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BMS JB4 'Piggyback' Tune for the 2.4T Outback(s)

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After searching for available performance parts for the 2.4T, I learned that Burger Motorsports had the JB4 available for the ‘22+ WRX. I reached out and they replied that it would work with the 2.4T Outback as well. It is still in Beta format but I still went for it and placed my order. I received it on Monday and spent 1hr last night installing it. I opted for the Bluetooth module and purchased the app (personally, I think that they should include a one-time use code if you opt for the BT module add-on because it feels like they’re nickel & diming the customer to keep purchasing extras).
The install was straight forward and the online PDF/directions were pretty thorough (if you have some sort of mechanical competency). Identifying the plugs that are sandwiched was pretty easy. Pulling the HPFP plug was a pain and removing the front belly pan was the most labor intensive to get at the EWG plug at the Turbo. I rigged the OBDll plug and went out the door jamb because I couldn’t access firewall port last night (I will reroute it this weekend when I have time to pull more stuff apart..). After everything was installed and zip tied, I started it and connected the BT app and took it for a drive.
Now, on to the good stuff, and it is good. The JB4 is pretty simple in function; uses general operating parameters with data collected from motor via the module plugs & OBDll plug to override the factory mapping and controls the Electronic Waste Gate to hold boost longer rather than bleeding it (simplest explanation without getting too technical). I certainly feel the added power without a doubt. The drivability is absolutely normal and feels like stock in terms of the cars mannerisms while driving. The power comes on smooth and pulls harder all the way to redline. The CVT is totally unaffected by the additional power and drives and ‘shifts’ very similar to normal. In the end, it really is about a 40-50hp gain and is very suitable for the Outback considering the weight of the car, gearing and the fact that it IS NOT a WRX. I have only run Map2 which is for 93oct. I have ample access to E85 so I could run the E30/40 map too if I wanted and probably will just to test it out. My goal was to add a bit more power, which to me adds some confidence passing, entering a highway etc and for me, goal met. I have driven a true tuned cars for the past 15yrs (with the exception of my Gen5 3.6R) so I do feel that I have a very realistic expectation and understanding of tunes. In this case, I am onboard with the plug & play module vs a remapped ECU tune so that I can remove if/when needed and there’s also going to be a market to sell it down the road to the anyone driving the 2.4T if I decide I do not want it any longer. This option gives me what I think the car needs and I have zero concerns for the CVT handling the power, especially considering others will tow thousands of pounds regularly which will have much more strain on the CVT than adding 40ish more hp. On another note, it is still hot & humid here in the Tri-state area and the car will perform much better when the IAT’s drop with the change of the weather.
I will add some install pics this weekend when I have more time and continue to report progress with more usage. Feel free to ask questions and I will answer as best as I can. I also have ZERO affiliation with BMS and am just sharing information with the community for those that may be interested .

Cheers

Link to product page:
JB4 Tuner for 2022+ Subaru WRX BETA
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I reviewed the instructions, so it connects to:
  • Manifold Absolute Pressure (MAP) sensor
  • Mass Air Flow (MAF) sensor
  • Fuel Pressure sensor
  • Electronic Wastegate (EWG) Controller
The instructions seem to say that the OBD-II connection is optional - is it?
It seems that these are build-to-order - are the maps provided custom for the Outback specifically or is it generic 2.4 turbo maps?
Defaults to 91 octane map
The Bluetooth module is optional for use with the app.

If you don't have the Bluetooth module how would you change maps?

As I mentioned in another post about performance enhancement with our CVT cars - Cobb has hit a roadblock regarding the CVT in the 2.4 Outback (but not the 2.4 Ascent) and I'm not sure if hard-wiring to sensors overcomes this roadblock or if it's unrelated.

@Robert.Mauro there is a thread on the Ascent forum about tuning options and in it there's a post saying that someone contacted Burger about Subaru tuning and was told no. The situation has apparently changed and they now list these as compatible:

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I assume you are not concerned about your warranty. I suspect Subaru would find a way to deny any engine or trany problems.
 

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Discussion Starter · #5 · (Edited)
Yes, those are the connection points.

I do not know what the issues/weakpoints were with COBB and the CVT, but, as I have said a few times, its an Outback....What are the expectations? Are people looking to run 12's with them? Are they looking to surprise every more capable car that pulls alongside of them? Everyone has a different expectation. When you reflash the ECU, there is an visible imprint. Piggybacks, you have dig deeper into the ECU logs to search for irregularities so it is presumed safer to run should a user run into an failure issue. We all know, if you wanna play be prepared to pay...

