Cats & Resonator & Tune discussed with a MB tech
 

A good friend of mine has been a tech with Mercedes for close to 10 years. He works on a lot of AMG's and has dealt with all different types of issues. I spoke with him about my new CLS AMG and his thoughts in regards to cats/resonator/tune.

RED FLAGS
Modifications/removal of cats or resonator is a big red flag.
He highly warned not to do any of this since it sets off check engine lights and may cause other issues with the car. He also said that if you were to take the car in for service that it might be flagged into the system and cause you future warranty issues.


In regards to an aftermarket exhaust, there should be no issues or red flags.

I was talking to him about the motor and was quite shocked how expensive replacement cost is (north of $50k). The motor can't just be purchased in parts, it comes as a complete replacement with intake, ecu, and every other possible part......

Most mechanics and dealers don't check for tunes since they can't really see beyond a certain point. If a high dollar car has an unusual large issue with a failed engine or transmission then they would call over some head honchos from MB and they would probably arrive the next day to examine the issue. These guys have very good access to look into the ECU history and check for timing and ect to determine if it was tuned or to see what occurred.

He explained that this is extremely rare since the motors and transmissions are built very well and almost bullet proof.

He said with a moderate street tune you should be fine as long as it's done right. No race gas or aggressive track tunes.

The CLS 63 AMG is still fairly new and he said in another 6 months is when they will start seeing more of them for service and ect.

well, our dealer doesn't valid the warrenty for deleting cats because they know if it isn't under warrenty we are not forced to take it to them for service and being raped for service.

imagine minor service ( oil & filter ) for $750.

however if the car is scrwed because of mods, then they will start giving us bad time. other than that they don't even discuss about the mods. they do their job and get paid for service.

very interesting, I'm sure the tuned will show up to poke some holes, But I've always kind of thought tunes and all the aftermarket go fast mods were/are sketchy, look good mods are one thing, but screwing with all that stuff wiggs me out.......

so you mean that, if we cut the cat and let's say we make straight pipe by cutting the resonator out, so it is voiding the whole warranty on engine/car?

Not if it's tuned properly. See the V-Tech Stage 2 tune ;)

If my car ever suffered any type of failure like that I assure you the ECU would be flashed back to stock before the car arrived at the dealership :y

He's spot on with this. Most of the tunes out there are still considered "conservative" and you maintain reliability! :y


It's illegal for them to do that. Read up on the magnuson moss warranty act ;)

This!

Resonator removal does NOT set off the CEL as they are down of the O2 sensors... only the primary cats would and we dont have secondary cats.

And plus one on the magnuson moss... the modified part must lead to the failed warrantied part.


Some techs in the business think they are god... some listen to their service advisors who ultimately can generate more income or wash it away.

Well said Vic. This is so true!

No, this most likely won't be the case. It's just a red flag at MBZ. To the others that might want to debate this, interpret it how you like and how your service department works.

The Magnuson Moss will provide protection but when a modification is debatable, hire up a good lawyer. A lot of vette guys know this too well.

If a $60k motor gets blown (highly unlikely), it might be a good idea to know what mods should be done with caution. That's a lot of freaking dough!!!

I'm considering a tune in the near future as long as feedback stays positive.

Also a second ECU is doable :y:D

yup we do actually have secondary cats :y

well to be sure,

the set comes like this O2 sesonr/cats/O2 sensor/Cats. the 2nd O2 sensor is in the middle of the cat which is empy in the middle.

we have 2 small cats on each side. but if you look it from outside you will see one whole bumb nick but from inside it is empty where the seconed O2. similar to SLR cats :D

+1

it's all about the tech you deal with. build a relationship with your tech and tip moderately to keep motivated.
my m3 is fully modified, i bring it to service all the time and thanks to my friendly personality my tech has never gave me any warranty issues.