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 Post subject: Some advice in tuning for catted downpipe
PostPosted: Wed Nov 01, 2017 3:48 pm 
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Joined: Wed Nov 01, 2017 2:54 pm
Posts: 2
Hey guys,

First of all I'd like to thank all of the nice people in this forum providing so many "How-to´s", Guides and a lot of bits of information which really helped me to get any idea of ECU tuning. :D

I'm new to this and haven't really done any ECU tuning in the past. I mostly worked with bolt-on parts and/or went to a professional tuner. I recently got my hands on a USDM 2006 STI which was giving me headaches with CELs caused by a faulty EVAP valve. So I got myself a Tactrix cable to disable this pesky CEL code, without having really the intention on tuning the car with it. But after seeing how easy it was to read, edit and flash a ROM I got curious and started a bit of digging.

I would like to start of my deeper learning process with what I think is a rather easy modification. I intend to get the Invidia catted downpipe for my STI to complement my Invidia Q300 catback exhaust. I read that boost spikes/overboosting can be an issue when adding a 3" downpipe and removing the restrictions of the OEM ceramic cats. Meaning the car needs to be tuned for it, so this mod can safely unfold its potential. :mrgreen:

Can someone point me in the right direction from where to start on editing the ROM to account for a bigger, catted downpipe :?:

Some car facts:

03/2006 USDM STI
ECU A2ZJE11J
Exhaust: Invidia Q300 cat back and future Invidia Downpipe
No other engine mods


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 Post subject: Re: Some advice in tuning for catted downpipe
PostPosted: Thu Nov 02, 2017 5:17 am 
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Joined: Sat Jul 06, 2013 8:55 am
Posts: 2038
Location: NI
read, read, read again and you'll do OK - start with how the boost control system works:
http://www.romraider.com/forum/topic1814.html

Next mission will be to come up with a new target boost value - .1 or .2 bar over what you have now will be sufficient but on the standard engine try and keep it around 1.3 bar to maintain the piston rings. Also you'll need a way to monitor the fuelling so a decent wideband O2 sensor is needed (AEM UEGO, Innovate MTX-L, Zeitronix ZT-2 etc.). Even at standard boost levels some gains can be had simply by playing with the fuel and timing to optimise the car for your available fuel supply.

Along with your downpipe, also consider a good quality panel filter in the standard airbox along with an aftermarket fuel pump that can keep up with the demand for fuel that comes with increasing the boost levels.

_________________
Good luck and may the logs be ever in your favour!


MY06 EDM STi Type UK Spec D
============================
Panel Filter/2.5" Decat/Prodrive Springs/Leather Seats


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 Post subject: Re: Some advice in tuning for catted downpipe
PostPosted: Mon Nov 13, 2017 3:35 am 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2428
Tuning boost is easier with an aftermarket boost control solenoid, so I suggest ordering one.

1) Read this, if you haven't already: viewtopic.php?f=33&t=5384
2) Make some data logs of WOT pulls from 2500 RPM to the rev limit. If they're healthy, then go to step 3. By "healthy" I mean you usually don't see any knock during a pull. If you do see knock - especially if you see knock the same RPM/load area - then reduce timing or add fuel to make the knock go away. (If reducing timing and adding fuel doesn't make the knock go away, it might be false knock.)
3) Set your maximum WGDC to 0%, and do some WOT pulls from 2500 to the rev limit. This will tell you how much boost you get with the wastegate sprint alone. if you have knock, fix it as describe above.
4) Install the aftermarket solenoid.
5) Tune your boost back up to whatever boost you're running today (as shown in the first set of logs). The goal here is just to learn to tune boost, without the distraction of tuning fuel and timing at the same time.
6) Flash back to 0% WGDC.
7) Install the new downpipe.
8 ) Tune your boost back up to whatever you're running today. It'll be a little different than in step 5 because of the better downpipe. It will take a little bit less WGDC to hit the same boost levels. You'll build boost a little faster, so you'll probably hit some fueling/timing cells that you didn't hit before. Make sure they don't knock.
9) Tune your boost a little higher than it is today. Now you're definitely going to hit some new fueling and timing cells. I'd keep the AFR the same (the stock tune runs pretty rich, no need to go richer), and just reduce timing (more load requires less timing).

That won't necessarily give you the best tune, but it does give you a pretty straightforward path to producing a good tune. By the time you're done with that process you'll probably be comfortable optimizing the tune further. Or at least you'll have new questions to ask about what to do next. :)

Also read this: http://www.romraider.com/RomRaider/Inco ... deToTuning

_________________
2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, BC 272, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: Some advice in tuning for catted downpipe
PostPosted: Tue Nov 21, 2017 5:42 am 
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Joined: Wed Nov 01, 2017 2:54 pm
Posts: 2
Thanks guys for your suggestion! So next thing I will do is getting a wideband and a BCS. And then start fiddeling with the tune. But first I need to take care of some rust pockets on the rear quarter panels :shock:


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