Which Subaru Parts Require a Tune?

Our question of the week this week is one that comes up somewhat often. What parts require a tune? And why does it seem that you have to tune your Subaru for every part that you want to install?
Do I need a tune if I put on an intake?
Do I need a tune if I put on a bigger intercooler?
And if so, why?
A lot of this comes down to the way that Subaru engines measure the air that is going into the engine, and we go into detail about that for this video.
It is also worth mentioning that we recorded this video before the recent changes to the Cobb Access Tuner and Cobb AccessPort, so this is a more general discussion, not a discussion focused on those changes.
But rest assured, we are working on a video specifically about that now too.
Thanks for watching and Stay Tuned!
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[@zachscott4867]

Thank you to you guys for providing a well directed conversation about the Subaru journey. So many things to learn and accurate, concise, and experience driven content helps a lot of people improve their game. Just put a factory block in a 05 LGT wagon! Full send gentleman!

[@FlatironsTuning]

Thanks very much for the comment. Really appreciate that! Stay Tuned!

[@nrw510]

The way Jon explains the MAF is extremely important. I first learned this from MRT performance KZbin. Those guys are from Australia and they said that's the #1 mistake people make

[@FlatironsTuning]

Thanks for the comment! Stay Tuned!

[@marvinvisser5039]

This should be a video every Subaru owner that is interested in putting a modification on their car should look at 👏

[@FlatironsTuning]

Thanks very much. Really appreciate that. Stay Tuned!

[@bluegizmo1983]

Thats weird, because I just bought a subaru that has an upgraded turbo (vf39), STI TMIC, Perrin intake tube, TGV deletes, aftermarket downpipe with no cats, and an STI catless up-pipe, and although the ECU has been tuned for timing, higher boost, and open loop target AFR, the MAF scaling has never been touched (verified against a stock oem tune for the same year vehicle) and yet the actual AFR readings are spot on what the they should be.

[@benjurmind1318]

This is a powerful video. I've heard of Speed Density but I didn't really know it was in parallels to a MAF sensor like that. Pretty eye opening to think about when observing different engine setups.

[@benjurmind1318]

*Parallels in the sense that it's like some cars use a MAF to calc. airflow while other cars use Speed Density.

[@FlatironsTuning]

Thanks very much for the comment! Definitely take a look at our video detailing the difference between MAF and Speed Density too. here is a link to that: kzbin.info/www/bejne/rJzKo5RtndVse68 Thanks for watching and Stay Tuned!

[@thomasmurphy5906]

Makes sense to me, excellent break down

[@FlatironsTuning]

Thanks for watching and Stay Tuned!

[@kristofferkennethjimenez3536]

Hey guys! Thanks for a great video! Question regarding replacement of hoses along the intake track such as BOV recirculating hose, turbo to intercooler outlet, throttle body hose, purge valve vaccum hoses, boost solenoid turbo and intake side hoses. Is a tune/retune reuqired when these hoses are replaced? What are the considerations to be taken in to account when using afternoon silicone hose instead of oem as replacements. Thank you!

[@ytdweller23]

Thanks guys for every effort you make. Two questions please: 1- How safe is it to drive the car (intake & downpipe installed) without a tune, in an intention to tune it later on (while avoiding pedal to the metal) ? and how long is it okay to stay untuned? 2- As far as I understand when it comes to tuning, the cruciality boils down to air/fuel ratio more than gaining extra horsepower; meaning to get the car to a safe chemical composition is the core idea of tuning more than squeezing as many horsepower as possible out of the engine, correct?

[@FlatironsTuning]

Thanks for your question. For part 1, when you are talking about an intake, there really isn't any safe distance to drive if you don't have the correct calibration on the car for the intake you are running. Damage can occur somewhat quickly with that issue, and it is not recommended. A downpipe is a bit less of an issue, but it can lead to an overboosting issue which presents its own set of problems. The best practice is to drive your car as little as possible without the proper calibration, and never to drive with an intake that hasn't been calibrated for. Part 2, I would say that in terms of safety, you are about right, but there is more to tuning than just making sure that your AFR's are correct. I'd recommend going through our video talking about what a tune does here: kzbin.info/www/bejne/qXu0d6KImq6ld5Y Thanks for watching and Stay Tuned!

[@ytdweller23]

@@FlatironsTuning Thank you again for this elaborated, professional and satisfying answer. This channel has never disappointed me.

[@RyanDouglas1987]

What tuning is possible? Limp mode with flashing cruise light and check engine light. How do you tune with these?

