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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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@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 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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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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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.
 

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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.
 

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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.
 

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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.
 

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I see peak boost at 19.1 psi and tapering to 17 or so near redline.
 
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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.
 

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I used a TurboXS UTEC piggyback on my 2005 Legacy GT but then took it out and went with open source tuning with a tactrix cable and a laptop instead so I could be in full control of everything.

(not my image but looks exactly like mine)

 

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@Outbakkr what fuel and maps were you using for the first two logs?
 

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Is there any way to access knock info? I had a hard time understanding the timing I was seeing in your logs.
 

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If the first log was map 1 then it was overshooting the +3 psi target. Stock when I checked my car I got around 14.5 psi peak with rapid taper which matches the spec. It doesn't stay at 14.5 very long at all. +3 psi would be 17.5 psi peak but from the very first run it was around 19-20 psi peak, or about +5 psi?
 

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Would you be willing to run Map1 just for information sake?
 

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Sure, but it would be with 93 in the tank.
Thanks, yes I would like to see map 1 with 93 octane fuel, just for knowledge. In my area premium is 92. I wouldn't run Map 1 on 87.

Since it seems we can't see knock events with the jb4 in the OBD-II connector, can it be unplugged and a regular dongle used for more traditional logging, or would that undo the map in some way? I'm a little confused because it's not clear to me that you need the JB4 always plugged in there or not for it to work properly unless logging with it.
 

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If it works without the canbus connector then you can log using some other OBD-II dongle, right?
 
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I think their wording is insufficiently detailed. It's not clear if it helps the off the shelf tunes, or if they're talking about custom tuning. I suspect that an OTS tune is not affected by the OBD-II connector except for logging, but that logging is necessary to do a custom tune. JB4 says that if you remove the piggyback the car is stock, so I don't think it's programming your stock ECU at all, just intercepting and modifying data from the various engine management sensors and devices that it connects to.
 

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AFR 11.8 at 18.5 peak boost on Map 1 93 octane. When I did my own tunes I would be around 11:1
 
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