[Nadir Point]

Here's a good one for all the so-called diesel tuning experts out there:

"JBD (or any piggyback-type device, for that matter) effectiveness is severely compromised over time due to automated fueling adaptations performed by the DDE."

True or false?

I'm sure many related Q&A details will crop up if the thread progresses...

[135i_vs_]

Using JBd for 3 years, no loss in compromise at all.
If anything, the DDE should probably adapt to provide better performance with the JBd. JBd only alters the fuel pressure,which makes the DDE provide "more fuel".

[Hoooper]

There are differing opinions on this, some have seen an adaptation in their logging. I had one set to 100% for two years, my 1/4 time after I first put it on was nearly identical to when I went again a year later.

[BB_cuda]

DDE should not know of fuel rail pressure change. It is a resistor game only to fool the sensor. This is why doing a tune is better as the DDE can manage air and fuel in concert.

[DWR]

Originally Posted by UberArchetype

Here's a good one for all the so-called diesel tuning experts out there:

"JBD (or any piggyback-type device, for that matter) effectiveness is severely compromised over time due to automated fueling adaptations performed by the DDE."

True or false?

I'm sure many related Q&A details will crop up if the thread progresses...

Since you have parenthetically posed the question in an absolute sense, you have forced the answer to be false.

Are you essentially asking how the DDE can correct for fuel rail pressure manipulation?

[TDIwyse]

Originally Posted by DWR

Since you have parenthetically posed the question in an absolute sense, you have forced the answer to be false. Some piggybacks can be programmed so that adaptive strategies can be avoided. The JBD is not one of them. If you would like to know more about how the DDE can correct for rail pressure manipulation, just ask.

Well, the JBD can be manipulated to do this :-) But not by itself.

To the original question, it sure seemed to me that I saw mild adaptations occurring when using the JBD at high settings by itself, under certain circumstances. But it's difficult to have enough control over all the variables involved to know for certain. And if you read about the adaptation strategies used by the DDE, it would make sense that the DDE could adapt out the JBD distortion affects.

[DWR]

Originally Posted by BB_cuda

DDE should not know of fuel rail pressure change. It is a resistor game only to fool the sensor. This is why doing a tune is better as the DDE can manage air and fuel in concert.

Originally Posted by 135i_vs_

Using JBd for 3 years, no loss in compromise at all.
If anything, the DDE should probably adapt to provide better performance with the JBd. JBd only alters the fuel pressure,which makes the DDE provide "more fuel".

Since the DDE can measure that more fuel is being injected via the wideband O2 sensor, it can make temporary corrections and permanent adaptions. Because the fuel rail pressure will "look" correct (there are also adaptions for rail pressure but those aren't what we need to be concerned about) and the MAF will look correct, the adaption will be to the injector flow rate. Adaptions are a means to maintain good emission control. They are separated into operating regions. At high load and rpm, emissions are no more than a smoke limit. So, while the adaptions may not have as much effect on drag strip performance, they will affect part throttle and low load operation. A JBD initially feels peppy driving around town. Many report that they get used to it and it no longer feels as peppy - maybe it's really the DDE getting used to it

[BB_cuda]

Originally Posted by DWR

Since the DDE can measure that more fuel is being injected via the wideband O2 sensor, it can make temporary corrections and permanent adaptions.

I hadn't thought about the DDE figuring it out from other means. Thanks

[Hoooper]

I never felt that it was any less peppy driving around town. Its designed to have little if any impact on fueling at low boost, so impacts of driving around town would be very minimal to begin with. Add to that the car makes plenty of power stock to poke around in town and its unlikely there was ever any real gain in driving conditions that the DDE was adapting during anyway.

[Thecastle]

I have a JBD and it noticeably improved power. Especially at high RPMs, and never lost its extra steam. It is noticable when you remove it. Lots of folks have had them installed and did 1/4 mile runs and found no drop on peak performance. The JBD is designed to progressively distort fuel rail pressure. While the DDE may adapt somewhat to it due to 02 sensor reading, its only a potential issue under MAF/02 controlled fueling, this will not impact full throttle or high rpm fueling as these sensors are ignored.

It is the best bang for the buck power mod. There are better options like a full tune, for more power.

