Thank you, I'd like to hear what he has to say as well.

 

Very interesting thread. I'm thinking about having my 4.2 XKR tuned (remapped, to us Brits), I wonder how much of this knowledge exists with tuners this side of the pond.

 

I'd just like to say thanks for taking the time to write this up, quite an eye-opener!

Something tells me this guy is going to be in high demand shortly.

 

Very interesting.

Sounds like it's about a Bosch PCM (aka ECM), whereas the earlier R cars have Denso (some with twin 32-bit & some with single 32-bit cpus).

When did each of the cars move away from Denso PCMs?

 

He actually lives in England and writes the majority of the tunes that you out there.

I've realized the tuning world is like pyramid with only a handful of guys who actually do the programing.

 

The german tuner Arden uses an additional ECU. Performance increase of 24 kW (33 hp), torque increase of 50 Nm and optimization of the complete torque profile by using an additional ECU.
I haven't read anything yet, that the engine management was using safe modes of its own ecu when tuned like that. The performance gain is noticeable without side effects. Anybody heard anything else yet? I am thinking of upgrading that way. Comments??

 

I'm more than happy to share my experiences and hope it's helpful, I've learned a lot from this forum and its members.

 

I'm not sure how the Arden system works I'll have to ask. I believe he can also send you a tune that you can keep. The TCU tune to go along with the ECM is a must.

Where are you located? I'll ask him which dealer he has local to you.

 

I'm located in Muelheim an der Ruhr in Germany

 

By additional ECU, I assume he means a piggyback ECU. Essentially, it plugs into the wiring harness before the ECU and manipulates the sensor inputs to the OEM ECU to trick the OEM ECU about the actual operating conditions of the car. It can also adjust the timing and injector signals coming out of the OEM ECU to put into effect its "tune." Piggyback ECUs are not all that uncommon. I ran one on my highly modified Audi to manage a few parameters of the custom tune I ran as I changed components on the car. They are cheaper, and depending on what you get, user adjustable. Generally, however, piggyback ECUs are held in lower regard than true ECU tunes and are more limited in what they can do.

Given the current issues, it seems that, unless someone truly cracks the OEM ECU, the best option for the hardcore performance enthusiast may be to run a standalone ECU. Of course, the warranty disappears at that point.

 

Just to help complete the picture: checksums are used (as their name suggests) to check the integrity of a data file. They are calculated by reading the entire file and performing some sort of running total calculation to give a 'fingerprint' for the data. if you change just one bit in the file, you'll get a different checksum. So, if the map file has a bad checksum, the ECU will assume it has been corrupted and should not be used.

Something I've read in another thread: a valid map includes a reference to the car's VIN. That would tally with the comment that the checksum can only be calculated with the ECU in the car (presumably so the VIN can be appended to the map).

 

If it was a really tailored piggy-back system, with the OEM plug connectors, you could simply unplug it & no-one would ever know it was there....

To date I think Arden are the only ones going down that road, and it's serious $$$$'s

 

A standalone ECM like a Motec would be awesome, I had one in a Corvette and could do anything I wanted to. If course these systems are much more complex as we have the TCU and DCS tying into the ECM.

The TCU tune is awesome, I really noticed it driving home yesterday. The shifting is so much quicker both up and down. Its no DSG but its quick.

 

Hey Max, Can you give us an update on how your tune is holding up?

 

Not sure about Max but my tune has been consistent since day one. Car pulls very hard and has no issues at all. Mine is a 2012 model, maybe the '13+ have a different ECU as was mentioned a few posts above.

 

They do have a different ECM somewhere between 2012 and 2013 they switched to Denso.

Everything is holding up just fine and I've put about 500 miles on the car, including a track day.

 

For the record I have no problem with Eurocharged, the tuner that was here even said it was a good tune just needed a few tweaks to "smooth" it out. He made the base flow fuel change, and a change to the rear O2 sensors since I have 200 cell cats, but it wasn't working due to an incorrect check sum. That was all evident by the punny 380HP dyno run when I brought it into the shop. I just wish Jerry would have called me to explain, instead of sending me an email stating its impossible and the car is fine. The dyno shows otherwise, and I'm still pissed but since I'm using his "fixed" tune so be it, but I'll never go back with any car I own.

