[Ozzie335i]

I have an N55 with Pure 2, PI, and all of the proper supporting hardware.

For guys that have port injection and have first gone with a JB4 port injection BEF and JB4 PI Controller, then ditched the JB4 and gone with a flash type PI tune and flash PI Controller. Is the flash tune smoother. better, safer...? Comments welcome as I am at a crossroads with this. May go all out MHD.

For the guy that needs to set me straight and tell me to ask it on the N55 side of the house, thanks, but no thanks. I feel that I'd more likely find someone here that has done this, and can comment on the results.

[dyezak]

The question you are asking is more complex than you might think. First off you asked in the N54 section, so you're going to get an N54 response. But be warned, before reading this...the flash capabilities between the N54 and N55 aren't the same and I am not familiar with the N55 flash limitations.

From an N54 perspective the real issue with PI is safety. When the DME senses a misfire it cuts fuel to that cylinder. The fuel cut is accomplished via disabling the DI injector. The problem with PI is that it is being triggered by boost and RPM. This is the same for flash or for JB4. It (the PI system) has no clue a misfire occurred and the DI injector is disabled. What you have in this instance is a situation where more than 1/2 the expected fuel in this problematic cylinder has just been removed, yielding a dangerously lean environment.

Now what happens if you get pre-ignition (i.e. detonation)? Kaboom is right. You'll be in an extremely lean environment during that pre-ignition and will experience extremely high in cylinder temps and pressures that could melt or crack a ringland...which could also bend a rod due to the pressure spike.

Most people don't try and "power through" misfires so bad the DME is cutting fuel, but if you did this is the situation you'd find yourself in.

With all that said which is better, flash only or JB4? It's effectively a tossup. Terry has said he could update the firmware to detect the misfire code via CAN and have it trigger the PI to stop, but as of yet that feature doesn't exist. So while the JB4's safety systems are always one of its top selling points this particular safety hasn't been coded and released yet.

So it really doesn't matter. But, all that's from an N54 perspective. I'm not sure if there are flash only limitations in the N55 world that would drive you to the JB4 instead.

ETA: I've had 3 N54's and have used COBB, Procede, JB4 and MHD and done combo's with BEF's and Piggy backs. Each have their selling points, and their drawbacks.

[Ozzie335i]

My current setup uses JB4 and MHD, with a custom BEF made by MHD. Am considering going with flash as I have read that it has smoother power delivery. Thank you for the write-up dyezak. Great info.

[bbnks2]

Originally Posted by Ozzie335i

My current setup uses JB4 and MHD, with a custom BEF made by MHD. Am considering going with flash as I have read that it has smoother power delivery. Thank you for the write-up dyezak. Great info.

wow I can't believe how messed up this community is because of BMSs' made up words.

A "BEF" is a flash tune and there is no such thing as a "flash tune made by MHD." MHD is just an app used to load a file onto the cars computer. Wedge Tuning wrote the N54 off-the-shelf tunes that are sold through the MHD app and BMS wrote the off-the-shelf tunes (BACK END FLASHES) that are written specifically for use with JB4 and are free for use on N54tech.

The problem is, neither of these options are "custom." They are simply generic tunes that are meant to work on all cars. Therefore, a "custom" tune written specifically for your car and mods is generally "smoother." Even a generic tune (or "BEF") will be massively smoother than a JB4 only setup.

You use JB4 to control your port injection which is the only reason why a "custom" flash tune for your car would be referred to as a "back-end-flash." BMS just made up some stupid acronym so the masses wouldn't realize that the JB4 piggy back device has limitations to what it can "tune" once you start getting more aggressive with it. If you already have a custom "BEF," [a flash tune written specifically for your car] there won't be any "gains" by eliminating the JB4 device from your setup.

Your question should read "Is there any advantage to ditching JB4 as a port injection controller and using something else?" I personally would say yes because people have had tons of problems with the JB4 firmware. The hardware itself is failure prone and so is Terry's programming. The efforts made by BMS are noble, and lots of hard work goes into making JB4 work. I don't mean to take away from that, but the project itself has ballooned into something way more than what is really should be.