Ultimatly all tunes work the same way, mix more fuel and more air for more power. The details are a bit different, but essentially at its most basic level thats how you make more power on an ICE with fixed displacement.

[DWR]

Gents please understand I am not trying to dis the JBD. I agree it is a good bang for the buck.

My point was the JBD does adjust rail pressure within operating ranges that are under adaption. I'm not going to argue whether you can feel it in your butt.

[Thecastle]

Originally Posted by DWR

Gents please understand I am not trying to dis the JBD. I agree it is a good bang for the buck.

My point was the JBD does adjust rail pressure within operating ranges that are under adaption. I'm not going to argue whether you can feel it in your butt.

Maybe the dde does adapt under certain rpm ranges potentially. However adaptation to jbd has not been shown under full throttle conditions by folks doing 1/4 mile runs months apart. I could be wrong but basically other than some antidotal evidence no one has been able to measurable show jbd performance falls with time, at least at full throttle. http://www.e90post.com/forums/showpo...90&postcount=6

I've heard the adaptation theory before but haven't seen measurements of car performance to indicate this. As the link shows peak performance with the jbd dosent change.

[DWR]

Originally Posted by Thecastle

I have a JBD and it noticeably improved power. Especially at high RPMs, and never lost its extra steam. It is noticable when you remove it.

If there was adaption, it would be just as noticeable if you removed it.

Originally Posted by Thecastle

Lots of folks have had them installed and did 1/4 mile runs and found no drop on peak performance.

Lots of folks have installed them and could not run 100% initially, but by slowly increasing over time they eliminated limp mode. That's adaption.
I'm not a big fan of anecdotal evidence, so I'll hold myself responsible for starting us down that path - my bad.

Originally Posted by Thecastle

The JBD is designed to progressively distort fuel rail pressure.

Here's a JBD voltage transfer function that shows what is happening.

Originally Posted by Thecastle

While the DDE may adapt somewhat to it due to 02 sensor reading, its only a potential issue under MAF/02 controlled fueling, this will not impact full throttle or high rpm fueling as these sensors are ignored.

Not sure how you draw that conclusion. It would require that fuel injection flow rate adaption be "undone" under full throttle.

Originally Posted by Thecastle

Ultimatly all tunes work the same way, mix more fuel and more air for more power. The details are a bit different, but essentially at its most basic level thats how you make more power on an ICE with fixed displacement.

So, if adaption takes away fuel, then we would agree that power would be reduced. I guess we are just not agreeing that there is adaption.

[DWR]

Originally Posted by Thecastle

http://www.e90post.com/forums/showpo...90&postcount=6

I've heard the adaptation theory before but haven't seen measurements of car performance to indicate this. As the link shows peak performance with the jbd dosent change.

Thank you for that. It helps me understand your point of view.
The link shows 2 data points for ET. People run different ETs in the same day.
Can we see MPH data? That would be better.

[Hoooper]

The mph was higher in the later pass, it was something like 106.8 and 107.7. Different days different DAs

[TDIwyse]

http://www.micro-tronik.com/learning...ctronics-dde7/

Adaptation of rail-pressure regulating valve
For better rail pressure control, the characteristic curve of the rail-pressure regulating valve is adapted.



Mean quantity adaptation
An oxygen sensor is required for the quantity mean value adaptation function. This sensor is fitted after the turbine of the exhaust turbocharger. The oxygen sensor is a wide-band sensor that provides exact lambda values over a wide measuring range. The quantity mean value adaptation is a learning procedure in which the fuel-air ratio (lambda value) is correctly adjusted by adapting the air mass or exhaust gas recirculation rate.
This procedure does not affect the individual injectors.
The lambda value measured by the oxygen sensor and the air mass measured by the HFM are used to determine a mean fuel injection rate across all cylinders. This value is compared with the injection quantity specified by the DDE control module. If there is a deviation, the air mass is adapted to the actual fuel injection rate by adjusting the exhaust gas recirculation valve in such a way that the correct lambda value is set.
The MMA is not a rapid control operation, rather an adaptive learning procedure. That means that the fuel injection rate fault is learned in an adaptive characteristic map that is saved permanently in the DDE control module.
Application
The service function (quantity mean value adaptation) must be run if one of the following components was replaced:
· Mass air flow sensor
· Rail pressure sensor

[Hoooper]

I think were all in agreement that the rail sensor is capable of adaptation, the question is really whether it adapts in the range where the JBD is intended to be useful, under high boost and heavy fueling. My experience and lack of dropping track times suggests there is no adaptation during racing type conditions. Whether it adapts under normal driving conditions is kind of pointless. Who cares if your normal acceleration pedal position gives you 40 or 45 hp? Youre still just accelerating normally to a given speed, if the JBD were to make it faster under that scenario and the car didnt adapt we as drivers would adapt and apply less pedal.

