[torqueisking]

Thought this may be of interest to some. Make your own JBD with a $25 Arduino Uno!

With different power level settings, the JBD (at 100%) output (blue curve) changes only above 2.5Vin (X-axis). Vout is on the Y-axis.

[iaknown]

Interesting info...I always wondered if this was possible with an Arduino.

[DWR]

torqueisking, I don't know if you are a mind reader or a friend nearby sent a message, but I was looking for this just recently. Thank you so much!

First hint to all you would be programmers. Many have noted that the DDE starts to 'learn' around the JDB. This is part of the adaption strategy. Higher fuel pressure obviously adds more fuel for the same injection duration. At low to mid rpms the DDE sees this in O2 sensor input as an offset that requires correction. To avoid that, DO NOT initiate any rail pressure sensor adjustments below 3,000 rpm. That appears to be one of the limits of the adaption range.

Second hint, you may want to use Testo to monitor the Volume Control Valve duty cycle, if you want to avoid Limp Mode.

Happy experimenting ...

[torqueisking]

I wonder if the adaption is real or people are becoming accustomed to the extra torque. Have you heard of any real confirmation via logs or time slips?

I would think JBD tested for this and decided to not significantly alter the fuel pressure below 2.5V . That 0.25-0.3V reduction under 2.5V may be below the adaption threshold.

The adaption theory intuitively makes sense but perhaps the DDE runs open loop at WOT, X boost and/or Y RPM. I'll confirm this hypothesis ASATA or perhaps others who know the answer can chime in.

I also measured the JBD Vout at difference sweep speeds expecting to see changes in the curves as a function of dVin/dT (FP rate of change wrt time) . I suspect transient manipulation of the FP signal could result in more power without throwing a code. To be confirmed...

[DWR]

Originally Posted by torqueisking

I wonder if the adaption is real or people are becoming accustomed to the extra torque. Have you heard of any real confirmation via logs or time slips?

Adaption is an inherent part of ALL modern ECU control strategies. I was programming ECUs in the late 90s and was aware of it then. You are correct, there are trigger levels for many forms of adaption. The DDE uses the fuel pressure as part of the injection quantity (IQ) calculation. Any adjustment of pressure will effect the amount of fuel. The DDE uses the combinaton of MAF, O2 sensor and IQ to adjust calibrations. For more information on this please see page 87 in the attached document.

[Hoooper]

I ran a 12.9 with JBD right after the install, then ran a 12.8 at least 6 months later without ever having removed the JBD and with it at 100%. It doesn't seem to have adapted around it.

[DWR]

Originally Posted by Hoooper

I ran a 12.9 with JBD right after the install, then ran a 12.8 at least 6 months later without ever having removed the JBD and with it at 100%. It doesn't seem to have adapted around it.

Hooper, glad it is working for you. You did not give your trap speeds. Not sure if you are measuring traction or horsepower?

[Hoooper]

The first was 106.x mph and the second was 107.x

[DWR]

Originally Posted by Hoooper

The first was 106.x mph and the second was 107.x

Hmm, any idea where the additional 10 Hp came from? Methanol injection? Winter versus Summer blend? Maybe there was an adaption!

[Hoooper]

Less cbu I think. Methanol was the same between the two runs. The other option would be a difference in head wind, this track can be really windy at times and it's unlikely that the wind was the same between the two runs

[TDIwyse]

Hooper, that's interesting. I could actually see the "Fuel Rate" being modified after driving with the JBD at high settings if doing more than a few full fueling runs through the gears. Part of the reason I originally modified the JBD to allow in-cab manual adjustments, and then went to doing the progressive rail distortion ~2-3 yrs ago above the 3000 rpm point. Plus it put less stress on the drivetrain by keeping the torque in check at lower rpm's ...

[Hoooper]

Interesting indeed. I wonder if it applies adaptations to the whole curve that are only based on low pressure feedback. Since most of my time is highway cruising it would have plenty of time to relearn non modified rail pressure. If it learns the JBD at any point I can't imagine why it would unlearn it.

[DWR]

Originally Posted by Hoooper

Interesting indeed. I wonder if it applies adaptations to the whole curve that are only based on low pressure feedback. Since most of my time is highway cruising it would have plenty of time to relearn non modified rail pressure. If it learns the JBD at any point I can't imagine why it would unlearn it.

Let me try to add some clarity. The DDE tries to fine tune injection based on feedback from specific sampling ranges. None of those ranges are in high load high rpm regions. Therefore the adaption is extrapolated into those regions.

Hooper your thoughts are right on the money. So let's take this even futher. What if we can make the DDE learn to overcompensate with addition fuel? Essentially, what is the potential for DDE self 'remapping'? My investigations indicate it maybe as high as 8%.