jake732

Hey all, I LOVE my c43 coupe... but at times I wish I could give it a bit of a boost in power. Are there any performance mods out there that WONT affect the warranty?

munis

Okay, I will try to answer this properly as this question is asked way too often and I do realize there is not one answer for it. Here is what I know about it:

Any of the full tunes will 100 percent void your warranty if you need any big repairs or if mercedes just randomly decides to dive into it, going through the warranty voiding experience myself, I know exactly how mercedes finds it. I will do a write up soon on it. First thing they will check if the seal is broken during tuning, which no tuner currently is capable of doing without breaking it, meaning most of the time they do not even need to go further than that.

Coming to piggyback's, you will always get away with medium sized repairs, like sensor and wiring harness issues but again for any big part damage like transmission and turbo, don't expect Mercedes to honor it ***** nilly, not because they can't but because they want to know what caused the failure for future R&D. Also remember, there are multiple modules in the car that logs peak values recorded which can be be later read. So for example, you blow the turbo, then if you take it to mercedes, they will look into the logs and see the logged pressure values. But what a lot of tuners will tell you is that the piggy back unit is fooling the ECU to think everything is hunky dory, keeping everything within safe parameters while it does it, so it should appear normal. Actually that is not the case, the piggyback is fooling the ECU into requesting more boost, but what is not considered is that there are 2 pages full of other parameters that the car recorded as well. Mercedes can correlate and analyze the additional requested boost to the other parameters in that given moment and would know right away that the requested boost is too high in a given condition. This can also happen because of a faulty O2 sensor for example, but Mercedes can simply test that 02 sensor to verify its readings and if that is line, then they know right away you have a piggyback.

You can always go for piggy back tuners that does provide warranty like Dinan who will 100 percent honor the claim if it is because of the tune, but that still does not save you from flagging your car if you go in for a big item repair as Dinan pays for the repair to be done at a Mercedes dealer.

The one and only way to keep your warranty and still tune the car is this: get a second brand new ECU. This is not easy as the new Mercedes ECUs are considered a TRP (Theft Related Parts), so you would need a dealer's authorization for ordering it. You cannot use second hand used ECUs from junk yards either for the w205 platform because they still do not have virgin files for our ECUs. So the only option is to have a local third party shop that is in very good terms with the Mercedes Parts department order a brand new ECU for you. Then you need a local third party shop that can do online SCN coding, a few are available in US and Canada, not everyone has access to it. Once that is done, you have two ECU linked to your car with identical files. Keep the original one safe and tune the other one. If something breaks, put the old one back in and go in for the repair, to my knowledge not even the engineers in amg headquarter have any means of proving otherwise.

aggies15

That's not entirely true. The Magnuson-Moss warranty act prevents dealers from denying warranty claims because of modifications (if the modifications were found to be unrelated to the issue). Mercedes would have to definitively prove that your tune caused whatever issue arose with your car. It is illegal for Mercedes (or any car manufacturer) to void your warranty entirely because they found out you have a tune. They, however, have the right to refuse any repairs that were proven to be caused by your tune. There is a big difference.

MASSC450

I can believe everything you've stated in your original post (especially about an ECU reflash) BUT this statement. The dealership may have a gut feeling you've used a piggy-back, but can't prove it 100% if it's not connected (and you haven't admitted to anything). It's their job to prove whatever you might have done caused the failure, and as long as you haven't incriminated yourself (left the piggy-back on for the dealership to see), it would be a tough for the dealership to prove without a doubt you've used a piggy-back tune.

munis

I should have mentioned that I am in Canada where the magnusson moss does not apply. In my case Mercedes found out I had a full ECU tune and issued me a letter stating my powertrain warranty for any parts directly affected by the modification is voided, which is pretty much everything to do with the engine, it would not be hard to blame a turbo or transmission blowout on the tune. Small Powertrain repairs and any issues with the car except powertrain I think will still be honored.

The main issue with warranty is not the warranty support itself however, parts are not the most expensive, like with tuning these engines, the major components that will mostly like go first is the turbo or the tranny which wouldn't make you a broke to repair. Tuning is something where you pay to play, so replacing a turbo or tranny isnt the end of the world.

The main problem is with trading the car or a returning a leased car once the car is flagged. Once the car is flagged in the system, returning the car or trading it in will be extremely difficult. To the point Mercedes might refuse to take it back period. Atleast that is what my understanding is in my experience. If you guys know otherwise please do share.

PaulE550

Just a quick couple of questions. Could MB not simply correlate all the captured log data at time of turbo failure, as everything is likely date and time stamped, and compare it against other instances of known piggy-back usage that they have undoubtedly found over the years and, in all likelihood, have stored in some historical database they preserve just for just this sort of thing? If they can then demonstrate the data logged is consistent with previous known instances of piggy-back usage that led to past turbo failures, wouldn't that be sufficient to deny a warranty claim for a big ticket repair? After all, piggy-backs all basically function pretty much the same way to achieve additional power, so the data patterns logged would be consistent and look quite different from the standard logged data of a purely stock vehicle. I just would think someone at MB corporate would have realized a long time ago, that collecting and storing this type of data to avoid the expense of costly warranty repairs, due to what MB considers illegal mods of their product, would make a lot of sense.

threefirs

yes and no. The MB dealership isn't a court of law, and they can really do whatever they want. You can take them to court and tie up thousands of dollars, time and be without a car to fight it but they can easily say it's the piggy back and ask you to pay for the repair/service at the time of diagnosis.

munis

You are absolutely right and that is exactly how they do it. If they need data from previous tuners, I do not know, but they can absolutely correlate the engine data from the current logs to the logs they had during the R&D of this particular engine. They will have gigabytes of logs on the engine and the engineers at headquarters know exactly what's up. They know exactly how much boost the car should be producing in a given condition (temperature, air moisture, humidity, air flow etc.) and all that is recorded.