[@420turbos]

Great talk gentlemen! I have a few questions i hope you would donate your thoughts to. Thoughts on drop in air filters like aem, k&n, ect... and tuning? Installing a avo top mount intercooler on my 2012 wrx with a drop in aem filter, and spt cat back. I have a cobb access port with the stage 0 tune loaded. Do you think I am good to add the intercooler and stay with the stage 0 tune?

[@FlatironsTuning]

That is a tough question. On the newer cars, in theory, they are more likely to need a tune with a drop in filter than some of the older ones. The best advice is to monitor and log your car after making the changes (and ideally have logs from before to compare against) to see how different they might be, and that will tell you if the ECU is getting close to a limit, or having to adapt to the changes. If you see a significant difference after putting on the intercooler and filter, then you would need to get a tune. You could also have your tuner do a simple baseline after putting the parts on to check power and the running of the car, and they will be able to tell you if you need a calibration adjustment as well. Hope that helps and Stay Tuned!

[@Mike_44]

What do you mean by small changes to the I/C? I’m planning on getting an aftermarket I/C. Does this then require a tune? Thanks for another great video..

[@FlatironsTuning]

Thanks for your question. If you are moving to an aftermarket intercooler that is close in performance to the stock intercooler, then you may not need a tune. Ideally you would want to take some logs or monitor your Air Fuel ratios to make sure that everything is still working properly. If you are moving to a more efficient intercooler core, it is ideal to tune the car to make sure that it is running properly, and to make sure that you are getting the full benefit of the better intercooler. Thanks for watching and Stay Tuned!

[@TheZohanLohan]

Some other mods that don't need a tune for EJs are turbo inlets, post maf hose and fuel rails. But if you're doing those there's probably something else you're doing that will require a tune anyways lol

[@yowie0889]

Go-fast brand stickers always need a tune however.

[@FlatironsTuning]

Good points. Thanks for the comment and Stay Tuned!

[@ryanjones7202]

So I wanna get a 2022 wrx with a cvt (I know stupid but its what fits my needs) but I want an axleback and an intake just for the sound and could care less about performance gains from it but didnt know if it would void my warranty and if Id need a tune for it. Amy advice would be helpful!

[@FlatironsTuning]

Thanks for your question. The axleback will not have an impact on your warranty, but the intake likely will. Hope that helps and Stay Tuned!

[@doaSkid69]

Thanks for the video guys 1 question My car was tuned it's on SD and since it was tuned I have made some changes whilst rebuilding the car only crucial change is iv gone from a catchcan and pcv system and now iv fitted a 3port can and it's VTA and iv removed the pvc system all together, I'm aware of the drawbacks of VTA I'm just wondering if the tune will need a tweek atall based on the potential to have a different AF mixture with the iduction of crankcase gasses And now not having any reduction in fuel mixture quality with VTA will things be different? Il monitor with the wideband AFR anyway but curious what you think that's all 😌

[@FlatironsTuning]

Thanks for your question. Yes, typically switching from a closed catch-can/PCV system to a Vent to Atmosphere system does require a tune for the reasons you mention. I would definitely recommend monitoring your AFR's, and get the car tuned if you see anything that is unusual. Hope that helps and Stay Tuned!

[@doaSkid69]

@@FlatironsTuning Thanks for the reply... I think deep down I knew the answer as I was typing... But sometimes it's better to ask someone with more experience Plus secretly I was hoping to be wrong and you would say it's fine 😂😂 ok guess a session with the mapper is required 😋 Thanks 👍

[@lutherblissett9070]

What are your thoughts on blow-through MAF setups?

[@FlatironsTuning]

Thanks for your question. Before speed-density conversion was a possibility, that was a band-aid for high power cars. Now that Speed density conversion is doable, that is definitely the way to go. If you haven't watched it all ready, you should go through our MAF Vs. Speed Density video here: kzbin.info/www/bejne/rJzKo5RtndVse68 Thanks for watching and Stay Tuned!

[@420turbos]

Made some great power with a few dsm setups running different versions of the old maf translators. I miss those days. Indeed its day has passed though. Speed density benefits are worth the cost to convert if that's is the direction you want to go.

[@Pr0j3ctSTI]

Grimmspeed claims that their front mount Inter cooler does NOT require a tune. It says “No change in maximum boost or time to spool so it's safe to install and drive”. Can you give your opinion on that? Thanks in advance

[@FlatironsTuning]

Thanks for your question. With something like that, it is great for that claim to be made, but I'd say you would at a minimum want to datalog the car after install to make sure that your engine is running properly. Maybe it would be, or maybe it would just need a slight change to the calibration to get it where it needs to be. Far better to take a look at the logs that to hope that everything is okay. Thanks for watching and Stay Tuned!