[Mike@N54Tuning.com]

There is just so much more you can do with a JB4 in the mix not just relating to PI. If money is no object best bet is to have the JB4 setup and then have a custom flash tuner custom tune your back and flash and boost targets as needed.

From the JB4 PI FAQ:

What is the difference between the SplitSecond AIC6 as a stand alone
and the JB4 PI controller?

The AIC6 is a simple stand alone system that allows mapping of port
injection as a function of boost pressure and engine speed.

The JB4 port injection controller is fully integrated solution
allowing enhanced port injection mapping and safety.

For example the JB4 port injection controller:

1) Uses low fuel pressure in conjunction with boost pressure to
evaluate injection pressure and adjust PI IPW dynamically as required
to maintain consistent flow volume. This becomes particularly
important in applications that are the edge of their low fuel pressure
supply. As low pressure drops or oscillates port injection IPW must be
dynamically adjusted to avoid run lean conditions.
2) Monitors pedal input, clutch input, gear, throttle position, etc,
allowing more advanced mapping and instant cut of PI when letting off
the gas or when traction control kicks in to avoid backfires.
3) Monitors current through the injectors and sends a signal back to
the JB4 altering it of various problems including a clogged or
disconnected injector, blown electrical fuse, loose ground, etc.
4) Monitors fuel trims in each bank and failsafes in the event of a
mismatch of more than 15% indicating a potential boost single cylinder
boost leak or injector flow issue.
5) Allows easy user adjustment of overall fuel volume using linear
"Fuel Bias 0-100" values by RPM, greatly reducing the typical mapping
complications when making manual tuning changes.
6) Integrates in to the JB4 multi-map system which produces on the fly
PI mapping changes when you change maps, when boost is reduced in
lower gears, or during anti-lag engagement.
7) When equipped with a JB4 integrated flex fuel sensor can
automatically adjust port injection volume based on E85 mixture
allowing for easy mixture changes.
8) Enhanced mapping logic such as tip in supplement to boost port
injection during sudden transitions like spool up or gear changes
where the high pressure pump tends to have problems keeping up.
9) Does not require a separate interface and cable for mapping and
tuning port injection. It's all done right through the JB4 interface
and logs greatly simplifying the process.

And from the JB4 BEF FAQ:

What are the benefits of running a JB4 with a flash rather than flash
only for tuning?

While it's possible to tune an N54 without a JB4 doing so comes with
many disadvantages.

1) The JB4 includes more robust safety systems than are possible via
flash only. Starting with fundamental safety systems like reverting to
a safety map if boost exceeds your safety setting, if the air/fuel
ratio in either bank turns dangerously lean, or if fuel pressure drops
below a safe level. While you might think the DME alone can handle
these basic safety systems surprisingly it's not the case. The DME
will happily let you run along at full power and a 18:1 AFR, with
boost pegged if a WG line drops off, and the only fuel pressure safety
provided is when fuel pressure drops down so low fuel injection itself
has to be suspended. In addition to these basic safety systems the JB4
offers layered advanced safety systems. For example it monitors fuel
trims bank to bank and reverts to safety if they exceed more than a
15% variance indicating a possible fuel distribution or o2 sensor
issue. Port injection and WMI add extra failure points and the JB4
control provides advanced safety systems for them as well. The port
injection FAQ covers the basics.

2) The JB4 boost control system is programmed as absolute meaning
you'll always target a specific boost level. Unlike the DME which
naturally implements a LOAD control system where boost levels go down
when it's cold and go up when its warm. The opposite of what you
generally want for turbocharged performance. In addition the JB4 is
quick and easily adaptable to a wide range of setups eliminating the
need for expensive custom boost tuning and the risks that come with
repeated logs on systems that are not yet setup. It's not uncommon for
engine damage to occur while a new setup is initially being dialed in.
The JB4 automatically tunes wastegate dutycycle, fuel trims, and other
important tuning criteria full time in the background greatly
simplifying the tuning process. In addition the JB4 auto-tuning map
can self tune for various ethanol mixtures without the need of an
expensive and difficult to install flex fuel sensor. Pedal to boost
mapping, spool aggression, boost by gear, and other critical factors
can be easily adjusted in dash on the fly to suit the needs for the
particular track or racing situation.