As far as the OBDll plug, I am not sure. Since it is noted after mentioning the Bluetooth Module in the instructions, perhaps it is only part of the additional Bluetooth Module purchase.


I reviewed the instructions, so it connects to:
  • Manifold Absolute Pressure (MAP) sensor
  • Mass Air Flow (MAF) sensor
  • Fuel Pressure sensor
  • Electronic Wastegate (EWG) Controller
The instructions seem to say that the OBD-II connection is optional - is it?
It seems that these are build-to-order - are the maps provided custom for the Outback specifically or is it generic 2.4 turbo maps?
Defaults to 91 octane map
The Bluetooth module is optional for use with the app.

If you don't have the Bluetooth module how would you change maps?

As I mentioned in another post about performance enhancement with our CVT cars - Cobb has hit a roadblock regarding the CVT in the 2.4 Outback (but not the 2.4 Ascent) and I'm not sure if hard-wiring to sensors overcomes this roadblock or if it's unrelated.

@Robert.Mauro there is a thread on the Ascent forum about tuning options and in it there's a post saying that someone contacted Burger about Subaru tuning and was told no. The situation has apparently changed and they now list these as compatible:

View attachment 548649
 

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@Outbakkr you didn't mention whether it was mapped for the Outback XT specifically or if it was a generic 2.4 turbo map. Since you were in communication with them about the Outback specifically do you know?

Your caveat about pay to play is definitely appropriate here. You're testing a beta product and I commend you for taking the plunge and informing us about it. Someone has to be the first. Would caution others to not just jump on the bandwagon just yet unless you realize that you are putting things at risk (true of any mods not picking on this one) and some mods have greater risk than others. It would be a contribution if others were to buy it and let us know their experience with it, but I'm just worried about people who might not be thinking about the risk and just take a cavalier attitude.

I have modified a turbo subaru while under warranty before, open source tuned, increased boost, but manual transmission, and would have fully accepted paying out of pocket for resulting damage if it came to that.

I was an early adopter of the auto-stop eliminator which was somewhat of a risk as well, but as it turns out it's totally fine after 3 years in Outbacks. Also tested the Whiteline 20mm rear sway bar while under warranty, so I'm not just a blanket naysayer on these things - just advising caution. Engine and Transmission are kinda the most critical and expensive parts to repair and this device doesn't have a track record with Subarus yet.

Aftermarket tuned Subarus are known to have the following potential issues in general: Ring land failures, spun bearings - there are safe tunes and unsafe tunes and I don't think we know enough about this specific tune to declare it safe yet.

If you are able to monitor and log values with the bluetooth interface it would go a long way towards establishing how healthy the tune is. If adding an extra 50 horsepower and however many extra foot pounds of torque are put to use then it may be equivalent to severe service with regard to the CVT, where Subaru recommends 25k CVT fluid replacement. The WRX guys with CVT carefully monitored transmission temperatures and added extra CVT coolers to cope with the extra power.
 

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The FA24DIT engine has been proven pretty reliable (beefier rods that don’t bend like the FA20DIT and direct injection to prevent detonation from destroying ringlands like in the EJs). If you drive the CVT aggressively like in the WRX then I’d say monitoring temps is important. I’m just looking for extra juice when it comes to merging :) the outback is the family hauler with precious cargo
 

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The cooling effect of Direct injection is what allows an engine with 10.5:1 compression to run 14.5 pounds of peak boost on 87 octane - the EJ had much lower compression.

The FA20DIT is/was not without issues: 15+ WRX Motor failure roll call! - NASIOC

To be clear I'm not saying that this tune will damage your engine. I'm saying that we don't know how good this tune is yet.
 
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Yup datalog yourself to ascertain if the off the shelf tune is safe. Trust but verify. I’m asking my tuner who has tuned 3 of my cars to perfection whether he can do a Stage 1 + ETS intake protune with the JB4 on the Outback :) I think the power limit of the CVT is around 300whp based on the previous WRX generation. I’m just shooting for 280whp and calling it a day with either protune or OTS JB4 Map2.
 

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If you can, I'd like to know what their peak boost is and how it tapers - the stock tune tapers quite aggressively so peak boost is not held for long at all. Probably because it's tuned for 87.
 
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If @Outbakkr does enough testing/logging to establish confidence then possibly could there be a group buy? Many are chomping at the bit for the Cobb but that seems to be on the back burner and may never come to fruition.

Aside from CVT fluid temperature, boost levels, knock retard/ignition advance mutipllier knock stuff, what else should be logged? Do our cars have wideband O2 sensors? I presume BMS would also be interested in your logs.
 
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