Talk me into/out of a JB4 stack

scrllock

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Dec 17, 2018
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There isn't a requirement to reflash when running pump vs. E85 mixtures with the basic BEF implementation.

Like I said, "avoid talking about in direct terms," since you're using "mixtures" to qualify your statement, which is true, but not for mixtures above e40 or so.
 

Terry@BMS

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Jan 23, 2017
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Like I said, "avoid talking about in direct terms," since you're using "mixtures" to qualify your statement, which is true, but not for mixtures above e40 or so.

People run from E10 up to E85 with JB4 without the flex fuel sensor and MHD logic, have done for years...

There are some limitations, for example on E10 you wind up running a higher timing advance, lower boost profile, relative to what some of you prefer (high boost low timing advance), but the approach has proven to work well. Some custom tuners implemented other profiles/approaches for flex fuel changing mixtures before the new table blending including different load feedback and dynamic IAT spoofing for timing adjustments. But as I said above for the extra $99 or whatever the table blending is a good approach and we provide free maps for it.

Customers also find it convenient to have the speedo flash their E85 mixture every startup. :)
 

GreyNBlueE92

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Oct 3, 2018
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People run from E10 up to E85 with JB4 without the flex fuel sensor and MHD logic, have done for years...

There are some limitations, for example on E10 you wind up running a higher timing advance, lower boost profile, relative to what some of you prefer (high boost low timing advance), but the approach has proven to work well.

Is this only on map 5?
 

Terry@BMS

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Jan 23, 2017
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Map5 if you don't have a flex fuel sensor installed. If you have a flex fuel sensor then you use the WMI map with modified settings so boost profile is based on E85 mixture read from the sensor rather than meth flow.
 
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scrllock

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Dec 17, 2018
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People run from E10 up to E85 with JB4 without the flex fuel sensor and MHD logic, have done for years...

Customers also find it convenient to have the speedo flash their E85 mixture every startup. :)

That's some vague grammar. You're saying people run up to e85 without the sensor OR logic, or with your virtual flex fuel coupled with the mhd logic? Either way, doesn't sound ideal--though of course if you do have the mhd ff license, it's much cheaper to pay for the motiv kit than a jb4.
 

Tuppidsay

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Aug 3, 2017
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I've been using a JB4 since day one with my car. Its gone from jb4 and bef to jb4 bef and meth to jb4 bef and pi. After some initial duty bias tuning to really get good control of the waste gates, its great. meth worked fine. PI is fantastic, it just kinda works with very little tweaking. most of that tweaking is from my picky ass not that it needed it. I doubt i will ever remove it for another solution. only thing better for a setup that uses alternative/aux fueling is a stand alone thats fully integrated. As i understand it, once you add the bef, the jb4 only interacts with the wastegates.

The best thing is the integration. All controled through a bluetooth app. Yes, i know, MHD finally got their bluetooth adapter out in the wild. But any, addon systems, meth, pi, etc will have their own controls or apps etc. Everything works alone.

FBO eh I would just mhd
Aux fueling definately jb4
 
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Terry@BMS

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That's some vague grammar. You're saying people run up to e85 without the sensor OR logic, or with your virtual flex fuel coupled with the mhd logic? Either way, doesn't sound ideal--though of course if you do have the mhd ff license, it's much cheaper to pay for the motiv kit than a jb4.

People run up to straight E85 with the sensor and our E85 back end flash, prior to the new logic MHD added. Usually running full E85 at any reasonable power level requires port injection as well which the JB4 will also manage for you in an integrated format that is much better than what can be done with a stand alone PI controller. It integrates in with JB4 controlled anti-lag nicely as well. The extra safety provided with fuel pressure, trim variance, run lean, are unmatched with what can currently be done in a flash only environment. Not to mention cutting PI when DSC kicks in, when the clutch is pressed, etc, to keep you from blowing up your manifold.

As for cost the JB4 is pretty inexpensive and many people have one floating around anyway. When you combine the free mapping we provide, other things you won't need to buy for a flash only setup, and the future resale value, it's a great option. Like all tuning solutions no single solution is ideal for every situation but the JB4 is as close to a Swiss army knife as they come.
 

