WRS, you are obviously well educated in the field of signal processing. It took me two tries to pass that particular class so I'm not going to chime in at all from a technical perspective, lol. I will say this instead. Being able to accurately describe the complex inner workings of one specific box amongst a network of thousands of other different boxes doesn't necessarily make you a subject matter expert on the system as a whole. That's my perspective from 30,000 feet.

As a working electrical engineer I will tell you that when I have an idea, the first thing I do is go talk to my technicians. They know the system, I know the box.

Cheers,
Patrick

 

I have the FVD piggyback and so far, no one on the 991 turbo forum has admitted to owning it but I think emre uses it, he just hasn't acknowledged my queries.

 

Depends on the subject matter we are discussing. I have no specific knowledge of any of these boxes. I am basing my comments on the behaviors I can actually measure which are a result of using my Vbox to run acceleration tests before and after I make a mod. I don't have a system that can be attached to the OBDII port for measuring all the interesting parameters during a run but that would be a next step if I were to investigate further.

For now, I am satisfied with the results I got from the FVD module and bolt ons. I originally replied directly to the OP on his question and was told I was 100% incorrect which was simply not true. My tech told me that there was no way the plenum could be de-tuned by the ECU. I consult my techs too .

BTW, fyi, I have spent time consulting out at White Sands at a site run by both the blue suits and spooks, beyond that I can't talk but if you want to guess about my bona-fides regarding signal processing you should inquire what goes on out there where those two outfits coincide.

 

Nobody doubts that you are getting results with your module. We are also generally of the qualified opinion that it is not the best way to do it in terms of system health. You can unclog a toilet with a claymore mine and get measurable results. Regardless, it isn't in the best interest of the toilet.

Cheers,
- Patrick

 

Yeah but that has nothing to do with the FVD piggyback nor am I aware it has any ill-effect on system health that would not be more likely as a result of a flash tune.

 

Slightly OT, but related -

Does the stock ECU make modifications to account for a more free-flowing exhaust? Do power gains disappear as the ECU makes adjustments to account for the exhaust?

 

A more free flowing exhaust always helps. The programming in these cars relies pretty heavily on EGT measurements to keep the turbos working within safe parameters. Having a freer flowing exhaust will reduce back-pressure and heat generated by the VTG turbos, allowing them to spool much more easily, lowering EGT's, and actually allowing the ECU to provide not only better performance, but definitely more consistent performance too.

 

Tom ... I'm not sure you answered the question the PP asked regarding the "stock ECU learning and detuning the car" that is piggy-back tuned. And, that was my original question when I started this tread.


As I remember from a previous post, you wrote that piggy-back tunes will not hold. That the ECU 'learns' and removes the tune.


I am certainly not an expert regarding any of this ... but, I think you are incorrect if you say the car will revert to OEM system standards after hooking up piggy-back modules.


I've spoken with the German developers of FVDs piggy-back system and they categorically reject the idea that the ECU will eventually over ride their changes.

 

All I can tell you is our experience. And our experience shows that the ECU eventually compensates for the adjustments made by piggyback units. It's clear as day when we look at the programming inside the ECU with one of the units installed after some time. Now, the only variable is how long it will take. Does it happen in a few days? A few weeks? Longer? That's the only thing that's unclear. Does the ECU "de-tune" or "remove the tune" altogether...no not exactly. It can't because it's not technically a tune (in the traditional sense). The ECU simply makes adjustments to counteract something that it thinks is "wrong" with the car because of the altered input signals from the box.

Now I know every single company that sells a piggyback unit will tell you that I'm lying and that it's not true. Same with users who have the units installed on their cars. So to all those people I have a question.....

If they're sure exactly how the factory ECU works, then why don't they tune directly into it instead of using a piggyback box?

 

What data do you have to support your conjecture. If my car consistently continues to run better quarter times with the FVD module then I have to conclude that it isn't de-tuned. I think you should back up your claim with factual data that would help us in assessing your point. Your question is a canard.

