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Intake issue on a 2013 wrx

19K views 57 replies 21 participants last post by  Mikie13 
#1 ·
first of all I am not sure if this is the right spot for this thread, if it isnt please slander me on the internet until the end of time, or till i fix it and put it in the right spot, but if it is the right spot then :thumbup:

So this is whats going on, i just got a new Cobb SF shot ram intake for my 2013 wrx, install went easy but my car does not like the intake at all, at higher RPM's it stutters and runs rough, double checked everything, disconnected the battery during install, so im not sure whats going on. anyone have any ideas? i remember seeing someone saying that if you install anything you should get your ecu tuned to work with it, i didnt think that installing a intake would make my car run that bad ~_~
mind you my other cars i worked on was a 95 GS-T Eclipse and a 2004 wrx which both took the new intakes like champs. so any help to this issue would be great, thanks all!
 
#4 ·
You absolutely must tune for an intake on the 3rd gen cars.

That said, it almost sounds like there could have been a leak too.
 
#7 ·
Cobb has stated that a tune is not required for their intake but highly recommended to get the power gains of the intake. Rallysport direct says the same. As long as the intake has the same size Maf tube it'll be ok but I still recommend a tune to get the performance gains of the intake.
 
#27 ·
Bah, I hate when I miss threads and have to quote 30 people.

I'd like to start off saying that I'm a huge fan of saying that an intake really should have a tune on the newer cars.

1.) By default, once you hit open loop fueling, it continues to apply a learning trim percentage fuel trim that was learned in a normally lower load range (depending on your tune, of course). The percentage does not apply evenly across loads. For example, at idle, you may need a 3% correction to get to a stoich mixture in eyes of the ECU. At wide open throttle (WOT), that 3% difference can mean the difference between 11afr and about 11.5afr. I know the car won't apply the trim learned at idle (low load range) to the WOT range, but the same issue occurs over the range of A/F Learning D.

2.) Boost response. I'm not sure of the effects of the intake directly on your cars boost response. I'd bet that the turbo is more responsive, and possibly at the limits of the ECUs turbo dynamics tables - meaning the ECU is maxing out it's boost correction ability. This shouldn't cause the "system lean" code, however.

3.) Slight differences between intake systems.. even with the same "MAF housing diameter". Every intake handles air a bit differently at various speeds. My KSTech intake (stock sized MAF housing) looked great as far as A/F learning & correction went at lower loads. It was in the 2.0+ load range where I started to see some fairly substantial variances from the stock intake. I may be able to kick up a graph somewhere or dig through for my scaling changes. For the record, A/F Learning D would never have picked up those differences since I would have been in open loop fueling long before that load range. This could cause a "system lean" issue.

4.) Everything else aside, the intake could have a mechanical problem associated with it. Boost/vacuum leaks aren't uncommon. Putting the MAF sensor in backwards is not unheard of (even though it doesn't in that direction I believe). If it is an oiled filter... the MAF could be oiled as well now.

Keep in mind, all cars are using a generic tune from the factory. Your car may have been at the very edge of that tune (for better or worse). The more you modify your car, the further you risk leaving that nice "generic" WRX that Subaru used to generate their tunes.



That being said:


I could see merit in that statement. I disagree the MAF scaling will be the same. Whether it is dangerously far off, who knows. It's easy to verify that with a wideband o2 and both intakes.


You can run the SF intake without a tune and it will be fine. But it provide no performance gains and be a just a noise maker until tuned.
Not every car is a like. Nor is every mechanic. For whatever reason, the OP had issues regarding his. Whether it was directly caused by the intake, we don't know, but we can speculate.


Do you have a wideband O2 sensor installed? If not, you cannot make this judgement. A "System too lean" can mean a number of things.
Yup. Especially in those load ranges. The narrowband sensor becomes useless once you hit boost.... which is where you start to care that your afrs are out of comfortable range.


