adam M

its unlikely to cause your car to blow up.



on cruise and idle (closed loop running) the lambda sensors in the exhaust and maf sensors in the intake system control air fuel ratio in order to determine if you are running lean. When you remove a cat you improve breathing and which is the volumetric efficiency of the engine. When you do this, at a given rpm point, you need to add fuel to maintain the air correct air fuel ratio.

in closed loop mode this isnt a problem as the ecu compensates. when on boost you run open loop where the ecu looks up a reference chart (map) based on mass air flow, boost pressure, rpm and throttle position. This is a fixed map, and if your VE is increased to the point where the MAF sensor is already reading 100%, the ecu cannot add enough fuel to maintain a safe air fuel ratio.

you then run lean which can lead to melting pistons depending on how lean it is.

in this position you can remap the standard ecu via the ecutek route to make sure any improvement in VE is compensated for on the map.

if unsure of this then ring Pat who maps ecuteks and knows what he is talking about.

07803 906141


The third cat is not going to have an enormous effect on VE. People remove the other cats which

wrxmania

Thanks Adam,

Removing it voids my warranty anyway so I will be sticking with it for the moment.

Brian.

ozzy

ask them again (Dealer that is) next month Brian and you'll probably get a different response

If they're moaning about the warranty then there's not much you can do but to live with it.

Stefan

wrxmania

Thanks Stefan,

That was my reason for asking - warranty - pity they were not flexible - I doubt it has much benefit or detriment anyway. Can't be annoyed with the cats on, cats off scenario every service etc so sticking as is!!!

Nevermind, if I still have it in 2 years time, then I can do it then. Judging by the length most Scooby owners keep their cars - I won't

Brian.

ozzy

Well, I've had mine for 5 years now and it's still going strong. Don't take Chris (R-6) or John (EvoJKP) as normal Scooby owners those lads change cars more often than the Scottish weather

wrxmania

True Stefan,

There are oter doubters though, myself included, who have had weak times. Any tips for keeping it for a long time?

Brian.

julian N/W wrx my93

just took mine for the forth mot since it came in to this country, so i,ve had mine since july 2001!

wrxmania

Well done,

A stayer!!

RB5SCOTT

If you have a WRX as opposed to an STI i think you will find that you can play with the standard exhaust system a little more without running into trouble!

If you take all cats out and leave the induction system i think you will find that your car will be running no leaner than a 'safe' custom map, so taking one out will be ok for sure. As for the warranty issue, they only want you to spend £1600 on ppp Go to a different dealer with a more leaneant view

wrxmania

I would change dealer but they are genuinely very good and much better than any other dealer within 100+ miles - not too many options really.

Brian

wakeboardar

At the moment greasemonkey is working as a moving target at the skirmish paintball park

wrxmania

Thanks

ozzy

When it gets boring, mod it

I got bored with the handling, so I did some suspension tweaks.
Then got bored with the looks, so treated myself to some new alloys.

But the biggest reason for keeping it is that I don't want to spend loads of money constantly repaying a car. Mines bought and paid for, so it's less of a cost to run. Some people are just easily bored or haven't bought the right car.

Mines here to stay for a few years yet

Stefan

wrxmania

Good on you. More interested in brakes and handling. Prodrive springs just on. Some other bits soon. Brakes next I reckon.

The car is quick enough!

Brian

vulnax999

iTrader: (7)

It Passed ???!!!!??!!

wrxmania

Obviously did - good on you!!

wrxmania

Paintball over?

hugo

On a similar note (sorry to hijack but quite close to the original topic), if a person has a MY03 STi PPP and decides to change the backbox as well as the longer part of the centre section (the bit with the small resonator box immediately upstream from the backbox) would the slightly freer (?sp) flowing set-up upset the STi map? I'm sure all these changes are downstream from lamda sensor (which I think is in the proximal shorter part of the centre section). Please give me an ear-bashing if this is too much of a hijack wrxmania!

wrxmania

Hi Hugo,

This is the part I was planning on changing on my WRX, just also taking off the small cat (there are 3 on the WRX) also. I am still going to take away the resonator box but leave everything from the cats (and the lambda sensor) intact now.

Can't see that causing any problems personally with the WRX or the STI.

Brian.

hugo

I didn't think it would on the PPP exhaust setup as the third cat is gone already but you never know when you start monkeying around with flow dynamics! Lets hope GM appears and imparts some wisdom!!! Too late anyway as TSL group N backbox and deresonator distal centre section are winging their way towards Scotland!!!
H.

wrxmania

Where in Scotland are you Hugo and what dealer do you use (if any)?

Brian.

wrxmania

Any more comments?

ozzy

Brian,

They told me that a decat would melt #3 piston, so go figure. IM are taking a strong line on decats, so it doesn't leave the Dealers any option but to toe the line.

The PPP removes the cat, so that alone won't result in increased cyclinder temperatures unless the PPP ECU add's more fuel or does something else to reduce them. It's worth asking one of the ECU guru's if the PPP does any of that.

Stefan

ozzy

If you really want to mod it, then haggle for a discount on the PPP. I'm pretty sure there's plenty of margin for them to negotiate a discount (if they are willing).

You can get at least 10% with SIDC membership.

Stefan

The_Judge

Unlikely. The poor chap gets all upset when people start threads such as "FAO: Greasemonkey"...

hugo

Why?

p1doc

probably because he has a life hugo (only joking!)
your backbox etc is in safe hands but you do need a gasket!
martin