[TDIwyse]

Originally Posted by Hoooper

I think were all in agreement that the rail sensor is capable of adaptation, the question is really whether it adapts in the range where the JBD is intended to be useful, under high boost and heavy fueling. My experience and lack of dropping track times suggests there is no adaptation during racing type conditions. Whether it adapts under normal driving conditions is kind of pointless. Who cares if your normal acceleration pedal position gives you 40 or 45 hp? Youre still just accelerating normally to a given speed, if the JBD were to make it faster under that scenario and the car didnt adapt we as drivers would adapt and apply less pedal.

My experience was a bit different than yours. Although, as I mentioned earlier, it's difficult to control all the variables in such a complex interdependent scenario, especially since some of the adaptations require learning and time to achieve.

Comparing track, or dyno results, is also fraught with difficulties. Dyno's try to correct for ambient conditions, but there's various correction methods that can be used which don't even agree with each other (DIN vs SAE vs ISO vs ...), and one car may not react to changing ambient conditions like another one. The track can be even worse, as changing ambient conditions are not accounted for (unless you apply standard corrections for Density Altitude), but then you also need to consider wind variations. And also things like your overall weight, the fuel in your tank (same BTU's or Cetane or etc.), the condition and pressure of your tires which affect rolling resistance, is the alignment the same, is your air/fuel filter the same obstruction, is your DPF (assuming you still have that) at the same loading condition as the previous test so your exhaust back pressure was the same, etc....

Just really, really difficult to control all those things.

Some things I had looked at were the rail pressure vs injector opening times vs how much fuel the DDE thought was being injected under full fueling conditions and how Gtech (was using Gtech back then before going to PerfExpert) data behaved over time with the JBD set at "high", vs how things behaved with keeping JBD at "low" and periodically applying the in-cab switch that would turn the setting back to "high".

The results convinced me that it was better to drive around normally with it "low", and throw the switch for "high" when I wanted it. Driving around in "high" all the time was still much better than stock, but not as good as going from "low" driving most of the time to "high" for limited use.

But your car may behave differently than mine.

[DWR]

I've reread the original question and want to change my answer and respectful acknowledge Hooper's point (and any others in that camp).
Is effectiveness severely compromised over time? No, not severly.

Just to add some detail to TDIwyse's post. The zero fuel adaptions are to the pilot injections only. Those pilot injections are in play up to 3,800 rpm. However, they are a minority portion of the total injected volume.

Gentlemen, thanks for the vigorous discussion. Ultimately, I agree with the experiences you a have related. That as a matter of degree, the JBD remains an effective performance enhancement over time.

One final thought. Not everyone wants to go TDIwyse fast, but if you do, every single digit HP enhancement counts. That's my orientation too. It makes you think about things differently and sometimes that does not match up with how the rest of the world sees things. Sometimes I forget that. Cheers.

[temporaptor]

Seems like it may adapt to add in more ERG useage, adding to more CBU build up......

[Chief Orman]

Time to get my tune from Jarek squared away.

[Jay Carnes]

Originally Posted by Hoooper

I think were all in agreement that the rail sensor is capable of adaptation, the question is really whether it adapts in the range where the JBD is intended to be useful, under high boost and heavy fueling. My experience and lack of dropping track times suggests there is no adaptation during racing type conditions. Whether it adapts under normal driving conditions is kind of pointless. Who cares if your normal acceleration pedal position gives you 40 or 45 hp? Youre still just accelerating normally to a given speed, if the JBD were to make it faster under that scenario and the car didnt adapt we as drivers would adapt and apply less pedal.

Sorry, all I say to myself when I see your username.