Subaru Outback Forums banner

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

27886 507
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
21 - 40 of 508 Posts

· Registered
2022 OBW
Joined
·
244 Posts
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.
Absolutely - and also, here’s this:

Font Darkness Event Advertising Brand
 

· Premium Member
2021 Outback Limited XT
Joined
·
205 Posts
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.
I'd be more concerned about the CVT taking a dump as they seem to not like anything more than stock power. Which is why Cobb didn't do Stage2 and up tunes for CVT WRX's(last i knew), which I'm sure is why cobb stopped playing with a tune for the OBXT2.4. I'll be interested to see how the CVT will be holding up after 6mo, 1yr and beyond. 40-50hp may not sound like a lot but I'd think that CVT is sweating considering that's 70hp+ before parasitic loss
 

· Registered
Joined
·
225 Posts
Discussion Starter · #24 ·
A lot of speculation at this point regarding the potential effects on the CVT. We're on an Outback Forum, talking about Outbacks. I mean, I would think most would like a little more power at cruising speed to pass on a highway, enter a highway etc. I can't imagine many here going to AutoX or Drag Racing with their Outback (Wilderness especially).
 

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
Subaru has a way of interrogating the transmission control module (TCM) to determine if there was any chain slip and there is that TSB for the 2020 turbos to have their transmission logic updated, or replaced if there was chain slip. This tells me that the revised programming should prevent chain slip at least under certain conditions. Not sure if maximum torque handling per-se has been improved. Our CVT's have variable clamping pressure on the pulleys and the slip doesn't seem to be under full throttle as much as it is under partial throttle conditions. The engine computer tells the TCM what torque to expect and the pressure gets ramped up for it.

So the question isn't simply "can the transmission handle it" but is the ECU sending the right signals to the TCM to generate sufficient clamping force for the increased torque and is the transmission responding adequately.

Don't know if Cobb has bothered to look at the Outback CVT with the revised programming - it could be that the transmission can now handle more torque or at least experience less slipping if you have a TSB completed 2020 or a 2021 that came with the revised logic from the factory.
 

· Registered
2022 Outback Touring XT. Also 1995 BMW 525i with 240,000 miles
Joined
·
2,922 Posts
I assume you are not concerned about your warranty. I suspect Subaru would find a way to deny any engine or trany problems.
So Real deal being concerned over a warranty is funny?
 

· Registered
'20 Outback Onyx XT AGM/'04 Forester XT
Joined
·
561 Posts
Don't know if Cobb has bothered to look at the Outback CVT with the revised programming - it could be that the transmission can now handle more torque or at least experience less slipping if you have a TSB completed 2020 or a 2021 that came with the revised logic from the factory.
I wondered the same thing since it was a 2020 that Cobb tested on.
 

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
Cobb was able to do it with the Ascent TR690 (tows 5000 pounds) but not the Outback XT TR690. It's not "the CVT" there are differences even though both are TR690, both use the new Low Viscosity CVT fluid. The Base ascent has the same transmission but only tows 2000 pounds because it lacks a CVT fluid transmission cooler.

So again the devil is in the details. It's not just "CVT"

Not sure if the 2022+ CVT WRX uses the same CVT fluid as ours.

Again, not saying that the Burger device will induce CVT problems - just saying that it's not something to be "LOL" about. But if you buy the device and do logging it would help us all to have another set of data in addition to @Outbakkr

Even though the power gain is not super substantial one might consider going one step colder in the spark plugs as well.
 

· Registered
Joined
·
204 Posts
Between my 800whp STI with 175,000 miles (GR Hatch: - IAG Built| HTA86| >500whp| Daily driven...), my 4.5L GT4 ([4.5L GT4 review] Best sports car ever made? - Rennlist - Porsche Discussion Forums), and my E60 400whp 2019 WRX (NASIOC - View Single Post - 2015 WRX Dyno Thread), I’m all about finding the limits to cars. I don’t think one step colder plugs are needed because direct injection cools so well. I did one step colder on the EJ25 when I went stage 2 ages ago while I’ve had zero problems with my 2019 WRX with all the bolt ons :)

I’ll be happy to post my logs to benefit the community
 

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
Also for context not everyone has a stable of vehicles so that if one ends up with problems you have a bunch of alternatives at your disposal. If you have the means to push the limits of your vehicles and the consequences don't cramp your style that's wonderful. Not everyone's in that situation.
 

· Registered
Joined
·
225 Posts
Discussion Starter · #32 ·
Yes. Anyone feeling like this should just be happy with what they already have, or go out and buy a faster car from the factory. Its not a question of how many vehicles are in your garage, but rather your experience with modified cars and comfort level changing things from how the manufacturer designed them.

Also for context not everyone has a stable of vehicles so that if one ends up with problems you have a bunch of alternatives at your disposal. If you have the means to push the limits of your vehicles and the consequences don't cramp your style that's wonderful. Not everyone's in that situation.
 

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
The question isn't about whether or not to modify your car. The question is whether a particular beta device has a safe tune or not. That question hasn't been answered but hopefully your experience and @User1029 as early adopters can inform the community.
 

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
I see peak boost at 19.1 psi and tapering to 17 or so near redline.
 
  • Like
Reactions: CityHunter

· Premium Member
2020 Onyx
Joined
·
20,219 Posts
I was trying to figure it out by looking at the timing but I wasn't sure what I was seeing. The air fuel ratio looks maybe slightly lean at points at moderately high boost but because it's direct injection I don't know whether it's a concern. But at 20 psi I would consider running a cooler plug just in case, but I'm not sure we can find a one step colder plug.

OE is NGK SILKFR8A6 heat range 8 with .024" gap, so we would want SILKFR7A6 or equivalent if it existed.




I checked and we do have wideband O2 sensors, NGK 5-wire upstream NTK 27081 OE Identical AFR Sensor.
 

· Registered
Joined
·
204 Posts
JB4 is my first exposure to piggyback software and the lack of ability to monitor feedback knock, fine knock learn, and dynamic advance multipler does give me some pause. The tuner I use for my cars does not tune JB4 at the moment. I may decide to be patient and wait for Cobb to release their support for this car :)
 

· Registered
2022 OBW
Joined
·
244 Posts
JB4 is my first exposure to piggyback software and the lack of ability to monitor feedback knock, fine knock learn, and dynamic advance multipler does give me some pause. The tuner I use for my cars does not tune JB4 at the moment. I may decide to be patient and wait for Cobb to release their support for this car :)
With the “optional” OBDII connection I am curious if we could see everything you mentioned to include CVT, oil, and turbo temperatures.
 
21 - 40 of 508 Posts
Top