Last Decat Question (Honest)

[chris_c201]

Alrighty Folks,

Got a decat down-pipe and a decat up-pipe sitting ready to be fitted....

As i'm looking to have a bash myself do i -

A - Attempt to fit both, planning on getting my headers ported in a couple of months then get a remap.

B - Fit my down-pipe myself just now and wait to get the up-pipe down when the headers are getting done (by someone else)

I'm happy to have a bash at fitting both but i'm nervous that i shear a bolt or something, is the gain from swapping the up-pipe worth doing just now or should i wait and get it done later?

Cheers

Chris

[Rice Rocket]

Chris,

Do the down pipe first, feel the diffeence and see how the cars responds to it, big differnce, wait a week or so and do the up pipe with new gasket, (biggish job) and then you'll feel an even bigger differnce in the cars performance!

Ricey

[TSL 333]

Alrighty Folks,

Got a decat down-pipe and a decat up-pipe sitting ready to be fitted....

As i'm looking to have a bash myself do i -

A - Attempt to fit both, planning on getting my headers ported in a couple of months then get a remap.

B - Fit my down-pipe myself just now and wait to get the up-pipe down when the headers are getting done (by someone else)

I'm happy to have a bash at fitting both but i'm nervous that i shear a bolt or something, is the gain from swapping the up-pipe worth doing just now or should i wait and get it done later?

Cheers

Chris

 

I bunged the guy at Macconichies to do it. When I returned to pick it up, the guy was cursing and swearing, his hands were all cut and it had taken him all morning!!! And he was a mechanic of sorts!!

 

Once all done, the difference is superb mate - even if just for the increased turbo spool up noise!!!

[Gumball]

Get them both put on and see how you feel after that.

Not much difference in labour when it comes to taking the up pipe off again for the headers to be modded.

[Rice Rocket]

Do it in parts, its so much better than all in one.

You'll enjoy the car more for doing it this way.

or just do the down pipe and get the headers and uppipe done when you have the headers ported.

Ricey

[G.Mac]

Do it all in one go, remember you have the cat in the up pipe, therefor removing the cats in the rest of the exhaust will make your exhaust gasses more free flowing and therefor more heat on you up pipe cat. You will then run the risk of your up pipe cat failing with the bits ending up in your turbo, wrecking it.

Remember once de catted you should be thinking of a remap to ensure that everything is running safely. Guarenteed once decatting you will end up with engine check light on.

(a tek 3 remap is 500+ vat)

After the remap with my car if felt smoother, more responsive and returned better fuel economy

Graeme

[Rice Rocket]

You don't need a remap after removing the cats, maybe on a STi you do.

[fai17]

You don't need a remap after removing the cats, maybe on a STi you do.

If you want to get the best performance with the parts fitted so a remap is certainly required.

Your CEL will come on and car may not run after that.

[G.Mac]

Yes your car will run, CEL light will come on, performance will be reduced as your ECU will over compensate and prob run megga ritch, does not matter wheather STi or WRX remap is the safest way to go!

(thats why PPP also comes with a remapped ecu after changing cats etc)

 

Graeme

[Rice Rocket]

We all know a remap will give you better performance with these mods.

The CEL light will come on but it won't stop the car running!

Are you not doing the CEL fix too chris?

[G.Mac]

Yes Chris is wanting performance, not just to run.

I cant imagine anyone running with a warning light on all the time, seems ludicrous to me as you never know what that light is for and wouldnt have any indication of a new fault if the light was already on.

 

Graeme

[Gumball]

you think the CEL comes on for no reason? It comes on to tell you that something isnt working right with the ECU/Car

So lest for instance say that your car has exhaust changes or power mods added to it and you dont get an ECU remap. What will happen is the check engine light will come on to warn you that there is a problem detected.

Do..............realise that when the CEL appears the ECU will retard itself to a certain extent to compensate or safeguard being the better word and ensure the thing doesnt break.

Yes, people do run about with decats, up pipes, down pipes, new turbos and get away with it for years. They are lucky in some respects cos their car isnt breaking, but unlucky on the other cos they never unleash the power benefits and safe running of their pride and joy by saving a few pounds.

Go get CEL fix and put the light out. Take the strereo out as well so you can hear the pistons slapping off the underside of the bonnet, the rods popping out or the big end going.

I have a car that has been mapped from teh day it was around 300bhp until now which is stretching out towards 450bhp and know the other people that have powerful cars and they are ALL SAFE

I also knew a guy that did crazy things and mods without safety and it cost him a brand new 54plate WRX. I had to sell the car after that.

 

 

[ANDYJDMSTI]

I also knew a guy that did crazy things and mods without safety and it cost him a brand new 54plate WRX. I had to sell the car after that.

 

 

FPMSL  []

I know my car is a different kettle of fish as it is a JDM STI with the twin scroll but when i got de-catted and was awaiting Uncle Forrest to map it i noticed the i was getting boost spike (overboost).

Although i did not get a CEL but i did drive it off boost 99% of the time til it was mapped and SAFE.

choice is yours but i know what i would do.........Again!!

