JB4 owner since July 2018 and recently added BEF, the combo works very well and I highly recommend it.
Get the JB4 first, the power gain and features are amazing. I think the modding experience should be done somewhat slowly and in stages rather than all at once, the BEF just gives you something to look forward to down the line.
Go to the JB4Tech.com Forum ther's a whole thread about it but this is the jist of it
"We've got a pretty solid JB4 back end flash map developed now. Changes include revised air/fuel targets and scalar mapping for more consistent fueling, rescaling some annoyance limp mode limiters like turbine speed or boost too high, revised calculated torque for improved shifting, and of course bumping up ignition advance for more power. With the BEF loaded you continue to use the JB4 maps as normal for determining how aggressive you want to run, boost by gear changes, etc."
Go to the JB4Tech.com Forum ther's a whole thread about it but this is the jist of it
"We've got a pretty solid JB4 back end flash map developed now. Changes include revised air/fuel targets and scalar mapping for more consistent fueling, rescaling some annoyance limp mode limiters like turbine speed or boost too high, revised calculated torque for improved shifting, and of course bumping up ignition advance for more power. With the BEF loaded you continue to use the JB4 maps as normal for determining how aggressive you want to run, boost by gear changes, etc."
I have the BEF too, and I have my best 1/4 mile ET while using it. 11.71 @ 118.2MPH.
I feel it is smoother for DD as well as I have turned off the EWG option in the jb4 and have not had any overboost or funnies since.
Easiest way is because with a flash tune true (higher than factory) torque is cross stored in the stability control module. Remember the ECU is connected to every other computer in the car and lots of info is shared around and peaks are recorded for diagnostic purposes.
I have the BEF too, and I have my best 1/4 mile ET while using it. 11.71 @ 118.2MPH.
I feel it is smoother for DD as well as I have turned off the EWG option in the jb4 and have not had any overboost or funnies since.
So what is the purpose of purchasing another ECU? I only say this because I presume most people do it to "take it to the dealer" etc. If they can see regardless shouldn't you just keep your stock ECU and flash it? I'm only asking this because I'm not aware of any other reason or difference between flashing your stock ECU and purchasing another one to flash. Is there any benefit? Or just for safety/security reasons for example, if you brick your stock ECU you'd have nothing opposed to purchasing another one and having the stock just incase. Is that even a likely thing to happen?
Since you mentioned fuel octane I’m pretty sure you know what you’re doing.
If you’re limited with pump 93, there is absolutely no need to get the ECU tune. No matter it’s a full tune or a back end flash to pair with JB4. You almost have absolutely no room left for extra timing with boost level of map2, and the chance of your 93 can support map3 is minimal.
For a 93+E30 mix, 93+meth and higher octane, you can choose to run a full tune or a backend flash. You can start to get higher ignition timing. At this level of octane you probably able to milk your stock turbo dry, it’s reasonable to run more timing and less boost at this level of octane.
Since you mentioned fuel octane I’m pretty sure you know what you’re doing.
If you’re limited with pump 93, there is absolutely no need to get the ECU tune. No matter it’s a full tune or a back end flash to pair with JB4. You almost have absolutely no room left for extra timing with boost level of map2, and the chance of your 93 can support map3 is minimal.
That hurts. if thats true, why 93 BEF exists in the first place? They even make one for 91 octane. I quote from jb4tech.com:
RACE: Ignition advance set to around 17 degrees peak, AFR around 11.9:1 at peak HP, suggested for those running good quality 93 octane up through 30% E85. Typically cars that are not running CPI.
PUMP: Mild timing changes, AFR set to around 11.9:1, suitable for 91 octane and lower grade fuels (I'm looking at you Canadian 94) where timing corrections are an issue.
Cuz BEF can dial the fueling with the BEF without using the fuel wires. It can also run up to E40 without flipping a code which is priceless for people who mix E occasionally for fun. The other benefit people ignore is timing at shift. That 9deg shift timing can bring down 1/4 by 0.1-0.2s without adding any extra boost/timing.
Game has changed since BMS is selling their amazing TCU dirt cheap. The cost of getting EK1 device can be justified by the TCU itself so it's totally worthy to get a mild "pump" bef with TCU. Can't beat that price!
Do I need to always keep the BEF plugged into my OBDII port or once the flash is uploaded I can disconnect and put it in my glove box? I have an OBDII splitter but don’t know if it’s necessary.