 

I hear ya....I emailed them with a link to this thread and he was dismissive about it as well. I just wonder if it has something to do with their knowledge of changes between the different ECUs. Maybe they haven't looking into the differences between them and instead made assumptions.

I have no clue. But I would find it hard to imagine both ECUs are identical when it comes to how they work (with regard to reverting to safe mode tunes, etc). I plan on getting another dyno once I have some time and it cools down a bit. No sense doing one in 100 degree heat. I'll wait to find a day that is similar to my base dyno when the tune was installed.

 

Lol, so that guy is a tuner who makes his living by tuning cars, he fly’s from the UK to America to tune his customers car but does not want his name mentioned?
Why?
Perhaps because he would look stupid by telling the customer (and the forum community) that everybody is dong the checksums wrong and with a correct checksum he can make more power?

With a bad checksum the car will not start let alone drive and would be full of errors (It sure does not add 50 instead of 100hp) and besides…. Checksum has nothing to do with power.
Even if he found some way to make more power, why would he make up such BS?

+ Fuel trims -4.7 will cause no problems. That’s even normal for stock cars. It sets no code or anything. If fuel trims go over 30% the ECU may set a code. This whole story stinks like so often on forums… Would also be interesting to know how he reads and writes the TCM. Whenever we hear that a tuner was working for Bosch and Porsche, we all know its BS.

Post the tuners name/company if his product is the real deal, until then we ALL know its BS.

 

Max - I've tried to let this go but people keep bringing it up, so I figure I need to set a few things straight. I think the forum should know that you and the owner of RSC are "friends", according to an email that you sent me. You have mentioned to me in emails that EVERYTHING they have sold you and done have been subpar. You mentioned that you wasted $10,000 there and that you never want to go back. Now, with all of these things that you say have happened to you, you still bring your car back to them to "fix" my software. Keep in mind that I have emails from you stating they attempted to tune the car more than once and your best trap was only 117. So, a company that couldn't tune your car the first few times you visited there has now managed to understand the software and can now tweak my tune and make it better. Hummm……

For the record, I have tuned over 6000 European cars since 2007. The fastest cars in the world have our ECU software on them (Underground Racing Twin Turbo Lamborghini’s). I sell private labeled tuning software to many big tuning providers who advertise my software as their own. I learn from my mistakes and I strive to make my software better all the time. With that said, I know I don’t know everything about tuning and I do learn something new every day!
Now, I have a few questions that the forum needs to have answered so that everyone can move on. I personally think that you gave my software to RSC and are now using my file on their customers cars. It’s really the only thing that makes sense to me. The forum is being misled into thinking that RSC are now the go to guys for Jag tuning using this unnamed guy that they flew into town.

Please answer these questions or contact your mystery man to get them answered.

1. Which checksum was bad?
2. What is the memory address of this “bad checksum”?
3. What is the memory address of the maps the car uses to default to stock?
4. What is the memory address of these “higher performance tunes already on the ecm”?
5. What tool does he use to write to the TCM?

Let’s start with these questions because I don’t think any of them will get answered. If they do, it will be with more made up information that we will be here to disprove.

If you have a bad checksum, the car will start once if you’re lucky. Most cars won’t start at all. Do a quick google search and you will see.

Max – May I have your permission to post screenshots of our email communication? I would like the forum to know that I did not blow you off. I explained to you that what you were saying was impossible and you chose not to believe me. Now, you are bad mouthing my company on public forums, with inaccurate information and SOLELY promoting the RSC tune.

I’m sorry Max… facts are facts. Please have your guys post the information we requested so that your claims are proven.

Forum members considering tunes.... please contact as many tuning shops as you can and ask to speak to the tuner there. Ask that tuner what will happen if you flash an ecu with a file that does not have the checksum done.