[@santiagobernabeu7620]

Hu guys silly question here. A couple of years ago I had my short block on my 06 WRX rebuilt. There was no tune needed again because I was told it was the same engine. Move forward to present time and I need to buy a new complete engine. My question is if I buy a new complete engine OEM or say an IAG engine would this require a new tune or would just be fine in running my old tune since the engine would the same or even better if I went with an IAG engine. Thank you for your help.

[@FlatironsTuning]

Thanks for the great question. As long as you are keeping with the same parameters with the engine (ie. compression ratio) and you aren't changing your turbo, injectors, or any other critical components, you should be okay with the same tune. However, if you had a failure that could be at all Tune related, it would be a good idea to at least have the car checked by the Tuner once the new engine is in to make sure that it is running properly. Hope that helps and Stay Tuned!

[@impulseproman]

I think my mind need to stay tune

[@FlatironsTuning]

Ha! I feel you there. Thanks for watching and Stay Tuned!

[@dundizzle93]

When does it make sense to move from a MAF-based calibration to Speed-Density?

[@FlatironsTuning]

That is a great question. And we actually have an entire video on exactly that! Here is a link to that video and I hope it helps answer your question. kzbin.info/www/bejne/rJzKo5RtndVse68&feature=shares Thanks for watching and Stay Tuned!

[@gunhound45]

My stock turbo inlet tore and the only replacement I had was an AVO silicone inlet. It does not change anything before the MAF so the local tuner said it was fine, is this going to cause any issues or should I try and get a stock turbo inlet again?

[@FlatironsTuning]

Thanks for your question. Replacing the turbo inlet doesn't require a tune because, as you say, it doesn't change the calibration in any way as long as you are able to connect everything back to the inlet. Hope that helps and Stay Tuned!

[@gunhound45]

@@FlatironsTuning Is this the case even when the new inlet is larger/less restrictive? Or is it because the MAF has already measured that air, it doesn't matter if the path to the turbo is less restrictive?

[@qpl610]

Thanks for the video. I've had a K&N Typhoon intake on a 2005 STi running the stock tune for 13+years with no issues. Do you have any experience with this intake on Subarus? I'm content with the power so I've never tuned the car. Would you still recommend tuning in my situation? Something like an AP and an OTS map? Thanks.

[@FlatironsTuning]

Thanks for your question. With that much time on the intake, you are definitely fine with the stock mapping I'd say. Any issues would have come up long ago. Thanks for watching and Stay Tuned!

[@qpl610]

@@FlatironsTuning Makes sense. Thanks for the quick response. Keep up the good work :)

[@zippack999]

im Being told that an AOS needs to be tuned is this true

[@FlatironsTuning]

Thanks for your question. That is only true if you are switching from a contained AOS (Street Series) to a vent to atmosphere AOS. If you still keeping the PCV system connected as it was with just the AOS collecting the oil, you wouldn't need a tune. We discuss this specific question in another video here: kzbin.info/www/bejne/bJOzmKaipbydl80si=EK_sYGQ1uhIchwbh Hope that helps and Stay Tuned!

[@maliquenriquelique4152]

He never talked about aos and you don’t need a tune for it

[@FlatironsTuning]

Thanks for your question. We actually have a video talking about that specifically. Here is the link: kzbin.info/www/bejne/bJOzmKaipbydl80 Thanks for watching and Stay Tuned!

[@pottsmedia5492]

When you install a non-factory air freshener.

[@christhompson5739]

Soon cars will be like that one wheel scooter, unplug the battery or replace identical parts and it bricks.

[@FlatironsTuning]

Man, let's hope not. Thanks for watching and Stay Tuned!

[@kelvpoon]

Why is Subaru doing silly things like this and not the German way? That sounds like a better system?

[@kidi5988]

But when all the German cars last 100k miles and all the Japanese cars last 200k why wouldn't the germans do it the correct way like the Japanese

[@Quebecer_Powerstroke]

On a Subaru, changing the shift knob need to have your ECU tuned.

[@FlatironsTuning]

There is definitely that impression out there. Our goal here is to get some better information and criteria out there to help dispel that where applicable. Thanks for watching and Stay Tuned!

[@shawnpurtell1104]

Yea good luck getting a tune rip Cobb;(

[@honda56221]

That's not even close to true. What cobb is doing is basically just not letting tuners bypass emissions related equipment using the ap tuner software. Has nothing to do with tuning itself. But it does interfere with doing mods that change/ remove emissions because you will get a cel. But tuning is still alive and well.