MASSC450

Do you honestly think a dealership is going to go through these strides, for lets say a blown turbo, trying to prove a customer might have used a piggy-back tune...one that has only been around for about a year? I highly doubt it.

I doubt it even more if said owner was in their 40 - 60s, a repeat customer, no prior similar incidents, and the vehicle showed no sign of track use.

munis

I didn't even have blown turbos or any major component fail but the lengths to which Mercedes went to prove I was tuned was nothing short of astounding. This entire check if I was tuned or not was triggered by me simply asking for the latest ECU update nothing else. The entire ordreal was huge and it will take me a while to write, that is why I am not posting it. I will write it whole when I get a chance.

MASSC450

A dealership cannot void a car's warranty (only MB can do that), but they can "decline" to perform service...making up whatever bu11$h1t story they want to justify denying the work. And I can just go to another dealership that is more hungry for warranty work.

You people can split hairs all you want over the issue of running a piggy-back tune, but in the real world, as long as the piggy-back is not present, it will be extremely hard for the dealership to prove you were running one.

MASSC450

Really? You said you had your ECU reflashed...how hard is that to detect? Extremely easy...that's how hard.

munis

I will write about it haha. It was easily detected, yes. But they went to great lengths to PROVE it.

Lazz83

Yes I agree and don't forget dealerships make huge money on warranty work from Mercedes Benz, so why would they want to finger someone or even look deeper into an issue. The dealership makes money off the labor & parts of the repair, why would they want to try and C**ck block that?

I have had several modified vehicles in my life and dealers where ignorant to that fact, they never knew anything out of the ordinary was going on. I used SCT Tuners in the past on Ford products and when the vehicle went in for service or repair I would just flash the ECU back to stock. Never had a problem.

Unless it is absolutely blatant like having a full MSD ignition on a vehicle under warranty or bringing it in for service with a computer re-flash- they should not care. I have had several stock vehicles with complex engine problems, that I brought to many dealers and they did not even take the time to properly diagnose it- I eventually found the problem out myself by using web boards and doing my own investigation. I was blown away that these dealerships could not find what was a common and known problem on these particular engines. They didn't even analyze any data, just had the mechanics take it for a test drive and they stated everything was ok- when it clearly was not.

So I don't know why people think dealers have the time to scrutinize data logs and other parameters. Of course there is always the chance you can get caught, but in my opinion it has to be a blatant red flag.

I am not fully versed on the tunes that are out there but from what I have read on this board, the big three tunes OE, Euro and AMR stay somewhat on the safe side so you won't destroy a transmission or blow a turbo.

MASSC450

I'm not questioning what happened in your case, but I highly doubt the dealership or MB would go through such lengths trying to prove a piggy-back tune was used, especially when it was removed prior to taking the vehicle to the dealership.

It's much easier to build a case when an ECU has been modified...for sure...

Kevin Solopolo

solid response!

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DRLC43

munis

Couldn't have worded it better.

threefirs

This, 100%. Sure, you might get away with it. But it's very misleading and unfair to tell people looking into a tune that they're completely safe with a piggy.

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threefirs

Sounds logical. So while you're going to court for 5 years, the car will sit with a blown motor, and when the lease expires, MB will be happy to send you a 70K invoice for the damage to the vehicle. All while, you're in the wrong for running a tune on your vehicle. Smart guy you are!

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PaulE550

Thanks for your response, While I agree with you that most dealerships probably don't care one way or the other what caused the problem, as long as MB corporate reimburses them for the costs of any warranty repair. I guess it all comes down to how serious MB corporate is about trying to discourage mods of their product and how much pressure they put on their dealerships to try and discourage it. Again, for small stuff like a blown turbo, it is probably not worth their time and effort. However, for something running more than say high four figures or low five figures, it might be. Depends on what current MB corporate policy is related to threshold cost of a warranty repair in order to trigger certain mandatory actions by the dealership.

Just as an FYI, the process I laid out wouldn't be very intensive for the dealership to do. All their service guys would need to do is plug the car into their on-line diagnostic system and all the ECU and data logs can be uploaded to whomever at MB corporate does this type of analysis. That is the extent of the effort expended by the local dealership's service department. Once the data is at MB, the whole data analysis / comparison process shouldn't take more than one to two hours tops, as their systems are just looking for anomalies from standard performance data for the engine / vehicle type relative to the data logs. Only if the ECU data versus all the log component log data doesn't match, which it wouldn't if someone had a piggy-back attached at time of component failure, would anyone from MB corporate do further data analysis against the historical database to confirm it matched. That is another automated comparative analysis process. So just wanted to let you know that it is not as onerous as you may think. Again, thanks for your reply.

18bora

My son got his car tuned by a Dinan-owned company, they had a 30-day-trial "money back guarantee". Long story short, 2 weeks into the tune, we decided to go back to stock and get our money back. They had no problem flashing it back to stock and "we'll send you a refund check by mail"........ 5 months later, a dozen of emails and 20 long/hold phone calls, we got our money back minus "labor". While it wasn't a lot of money, I just can't imagine filing a blown turbo or engine claim with them or any of the other "tuners" for that matter. Good luck having any of them honor a claim, after you prove their tune caused a failure.

Thank, but I'll take my chances with a piggyback and MB