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DallasBoosted replied to the thread JB4 as boost controller only?.

"

Originally Posted by Terry@BMS

You need to wait for us to write single turbo boost control algorithms for the JB4 for it to work properly.

Right, I assumed this was the case. But you think its possible, then, to have the JB4 doing nothing but boost? I.e. fuel and timing are controlled completely by the DME and the JB4 isn't biasing any inputs besides the MAP sensor as we discussed (clamping MAP value at the DME's expected boost level)?

Related question: what happens when the JB4 clamps the MAP signal at some value lower than the actual value? Doesn't the DME put in less fuel than would be required? So the JB4 would bias the o2 sensors in that case to gain some extra enrichment to meet target AFR's etc? This is what I want to avoid; I want the DME seeing the unmolested signal in all cases. Any thoughts on this would be appreciated. "

Yesterday, 05:04 PM

DallasBoosted replied to the thread JB4 as boost controller only?.

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Originally Posted by Terry@BMS

Load 200 all across would be some sort of wacky boost curve between 16-20psi depending on RPM & air intake temperature. What the JB4 would do would depend entirely on what actual boost was doing vs. the DME target via whatever was controlling it.

Terry, thanks for answering my questions. You can see where I'm trying to get, JB4 controlling boost only and modifying the values going to the DME as little as humanly possible. How do I get to there from here? Using a product like the JB4 to overcome the most glaring flash-tune limitation so far (external wastegate control) seems like a great way to solve that problem. I just don't want to introduce more problems at the same time. See where I'm going? And it works out great for you at the same time, you sell JB4's.

Even if all their features aren't enabled...

Thanks "

Yesterday, 01:58 PM

DallasBoosted replied to the thread JB4 as boost controller only?.

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Originally Posted by Terry@BMS

If you go in and zero out the o2 bias & fp bias, zero out cps or don't install the wires, and remove the solenoid connections so it can't control boost, then the JB4 will report actual boost to the DME up until the factory boost target at which point the JB4 will clamp the boost signal at that level, unless actual boost goes over the JB4 target, in which case the JB4 will start to report higher than actual target back to the DME for throttle management. A few guys run the JB4 with an external controller but they just run a fixed boost level across the board and enter that value both in the JB4 and their external controller so boost hovers around the JB4 target. Sloppy but workable short term.

Generally speaking, for it to work right the JB4 needs to be controlling boost. Some day soon we'll offer that functionality. Until then I don't think there are any good options. The procede in theory is setup for external wategate control for FFTEC's kit but I don't know if that would work with another kit or whether or not they would share the firmware. You'd have to check with them.

If the DME set boost is slightly higher than the JB4 target (set load target at say, 200 across the board in the DME) then set the JB4 @ 18psi, then the DME would see the real value the entire time, and the JB4 would accurately control the boost @ 18psi without biasing or clamping any other values, right? And if it overboosted past 20psi, the DME would close throttle for safety just like its supposed to? "

Yesterday, 10:22 AM

DallasBoosted replied to the thread JB4 as boost controller only?.

" If the JB4 were used for boost only, would it bias the values the DME sees at all, or would the DME see everything as-is and the JB4 just controls the wastegate(s)? "

05-20-2013, 06:45 PM

DallasBoosted created the thread JB4 as boost controller only?.

" Terry, would it be possible to use the JB4 with no bias on any inputs/outputs, solely as a boost controller? And would it be further possible to use the Req. Boost values (or wgdc) from the DME to set the boost control point?

In this way, would it be possible to run external wastegates either on a single or twin turbo N54, because the DME is getting the boost it asks for; just not in the way it thinks? And the DME could handle fueling/timing completely through the flash via Cobb/whatever. Understanding in this scenario that you'd be sacrificing any of the map-switching and auto-tuning benefits of the JB4, and you'd have to re-flash to change boost settings. Essentially, the JB4 would be doing nothing but replacing the idiotic stock boost control system on external wastegate systems.

Is this a mode that could be programmed and sold by you on the JB4? "

05-20-2013, 05:27 PM

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