will respond in PM.

 

Scott can you please explain why the over rev range counters register high range spikes when in fact the engine has never gone beyond the rev limiter nor been mis shifted on any down changes to cause an over rev spike. Are you aware of what can be done to correct the recording of these false over rev events? I'd like to know exactly what it is thats within the ECU that conflicts between the tune file and the counters that is causing this to occur. Are you able to elaborate?

 

I have a general question about the relationship between Porsche and tuners. Why is tuning so clandestine? I would think that if Porsche charged a fee to become an aftermarket partner or whatever you would call it, they could make very high margins providing support to all the tuners. Additionally, money could be made selling super-extended warranties that would allow owners to mod up without jeopardy. I am sure there are good business reasons why this is a bad idea for Porsche but I don't see what they are.

 

Let me count the ways....

First, anyone that knows anything will not share that with other tuners- it is their 'proprietary edge'... since what tuners do has no 'protection' (ie cannot be patented nor licensed) it is kept secret.

Second, Porsche will not let these secrets out for industrial competitive reasons (ie other applications)

thrid, Porsche would be legally 'on the hook' if they permit knowledge that allows mods to be performed. You can have all the disclaimers you want, people sue. Porsche has infinitely more to lose than ANY tuner.

Fourth, if porsche opened this up then tuners could get around their tamper codes, modification detection.

Finally, would you spend $20k for a 'super' extended warranty? If I was porsche and I had unlocked the DME to allow a tuner to grenade your motor at will, that's what I'd ask.

 

My understanding (as limited as it is), is that once the RL has been raised or manipulated, all of the calibrations for over-revs 1-6 are thrown off. Hence, numerous false type 4,5,6 codes, when really it was a type 1 at best.

 

No way is P going to do that, liability for sure, but emissions is such a huge deal in many countries around the world. Total crap IMNSHO. Most of the manufactures have taken steps to secure their engine computers from "tampering". Some very smart people that rightly so consider what they do "intellectual property" and with no protections are going to keep what they do top secret. That's not to say that other tuners can get a hold of a car with a competitors tune, download it and analyze what they did .. I'd be willing to bet there's more of that going on than you can imagine.

--CC

 

Thanks Chris. I believe you are correct there is incompatibility between the tune file and the range counters. The big problem i forsee is when a warranty claim needs to be made or, a request for goodwill is asked. Given the number of over rev spikes recorded i can only imagine things wouldn't go down too well. I wonder just how many users of these tunes are aware of the status of their range counters? Also is there a cure for this problem in the pipe...?
Hopefully Scott can add something here.

 

Awesome thread. Thanks fro doing this.

I have several questions:

How far can the DME "adjust" before throwing a code. IE what happens if you add a simple boost controller to a stock file? I assume the engine will compensate at least for some time?

Can you make a tune which is basically stock parameters with increased boost acceptability? How far off are tunes from these "stockish settings besides more boost?

Can you adjust cam timing at all on the cars compared to factory settings or is that a mechanical thing?

Some tuners have established themselves as more "powerful" than others. And I have heard of a few, but not many blown engines, mostly centered around only 2 tuners. NOT throwing rocks. But I've been here long enough to know that these are generally pretty silent. I your opinion are these engines running too much boost? Timing? Deadened knock resistance? a combination? bad fuel?

There was a time when rev limits kept going higher and higher on the 996T motors. As high as 7600. This trend seems to have subsided after a few breakdowns. What do you consider a "safe" rev limit? I have mine set at 7,000 now.

Can the 996T support boost by gear limits?

I'll keep them coming. Thanks again for doing this! It's great and super informative.

 

I'd be curious to hear a response to the overrevs as well. I guess it's possible that raising the rev limiter could mess up the overrev calibration but is this known for sure? It seems to me that these would be independent events but that's just a guess. One way of testing would be to record your current overrevs then take the car to 6900 rpms and not shift, just let off the gas and don't go through neutral. Then see where the overrevs are recorded. It could be that a slight delay in letting off the gas after depressing the clutch, could send the motor's inertia into a higher rev range. Just a thought.

 

Possibly. But once the ignition is killed instantaneously upon spiking the rev limiter whatever inertia is present is not going to rev it to 9000 rpms to record a 6. It would also have to be one hell of a full on downshift to cause that as well. There's definitely something going wrong between the tune file and the range recorders imo....especially if you know as fact you havent gone anywhere near those rev levels. It'd be great to hear the "word" on this from the tuners....but no one seems to want to talk about this issue.

 

I don't know how plausible it is to get to 9000 rpms if you shift just before rev-limiter (say 7199) with no load. Overrevs seem to be a bit taboo unless your considering buying a car with DME readouts that show overrevs--lol.

 

lol indeed. It seems these days so much emphasis is being placed on DME readouts when it comes to buying/selling one of these cars when in true essence its all just mumbo jumbo 99% of the time particularly if the car has had a tune file. It really becomes anyones guess whats really been going on behind the wheel/throttle. Maybe theres some value in a compliant DME readout when sitting on a bar stool chatting with your buddy that has a DME with spikes all over the ranges.

 

Yeah, that pretty much says it.

 

I have an odd question... being an old (I mean really old) software engineer... is the source code written in a high-level language and then compiled? Are there drivers available for the various sensors and doo-dads? Is most of the code comprised of look-up tables? Writing this sort of code sounds like a lot of fun (in an extra-geeky kind of way). Thanks, Steve