And how does this mean a number of things? It's an in your face answer. It's a 2013. Not a 1993, what the hell else could it be???
Could mean various things. I'm not up to snuff with the "system lean" code, but for example, look at adding a high flow down pipe. That throws codes which appear to be "in your face answers"... when they really aren't. Poor catalytic converter efficiency could be triggered by having additional air passing the rear o2 sensor, as opposed to having 'polluted' air passing the rear o2 sensor. These codes are assuming a car with stock hardware. They are allowed to make assumptions when they build the car.


The SF absolutely requires a tune. I have a 2013 (purchased 9/28/12), and ordered the SF plus air box, Cobb downpipe, AP, and some other goodies....all in anticipation of OTS tunes. Got a little anxious, and after the 1000 mile break in, installed the intake just to see what I see. At around 4K, the car ramps up to a little over 17 psi, hits the overboost fuel cut, and stutters for a sec or two before it adjusts and picks back up (just like you're experiencing, I'm sure). The ECU is reading so much more air it has no idea what to do, so it cuts fuel and boost. Just stay out of boost, and it will drive fine, or do like advised and re-install the factory parts for a few more weeks. It took roughly 1 month for Cobb to release the first OTS maps for the 2012, so i'm anticipating roughly the same (though I really have no idea).
That's quite over confident, as stated. While I have my opinions on the matter, these cars always manage to surprise me somehow.

You'll know when the ECU is reading too much air though. You'll get a "MAF sensor" OBDII code... showing you pulled 5V on the sensor. You won't hit that with an intake unless you've fouled up the MAF sensor. Which I have in my experience. Every time it rained or I got my car washed and hit boost that'd happen. Otherwise... the ECU will use it's highest load range values for timing/fueling/etc when it runs off of the table in the tune. You shouldn't be running that far off the table for it to make a huge impact.

Over boosting is a legit issue though. I thought whenever it through a fuel cut of any sorts you got an OBDII reminder, however. Tuning a catless car with the IWG makes you very familiar with this OBDII code. There are some 'soft' boost cuts to my understanding. If you pick up X amount of detonation, the car will pull boost to the best of it's abilities (normally 7 psi). I don't know whether a detonation invoked boost cut throws a code.


I see this stated with absolution, feeling your confidence, and yet I see no supporting data. So lets dispense with the opinions and accept this entirely as speculation. Now, if someone with a 2010+ (Shawn Mangan to the front please) would please load the Stage 1 map with Stock Airbox and Stage 1 map with SF intake and lets have a look at the MAF scaling.
Correlation =/= Causation
I will dig up an example of my KSTech intake vs the stock if I can find it. They claimed it didn't need a tune due to the same diameter MAF housing. It did. Cobb I am sure put in some additional engineering time though.


I wish no manufacturer would claim that their intakes are "stock tune safe". Stop wasting engineering time on them... put a tube with a smooth MAF curve together.. and sell it for cheaper. You really should get a wide band o2 once you start altering air/fuel values in a car outside of manufacturer specs in my opinion. You are a blind man otherwise.
 
#8 ·
I doubt it's the intake. Cobb has designed the SF intake to mimic the airflow of the stock intake across MAF sensor. Are you sure that you installed the MAF correctly (not backwards) and that it's connected? Any CELs?
 
#13 ·
Do you have a wideband O2 sensor installed? If not, you cannot make this judgement. A "System too lean" can mean a number of things.
 
#20 · (Edited)
The SF absolutely requires a tune. I have a 2013 (purchased 9/28/12), and ordered the SF plus air box, Cobb downpipe, AP, and some other goodies....all in anticipation of OTS tunes. Got a little anxious, and after the 1000 mile break in, installed the intake just to see what I see. At around 4K, the car ramps up to a little over 17 psi, hits the overboost fuel cut, and stutters for a sec or two before it adjusts and picks back up (just like you're experiencing, I'm sure). The ECU is reading so much more air it has no idea what to do, so it cuts fuel and boost. Just stay out of boost, and it will drive fine, or do like advised and re-install the factory parts for a few more weeks. It took roughly 1 month for Cobb to release the first OTS maps for the 2012, so i'm anticipating roughly the same (though I really have no idea).
 
