Need Help with Cat Issue

[Corazey]

Hey Guys!

Here's my dilema...I've just finished the following repairs to my 05 LGT - New Turbo, Intake Hoses,Spark Plugs, Timing Belt, and EGR sensor. Now after all of that the car still sputters when it hits about 4,000 rpm Finally the mechanic tells me my catalytic converter is bad. Being that cost is really becoming a issue here's what i'm considering.
1- Buy a catless downpipe $200 (pros)Cheaper then catted DP (cons)Don't know thats where you guys come in ???? *I have a connection to still pass emmisions.
2- Gutting my Cats (Pros) A lot Cheaper (cons) ???????
I was thinking about the Megan DP since I have the Megan cat back exhaust. And what is the UP pipe for????

I dont want to have CEL on every time I drive cause I really like using my cruise control. Can anyone shed some light on the best option.

[Dookie]

Did you get your car retuned after replacing the turbo? Timing or air/fuel mixture could be off a little with the adding of a new turbo. One way to find out is do a data log. If you're not sure how to do this, let us know and we'll walk you through it.


1) If you have a connection to pass smog, go for the catless DP. This will get you closer to Stage 2.

2) You may gut the OEM DP, not a big issue.

3) You don't need the OEM UP. Subaru got rid of the UP on the '07 + models anyways. You'll have to delete the EGR on the UP, we have a simple fix for that if you decide to go this route. Pros: quicker turbo spool Cons: None


If you gut the DP, you'll need to get a Tune.

[Corazey]

I didnt know the car had to be re-tuned after changing those items, Where or who should I be looking for to get that done? And how much does it cost? I live in the Atlanta area. And how is the data log done?

Thanks for your help!

[TSi+WRX]

Go to an AutoZone or the like, they will pull (read) the code for you with their OBD-II scanner.

Whether your mechanic is right or wrong is a whole other matter, you need to first know what the code is saying - why your car is having trouble.

If all you've done is to replace stock parts with stock parts and your car is truly otherwise stock, then there should not be any problems - and truthfully speaking, I honestly don't think that a problem with the catalytic converter will cause such issues - a P0420, for-example, should not cause the symptom that you're reporting. Nevertheless, I also don't know what the *pre-turbo* cat in the UP - if it throws the UP EGT related code, would do.... This reason alone is one of many why you need to know what code your car's throwing.

And, of-course, there's also the question of what's really been done to your car. Did your mechanic say anything about the turbo that he/she replaced either not being a factory-stock component outright, or whether if it still looked factory, inside?

You know you've got brake mods and post-last-cat exhaust mods (from your other threads: https://www.legacygt.org/forums/showthread.php?t=2500 and https://www.legacygt.org/forums/showthread.php?t=2446), but what's really important is what your ECU is thinking. If it's been remapped for mods on your car that you hadn't seen (that the turbo has been re-worked internally or wasn't even stock, for example), then putting stock parts back on the car would cause all kinds of problems....

If you don't know what to do, at this point, it's a really steep learning curve - you might end up spending a lot of money and effort and still not get anywhere. The best thing may be to take your vehicle to an area speed-shop/tuner shop that actually knows what they're doing with Subarus, so that they can truly give your car a once-over and find out what all's been done to it.

[Dookie]

Good advice TSI, totally missed the engine code.


As TSI mention, 1st thing 1st, have someone pull any codes from your ECU with an OBDII scanner. This is going to be your starting point.


Once you figure out the issue, and still want to look into gutting your UP & DPs. Here are your options for tuning:

1) Accessport - A handheld device with preloaded "maps" to upload to your ECU. Prices very depending on new or used and the different preloaded maps. Price range from $400 - $800.
2) OpenSource Tuning - All you need is a laptop, VagCom cable and the free software. Here you will do the initial "data logging", email the data logs to an Etuner. The Etuner will adjust a new "map" based off your data logs. Then you'll Flash (upload) the new maps to the ECU. Price for an Etune $150 - $200.
3) ProTune - Find a local tuner in your area that is respected in the Subaru community. Prices usually start at $500.