3) On the fly changes. Whether it's changing the boost/power level,
boost by gear setting (including being able to disable it on the fly
for burn outs or if traction turns out to be better than expected),
pedal input, 2STEP RPM, or what gauges are shown in dash, the JB4
allows a wide range of user adjustment real time from the drivers seat
without having to use a 3rd party device or risk programming the DME
between runs. You're able to make the changes while out on the track
where you need to make them.

4) The JB4 allows for much better real time feedback to the driver.
User adjustable in dash gauges allow you to keep a constant eye on
boost, timing, knock, meth flow, and/or AFR, all selectable and
changeable on the fly from the drivers seat. A user adjustable shift
light can be triggered making rowing through the gears easier. JB4
Mobile allows wireless bluetooth logging via your Android or Apple
phone without a cable locked in your OBDII port. In addition you can
select map0 on the fly to allow OBDII port logging and diagnostics
when needed for vehicle service. The JB4 default logging set includes
all relevant data required for tuning including boost, timing
cylinders 1-6, AFR and fuel trims in both banks, high and low fuel
pressure, load, calculated torque, trans temperature, and many other
parameters. The JB4 provides a simple to use but incredibly robust
data logging system eliminating the need to select what parameters to
record before each run and providing instant on the fly charting
without the need of 3rd party internet programs. We routinely add
parameters to the JB4 logging set based on customer feedback and
evolving tuning requirements. The JB4 samples boost and analog sensors
250 times per second and CANbus specific data like air, fuel ratio,
fuel trims, and timing advance 10 times per second.

5) Integrated JB4 features such as no lift shift, 2step, anti-lag,
port injection control, flex fuel sensor, and progressive water/meth
(WMI) control eliminate the need for independent add on boxes that are
more difficult to install and technically unable to communicate with
each other. Integration allows these extra features to share
information for a smooth and cohesive tuning solution. For example
with the JB4 NLS and JB4 port injection control when you press the
clutch in for NLS your port injection flow is momentarily suspended to
avoid huge backfires that have been known to blow out o2 sensors and
in extreme cases blow up intake manifolds. When the DME requests a
torque drop due to traction or stability control the JB4, WMI, and PI
systems all respond accordingly. JB4 anti-lag has a dedicated user
adjustable boost limiter to avoid unnecessary engine stress while
engaged. WMI integration is able to hold boost levels low UNTIL fluid
is flowing adequately to prevent spool up and transitional knock,
adjust your boost target if the fluid being injected turns out not to
be as potent as was expected or required to prevent knock, and in the
event of a fail-safe depending on the severity of the situation either
lower your boost target partially OR instantly dump boost out the
diverters/close the throttle/cut timing. These are just some of the
many examples of why having add on boxes an features all integrated
through a single system is advantageous.

6) The JB4 is widely used and widely supported including free unlocked
back end flash maps and custom mapping support from BMS via the
n54tech support forum. BMS sponsors and attends several 1/4 mile and
1/2 mile races per year continuously improving the JB4 base maps and
features based on real world experience and feedback. These updates
are provided free of charge to JB4 customers via n54tech firmware
posts.

7) The JB4 hardware is robust, reliable, highly developed, and
upgradable, with many thousands of systems in use since 2008 when it
was first released. The key to the JB4’s success is that it DOES NOT
replace the factory engine computer or DME. The JB4 simply adds on to
functionality already provided by the DME. As a result the DME remains
in full control of your engine at all times with the JB4 dynamically
making small but impactful adjustments to add in extra safety systems
and features and dramatically improve performance.