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Old 04-19-2021, 06:25 PM   #1
G.rein80
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Default Performance mod questions

I'm def new to this. I just bought my first subaru impreza wrx and I must say its alot of fun to drive. I bought a mishimoto intake and a invidia catless downpipe. After I installed the downpipe it started to hesitate around 4k rpm and I don really feel the turbo kick in. If I got it pro tuned will the hesitation go away? Please help as this is driving me nuts
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Old 04-19-2021, 07:59 PM   #2
Ernest
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Downpipe needs a tune. Start reading the stickies before you mod. Or talk to a tuning shop.
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Old 04-19-2021, 08:29 PM   #3
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Remove both the intake and downpipe as soon as you can and keep them off until you can get it tuned. Stop modifying the car until you get more familiar on HOW to do it
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Old 04-19-2021, 10:05 PM   #4
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What year is your WRX?

Read the sticky threads at the top of this forum BEFORE hitting Buy It Now as you can't bolt stuff up to a modern car like your Cousin Jimmy does to his old Camaro!
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Old 04-20-2021, 06:48 PM   #5
G.rein80
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First off whats a sticki? 2nd I bought everything for my car before I joined this. I was told that the downpipe wouldn't require a tune, but I guess that info was incorrect. And if I knew people were gonna be smart asses about my question I wouldn't have posted it. I did the similar mods a long time ago to my mustang and it didn't require a tune.
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Old 04-20-2021, 06:50 PM   #6
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I don't have a cousin Jimmy so I don't know if u got me confused with someone else or not. My sub is a 2010
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Old 04-20-2021, 06:53 PM   #7
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I talked to a tune shop and they said that a cobb v3 access port would fix what I have going on, is that true? O r did that guy give me false info
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Old 04-20-2021, 07:33 PM   #8
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Quote:
Originally Posted by G.rein80 View Post
I talked to a tune shop and they said that a cobb v3 access port would fix what I have going on, is that true? O r did that guy give me false info
He's both right and wrong. You need the accessport and THEN get a tune for it, which will cost you another $400+.
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Old 04-20-2021, 07:38 PM   #9
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The Cobb access port is needed to flash the STG 2 for the downpipe .you need to use a stock intake with Cobb tuning maps ... The Mishimoto intake shouldn't be used ...
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Old 04-20-2021, 07:46 PM   #10
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Quote:
Originally Posted by Ernest View Post
Downpipe needs a tune. Start reading the stickies before you mod. Or talk to a tuning shop.
What the hell r stickies? I also just joined this site yesterday so I'm still trying to figure this out to. I talked to a tune shop today but I don't know if the info he told me is correct. The guy told me that a cobb v3 access port would fix my issue, but he didn't sound to sure of himself.
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Old 04-20-2021, 07:50 PM   #11
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Quote:
Originally Posted by blue sedan View Post
The Cobb access port is needed to flash the STG 2 for the downpipe .you need to use a stock intake with Cobb tuning maps ... The Mishimoto intake shouldn't be used ...
Why cant the mishimoto be used? This is why I joined this site because the people on here sound like they know what there talking about. A guy I work with told me **** completely different which is why I won't listen to him anymore
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Old 04-20-2021, 07:51 PM   #12
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Quote:
Originally Posted by carsebuco View Post
He's both right and wrong. You need the accessport and THEN get a tune for it, which will cost you another $400+.
He said the Cobb will tune for the downpipe
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Old 04-20-2021, 07:56 PM   #13
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Quote:
Originally Posted by carsebuco View Post
He's both right and wrong. You need the accessport and THEN get a tune for it, which will cost you another $400+.
He said the Cobb will tune for the downpipe. So what exactly does the cobb accessport do then?
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Old 04-20-2021, 08:06 PM   #14
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Default Performance mod questions

The AP allows someone to modify the OEM ECU rom. OTS maps are a generic modified map within certain parameters for specific modifications. Pro-tune is a custom tune specifically for your car, fuel quality, modifications, elevation, etc, etc. Either way, the AP is simply allowing for the ECU to have its parameters changed.