Schof1014

New Member
Apr 5, 2020
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People run up to straight E85 with the sensor and our E85 back end flash, prior to the new logic MHD added. Usually running full E85 at any reasonable power level requires port injection as well which the JB4 will also manage for you in an integrated format that is much better than what can be done with a stand alone PI controller. It integrates in with JB4 controlled anti-lag nicely as well. The extra safety provided with fuel pressure, trim variance, run lean, are unmatched with what can currently be done in a flash only environment. Not to mention cutting PI when DSC kicks in, when the clutch is pressed, etc, to keep you from blowing up your manifold.

As for cost the JB4 is pretty inexpensive and many people have one floating around anyway. When you combine the free mapping we provide, other things you won't need to buy for a flash only setup, and the future resale value, it's a great option. Like all tuning solutions no single solution is ideal for every situation but the JB4 is as close to a Swiss army knife as they come.
 

Saptap96

New Member
Nov 2, 2020
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Once you've done a "BEF" the JB4 isn't really doing much except adding a confusing layer into the mix. JB4 at that point is then useful for its other features such as steering wheel controls and meth control etc. If you're not using any of that stuff then not much point in spending extra on the JB4.

Your absolutely incorrect, I have BM3 stage 2 BEF with JB4 running map2, and it pulls way more harder than just with the BM3 flash.
 
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Saptap96

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Nov 2, 2020
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Once you've done a "BEF" the JB4 isn't really doing much except adding a confusing layer into the mix. JB4 at that point is then useful for its other features such as steering wheel controls and meth control etc. If you're not using any of that stuff then not much point in spending extra on the JB4.
Absolutely incorrect.
 
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scrllock

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Dec 17, 2018
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So the JB4 is somehow capable of adding more timing/boost than the ECU? All that says is they're willing to take more risks with your motor than a competent tuner would.
 

nyt

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Sep 15, 2019
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So the JB4 is somehow capable of adding more timing/boost than the ECU? All that says is they're willing to take more risks with your motor than a competent tuner would.

JB4 adds a number of safeties not present in the dme.
 

scrllock

Sergeant
Dec 17, 2018
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2011 335xi
The value of which is questionable, especially giving the relatively slow polling rate of the JB4 vs the DME itself. :rolleyes: But if you're going to be leaning motors out to "pull harder," I suppose that's something to try and sell.
 

nyt

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Sep 15, 2019
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The value of which is questionable, especially giving the relatively slow polling rate of the JB4 vs the DME itself. :rolleyes: But if you're going to be leaning motors out to "pull harder," I suppose that's something to try and sell.

You don't really seem to grasp how the JB4 functions.

AFR target is controlled by the DME.

JB4 polls plenty fast. The latest update I believe polls the canbus at 100hz. That's more than fast enough to determine lean conditions, mismatched trims between banks, overboost, fuel pressure drop, etc. You're not losing DME protections by using a JB4, you're gaining other protections.
 

scrllock

Sergeant
Dec 17, 2018
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I've talked to enough shops and tuners who've seen cars lean out with a piggyback to know that's nothing I'd ever push someone to put on their car.
The only significant safety they've added is limiting boost based on oil temp, but that's possible with custom tuning, and then you're not screwing with the DME's much faster safeties by telling it that boost/lambdas/trims are lower than they actually are (and then polling twice as slowly!)
 

nyt

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Sep 15, 2019
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I've talked to enough shops and tuners who've seen cars lean out with a piggyback to know that's nothing I'd ever push someone to put on their car.
The only significant safety they've added is limiting boost based on oil temp, but that's possible with custom tuning, and then you're not screwing with the DME's much faster safeties by telling it that boost/lambdas/trims are lower than they actually are (and then polling twice as slowly!)

Again, you really don't know how it works. You're speculating and taking misinformation as gospel. Also, ignoring all the other safeties I just listed, which isn't even a comprehensive list.