#21 ·
The SF absolutely requires a tune.
I see this stated with absolution, feeling your confidence, and yet I see no supporting data. So lets dispense with the opinions and accept this entirely as speculation. Now, if someone with a 2010+ (Shawn Mangan to the front please) would please load the Stage 1 map with Stock Airbox and Stage 1 map with SF intake and lets have a look at the MAF scaling.
 
#22 ·
Sorry, I should rephrase.....My particular WRX, with a SF plus air box, requires tuning to run properly. Disclaimer: I can not predict how yours will run, results my vary.

That said, anecdotal evidence supports tuning is not only suggested, but required.
 
#24 ·
True enough, one does not imply the other. However, while only changing one variable (the intake), one can deduce that the intake is directly related to poor performance and current condition.

But you are correct, I have no MAF tables to prove this....I will have to wait for tuning to become available, then I'll report back.
 
#25 ·
FWIW, I'm not arguing that one should not tune for an intake. If you reread my previous posts, you'd realize I am 100% an advocate of the "you install a part, you tune for the change" philosophy. However, I'm not convinced that the SF intake (which has been designed to mimic stock airflow characteristics, thus allowing AFR Learning to account for the extra air) causes the car to run dangerously lean to the point of potential engine damage. OTOH, if supporting data can be provided, I will gladly change my perception.
 
#26 ·
Nor am I arguing. I am certainly no tuning expert, a novice in fact. I don't think a dangerously lean condition is occurring either, but something is happening. With stock air box, boost peaked at 15, and would taper down quickly to the set point of 14.2. With the SF intake, it now peaks at slightly over 17, at which point the stuttering occurs, which Cobb techs (on their forums) explain as the overboost fuel cut. This only happens at WOT, mind you, when peak boost can be achieved. Modest acceleration is ok, but where's the fun in that!?!
 
#29 ·
I'm not going to the trouble to read.. but I can tell you what I would and wouldn't do. I wouldn't change intakes on my car without data logging (no matter which intake it is). And if I saw something in the logs I didn't like, I would have the car tuned.. honestly, I would have the car tuned for the intake regardless, otherwise what's the point of installing it? But I certainly would not just run an intake without at least pulling a few logs to make sure it's okay, and I would never recommend someone else to do so.
 
#32 ·
All aftermarket intakes for 08+ Subarus require tuning, regardless of manufacturer, in order to ensure the MAF sensor reads properly and the engine operates within safe parameters.
;).

vu_tang... Donkey is suggesting you re-evaluate your statement. It isn't that the "ECU doesn't know what to do with the extra air"
 
#34 ·
Do you have the intake that this thread is concerning? I assume not since you said stock. That is not normal, however. Maybe try another dealer.
 
#36 ·
first of all I am not sure if this is the right spot for this thread, if it isnt please slander me on the internet until the end of time, or till i fix it and put it in the right spot, but if it is the right spot then :thumbup:

So this is whats going on, i just got a new Cobb SF shot ram intake for my 2013 wrx, install went easy but my car does not like the intake at all, at higher RPM's it stutters and runs rough, double checked everything, disconnected the battery during install, so im not sure whats going on. anyone have any ideas? i remember seeing someone saying that if you install anything you should get your ecu tuned to work with it, i didnt think that installing a intake would make my car run that bad ~_~
mind you my other cars i worked on was a 95 GS-T Eclipse and a 2004 wrx which both took the new intakes like champs. so any help to this issue would be great, thanks all![/QUOTe