Haven't really been following this thread, but the gist of what I'm seeing is understanding what modifications to use with an OTS map. Here's an easy way to look at it. If you put parts A, B, and C on your car and go to your local tuner for a custom tune, then you are tuned for those parts. If you then add part D you'll need a new tune. Or let's say part A is the turbo, change the model of the turbo and you need a new tune.

Now let's say you are trying to use Cobb's stage 2 OTS map. There's a list of parts Cobb says you need for that map to work properly with your car. If you follow that parts list then they say your car will function properly because that's a "custom" tune for those parts. I say "custom" because it's a generic map but it's still a modified map that's no longer OEM and therefore created specifically for those parts.

Now, do you need to use Cobb's down pipe on their stage 2 map, no. As long as it's a catted 3" down pipe it will work. But go catless and that map isn't correct any more. Add an ELH, wrong map. So even though there are some gray areas in those OTS maps, the margins for error are very small and you don't want to venture far from the recommended parts. For instance, stage 2+ calls for Cobb's EBCS. I wouldn't use a GrimmSpeed EBCS and expect that map to function properly. Hope this all makes sense.

Last edited by snow_bound26; 04-20-2021 at 08:18 PM.
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Old 04-20-2021, 08:55 PM   #15
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I have vast Mustang knowledge, having built a Factory Five Cobra using a 96 Explorer engine with the Mass air from a Mustang, and an E303 cam. Mustang engines run about 50% of what they are capable of. Low revs, low cam lift and duration, restricted intakes. The factory ECU allows a really wide range of things to make the engine breathe better, allowing way more fuel.

A Subaru is not this. The ECU tune has a relatively narrow band in which it works. It's expecting the factory well designed cold air intake. Put on some cone filter and you're increasing intake temperature and changing what the MAF sensor sees. This throws off what the Subaru thinks is coming in for air. It really screws things up. Where the Mustang doesn't care, the Subaru can become dangerously out of tune and do it long enough and you can destroy your engine. On the other end of things, remove the cats on a Mustang....heck....run the engine with no exhaust manifold and it'll run fine. I've done it. I have pictures of me and my son when he was 4 in a chainsaw helmet in the "go kart" chassis with engine from the factory five with no exhaust driving around. It's loud and cool and runs fine. Ok...do that with a Subaru and it can't adjust with the stock tune (except 02 and 03) wnd it'll go lean. Real lean. And then.....(you get to guess here). Ok...did you guess that you destroy your engine? Good.

The good news is that guys that tune these things can change the values stored in the ECU to match the stuff you've done to your car. But what you need to do is put on the stuff and drive to that tuner WITHOUT GOING INTO BOOST AT ALL. Then the tuner will put in a base map for what YOUR car is set up with. Then he'll run it on a dyno or while you drive and he laptops and see what your car is doing with these values. When he's done, your car will drive safe and be fine. But if you decide to later go to bigger injectors, you need to go back and tune again.

The short story is that almost anything you do to the engine of a Subaru requires a tune.
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Old 04-20-2021, 09:08 PM   #16
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Let's start over. The sticky's (located above the new threads) are threads about certain subjects that have excellent information that is extremely helpful to new forum members. Read those first.

In order to best help you please tell us the year of your car and is it a stick or auto, and go to the Cobb website, put in your cars information and see the products for your car. The info on the AP will tell you what parts you need to make the AP work with your car. You won't need a tuner if you use their parts, just the correct OTS (OFF THE SHELF) program you'll need to download. As others have said, if you deviate from the listed parts then you will need a professional tune.
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Old 04-21-2021, 12:19 AM   #17
Diavolo_
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Quote:
Originally Posted by G.rein80 View Post
Why cant the mishimoto be used?
it makes a drastic change in the intake system.
it can not be used because there is no map on your accessport which includes an adjustment for that part.
Off the shelf (generic) maps, do not factor for that part.

the intake can be used if you have a custom tune made for your car which takes that part into account.


basically stage 1, is all stock and just changes the software.
stage 2 is all stock except change the downpipe to a compatible one for the map.
Cobb does have some maps that include their other parts.
the above are all generic maps.
any other mods need a custom tune.

if you put different hardware on your car the generic maps wont function as intended, and you will have to have a custom map made for the mods you add.
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Old 04-21-2021, 03:54 PM   #18
G.rein80
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Quote:
Originally Posted by snow_bound26 View Post
The AP allows someone to modify the OEM ECU rom. OTS maps are a generic modified map within certain parameters for specific modifications. Pro-tune is a custom tune specifically for your car, fuel quality, modifications, elevation, etc, etc. Either way, the AP is simply allowing for the ECU to have its parameters changed.