 

 

[chris_c201]

Geez, this has kicked off!

I fully appreciate that a remap isn't just a "nice to have" however, i also believe that running with just my centre cat (de-cat up and downpipes) with a CEL fix for the downpipe and a resistor for the up-pipe will be ok on my WRX for now.

The main reason it causes issue on the STi is boost spike which is primarily due to the turbo, i've been assured and read in many places that the TD04 is unlikely to give this issue.

Going forward in the next 3-6 months i will be getting a remap, before this i want the headers ported, centre decat pipe and a new 255 fuel pump. The reason for this is safety and also that i know going for a decat will bring minimal gains in comparison to mapping suited to the mods....

In an ideal world (a richer one for me) i would be getting full decat, the fuel pump and a remap all in a couple of days but i can't afford it and i've read enough independent responses that say i should be fine with my current setup..... I don't drive the car that hard, not saying i'm doing performance mods for no apparent reason but i can't think of anytime i have booted it for more than 5 mins in the last couple of months, always run on optimax, will have a boost gauge fitted etc etc.....

[Rice Rocket]

For that reason Chris, do it in stages and you will see & feel the differnce in rermoving the cats one at a time.

I would be nice to be able to do al these things at once, but I have more to do with my money than have all latest and best things to be better than the next person.

Hey ho!

Ricey

[ANDYJDMSTI]

Now that you have shed more light i.e centre cat still in place then crack on.

 

[ally-b]

Hi Chris ,

ECUs are clever things []

It will put your CEL on to warn you that things ain't right . . . .  

so you fit a resistor in place of the probe to kid it that the fault/problem ain't there [:S]

But the ECU is smarter than that - it still knows that there is still a problem and adjusts ignition timing and fuel mixture to prevent engine damage . Infact it usually over-compensates by retarding ignition timing and richening the mixture to such extent that is is now producing less BHP and torque than before the 'modifications' were done !

Nice if you like wasting fuel ! . . . . . . it will pop and bang though , if that floats yer boat [8-)]

'Boost-spike' and overboosting will occur on any model which has been de-catted and not remapped , due to the turbo spooling faster and earlier than the standard ECU parameters . Yes, even the lowly TD04 []

Don't confuse this with 'boost-creep' which is a phenomenon specific to late STIs with the VF35 turbo , where the turbo wastegate port acts like a bottleneck - unable to vent excess pressure quicker than it is being produced , which causes boost pressure to 'creep' past the safety margin of 0.2Bar over max boost .

I see no point in making modifications for the sake of it - IE without gaining full potential by getting the mapping adjusted to suit your car.  .  .  .  and at the end of the day it is your car and your  money.

Ask yourself why ? you are making modifications . is it is to increase BHP and torque ? or is it so that it will just 'run' If it is to improve performance then do it once and do it right

My car was tuned on a v. tight budget , most parts used were second-hand but top quality . I saved money by doing a lot of the donkey-work myself . I also saved quite a bit by listening to those who had been there and done it before (Andy Forrest for example told me that some parts on my list were a waste of time and money , and also gave me some good tips about factors I'd not considered .eg: Plugs and induction hoses) . Don't try and cut corners - it will cost you in the long run .

Many of the guys here will tell you just how frustrating it is driving off-boost , with all your new goodies fitted , while you wait for the big-day to get the ECU mapped [:@] it is just sooooo tempting to floor it . But they will also tell you how much it was worth waiting for []

Also remember , once your car has been remapped , you own the software licence . It doesn't cost much to get the map 'tweaked' as new mods are added . 

I hope all this makes some sense and is of some help mate .

Al.

[jcscoob]

Hold off keep saving up the bits and bobs get it all done at once (including the remap) and you will be more than happy with the result, honest !!

Ps, its worth the wait . []

[ally-b]

Thats what I was trying to say , Jon []

lol

Al.

[jcscoob]

lol, []

[drb5]

Can't see how a decat up-pipe would make the car need a remap, on a 2001 UK WRX.

 

Do it all in one and enjoy the benefits....just so long as you do the CEL fix.

[wrxmania]

Hold off keep saving up the bits and bobs get it all done at once (including the remap) and you will be more than happy with the result, honest !!

Ps, its worth the wait . []

Thats' what I am doint - uncle Russell will be busy []

[Gumball]

. I would be nice to be able to do al these things at once, but I have more to do with my money than have all latest and best things to be better than the next person. Hey ho! Ricey

I dont.

But if i did, and im sure you would agree.............................

Do you put half effort into pole vaulting the missus? or do you give it maximum?

If i wanted to have better than other people i would wear a gold suit and drive a armoured hummer with gold bullions as brake pads.

I have the addiction to getting it as fast as i can and with that process i think of ways to get the power and still keep the engine in one piece.

easy tigress[]

[fai17]

If you can't do it all at once why don't you just save /collect all the bits that you think you'll need and fit them when you have them all ready.

That way you'll know your car is going to be safe and  not left with bits of engine because you can't be bothered waiting.

Think long and hard about this one as you'll know what's right for your car.

[chris_c201]

Ach now i'm totally confused!!

Who knows what i'll do!