 

The data that we have is something I'm not going to share with the forums, and you'll just have to accept that unfortunately. We collect the data of how the OEM programming in the ECU behaves using proprietary data-logging and tuning software that takes GIAC engineers years to develop. Sharing that information would mean basically opening the doors to how GIAC is able to OBDII port tune these cars while everyone else has given up or opted for piggyback units.

Also, please understand that I never used the words "de-tuned". What I said was that in cases where a piggyback is used, the ECU and the multiple other control units that are constantly measuring vehicle parameters will compensate for operating conditions which exist outside of the factory programming, the factory programming which is STILL running the car, even with the altered signals in place. Does that happen right away? Sometimes not. Luckily, you don't have to take my word for it, as there have been many cases lately of people going the "tuning box" route who are unfortunately unhappy with the results...many of who have even decided to remove the boxes altogether.

I'm extremely happy that your car is still running strong, honestly. Believe me, nothing bums me out more then someone who spends their hard earned money on a part that doesn't deliver. And quite frankly, your suggestion that I'm merely spreading a rumor is a bit insulting. You, and anyone else, can choose to believe what I'm saying or you can choose not to...that's why there are dozens of options for tuning out there. I've been on this forum for over 5 years and in that time have never spread false information. I pride myself on helping out the community....MANY of which are not even customers of our company.

 

WRS,

I think Tom is saying that if you looked at trim values in an ECU that has had a piggy installed, you will see that they are maxed out as the ECU attempts to renormalize the power output. Eventually, the ECU can't trim the anymore because it is operating on the extremes of it's corrective ability. I believe, and correct me if I'm wrong (Tom) that this is the "de tuning" that is referred to. The power may not return to stock but the ECU is constantly fighting to get it there and some power loss is to be expected.

This is an inherent limitation with piggyback boxes. Since the original factory code is still running at the core of the system, it is in a constant state of flux trying to get the system back to what it is coded to believe is "normal." A better way is to rewrite the code so that there is a different expectation of "normal."

- Patrick

 

See, this isn't what I am asking at all. I am asking you if you have data sets for cars that have been tuned with for example the FVD module I have and that demonstrated a loss of power over time after the initial installation. Frankly, if the ECU software is capable of a limited adaptation, unhooking the box for a week or two may easily fix that.

The OP used de-tuned so I just carried on with that to further the discussion. The factory programming never quits running the car and the FVD box never changes that, it simply responds to the things it measures, which happen to be many of the things the factory software measures. However, the FVD box sees everything first and can alter what the factory software sees.

The problem you have with your conjecture/claim is that as long as what FVD presents to the factory software is within the specified limits, the factory software has no way to know that there has been a modification of the sensor data. The FVD engineers are very likely able to make the same measurements as the guys at GIAC do and form their own conclusions about the response of the ECU to various different sensor inputs under various loading conditions. I believe this is the purpose of using dynos and tracking the cars with data logging. They are not ignorant ***** that have just arbitrarily cranked up the boost. I am sure hat they have studied the ECU behavior as well as the GIAC engineers have and formed their own response to it within the software they implemented in the FVD box.

Furthermore, what would make you imagine that the FVD module isn't capable of detecting any adaptation that the ECU might implement as a result of reduced response from a signal modification? How do you know FVD doesn't have counter measures in their system to overcome this generic piggyback issue that you are bringing up here?

I am not sure where I suggested you are spreading a rumor. I merely have stated that your claim is a conjecture that you haven't backed up with objective facts. I would consider Vbox data or dyno data that demonstrates degradation over time to be objective and non-proprietary information that would support your claim. Without such data, I just have to respond that your claim is conjecture, irrespective of proprietary information you may have about Porsche software adaptation of the control response in it's ECU.

 

I think this is the condition where limp mode is entered. Adaptive responses would amount to something completely different and that is what Tom is referring to. My car has yet to enter a limp mode condition under heavy acceleration load.

 

Deleted my last reply per request....

...and PM'ed you wrs.