Haven't really been following this thread, but the gist of what I'm seeing is understanding what modifications to use with an OTS map. Here's an easy way to look at it. If you put parts A, B, and C on your car and go to your local tuner for a custom tune, then you are tuned for those parts. If you then add part D you'll need a new tune. Or let's say part A is the turbo, change the model of the turbo and you need a new tune.

Now let's say you are trying to use Cobb's stage 2 OTS map. There's a list of parts Cobb says you need for that map to work properly with your car. If you follow that parts list then they say your car will function properly because that's a "custom" tune for those parts. I say "custom" because it's a generic map but it's still a modified map that's no longer OEM and therefore created specifically for those parts.

Now, do you need to use Cobb's down pipe on their stage 2 map, no. As long as it's a catted 3" down pipe it will work. But go catless and that map isn't correct any more. Add an ELH, wrong map. So even though there are some gray areas in those OTS maps, the margins for error are very small and you don't want to venture far from the recommended parts. For instance, stage 2+ calls for Cobb's EBCS. I wouldn't use a GrimmSpeed EBCS and expect that map to function properly. Hope this all makes sense.
I appreciate all ur info thanx
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Old 04-21-2021, 04:11 PM   #19
Notbrick
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This will give you about a weeks worth of reading alone, and well worth it. While Subarus are fantastic, they are also quite particular. Any advice coming from members here with a long join date, is most often than not a good person to at least pay attention too. Those who don't, unfortunately can see their Subaru go kablang. It's the reason my car has remained completely stock.

Anyway:https://forums.nasioc.com/forums/sho...hreadid=533787
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Old 04-21-2021, 05:05 PM   #20
Ernest
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As stated above. Get the Acesssport and use the correct off the shelf tunes for your mods. Drive and enjoy. If you think you are done modding maybe an e-tune or pro tune.
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Old 04-23-2021, 04:08 PM   #21
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The hesitation you're describing is probably being caused by the OEM fuel pressure regulator.

Cobb used to sell a kit but it looks like is discontinued.
It was called COBB Tuning Fuel Pressure Regulator Kit - Subaru STI 2008+
Part Number: COB315200
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Old 04-28-2021, 11:12 AM   #22
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you will need a tune for air intake and downpipe. Cobb accessport will be needed, but it's only one part of the tuning equation. Cobb does offer some free off the shelf tunes (referred to as OTS), but they are normally very specific in terms of the part, mainly their own brand since they know the exact spec and tune for it. Also with emissions cracking down they are in the process of revising tunes and parts to go along with those tunes, so the off the shelf tunes are super limited right now.

With that being said, almost everyone will highly recommend an e-tune or pro-tune, simply because it will be specific to your car, your weather conditions, driving habits, etc.

these cars stock are maf based, so any drastic change in flow can do some damage, my best advice, take those parts off and return to stock. after that, do some digging and try to plan the modifications and tuning accordingly with your budget. Phatbotti's website has some suggested info. I would recommend starting there.
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Old 05-01-2021, 02:20 AM   #23
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Quote:
Originally Posted by G.rein80 View Post
First off whats a sticki? 2nd I bought everything for my car before I joined this. I was told that the downpipe wouldn't require a tune, but I guess that info was incorrect. And if I knew people were gonna be smart asses about my question I wouldn't have posted it. I did the similar mods a long time ago to my mustang and it didn't require a tune.
Catback exhaust dont require a tune although it is recommended. but anything past the cat will definitely need to be tuned
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