If you dont have the accessport it wont run right your tuned to your stock air box and now that you opened it up your air fuel is way off.....do you have an air Fuel Gauge in your car? if not it might be a good idea to get one then you will know exactly where you are at at all times.....do it now and see the comparison before and after you flash the accessport. cobb makes a great tune for that intake already flashable its a preloaded basemap you can also download different basemaps of there sight as well the more you do but will not be as accurate or nearly a consistent as throwing it on a dyno if you can find a tuner with accesstuner pro around your area anyywhere it would even be more consistant....but ya your issue is your ecu you just have to tune it to coincide with whatever you do to the car mechanically... and thats with everything .... including something as simple as an intake or exhaust... especially exhaust thats why you hear some subies pop alot on decels because they dont have it tuned....get yourself a boost/vacc gauge and an airfuel ratio gauge so you can monitor what your car is really doing and just remember when you buy them with gauges you get what you pay for and that includes the readings they are going to give you and how accurate they are...
 
#37 ·
Holy old thread, Batman.

Tune for any mod, simple as that.

Guessing the OP has figured that out by now, and is enjoying at least Stage 1.
 
#38 ·
first of all I am not sure if this is the right spot for this thread, if it isnt please slander me on the internet until the end of time, or till i fix it and put it in the right spot, but if it is the right spot then :thumbup:

So this is whats going on, i just got a new Cobb SF shot ram intake for my 2013 wrx, install went easy but my car does not like the intake at all, at higher RPM's it stutters and runs rough, double checked everything, disconnected the battery during install, so im not sure whats going on. anyone have any ideas? i remember seeing someone saying that if you install anything you should get your ecu tuned to work with it, i didnt think that installing a intake would make my car run that bad ~_~
mind you my other cars i worked on was a 95 GS-T Eclipse and a 2004 wrx which both took the new intakes like champs. so any help to this issue would be great, thanks all![/QUOTe


If you dont have the accessport it wont run right your tuned to your stock air box and now that you opened it up your air fuel is way off.....do you have an air Fuel Gauge in your car? if not it might be a good idea to get one then you will know exactly where you are at at all times.....do it now and see the comparison before and after you flash the accessport. cobb makes a great tune for that intake already flashable its a preloaded basemap you can also download different basemaps of there sight as well the more you do but will not be as accurate or nearly a consistent as throwing it on a dyno if you can find a tuner with accesstuner pro around your area anyywhere it would even be more consistant....but ya your issue is your ecu you just have to tune it to coincide with whatever you do to the car mechanically... and thats with everything .... including something as simple as an intake or exhaust... especially exhaust thats why you hear some subies pop alot on decels because they dont have it tuned....get yourself a boost/vacc gauge and an airfuel ratio gauge so you can monitor what your car is really doing and just remember when you buy them with gauges you get what you pay for and that includes the readings they are going to give you and how accurate they are...
Yeaaaaaaaaah...late bump much?

Your information is a bit skewed. Regular A/F gauges are a waste. You don't get anything from a cheapo A/F gauge. You need a Wideband gauge to get any useable info. You do not need to tune for a regular CBE or Axleback. TBE/Downpipe? Most certainly. Intake? Yes...while OTS maps where you follow the map notes are plenty sufficient, you do leave some possible gains on the table as opposed to a full on protune.
 
#39 ·
i had the same issue with my 2013 even with a cobb app heres the simple solutions without a protune and jumping into crazy amount of money

1.remove it

2. get the cobb app with a super low wastegate map (only a stage 1)

3. if your running a stage 2 you will overboost somewhere near 19 pound 18 on a slwg youll hit these numbers around 5500 rmps in 4th your 1st through 3rd gear are incredible but 4th and 5th wide open throttles will cause the same issue

4. sell it get a aem or k &N with a slwg and you'll hit around 17 just put a aem on mine tonight did my runs and all great :)
 
#40 ·
3. if your running a stage 2 you will overboost somewhere near 19 pound 18 on a slwg youll hit these numbers around 5500 rmps in 4th your 1st through 3rd gear are incredible but 4th and 5th wide open throttles will cause the same issue
This depends on the car! Just because your car requires the lower WGDC tables doesn't mean the OP's car will.
 
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