Hello everyone, first of all, greetings to all from Colombia. My name is Santiago, and I’m new to the forum.

I couldn’t find a better place to post this, and I apologize if my English isn’t the best.

I have a 2012 C63 with a Weistec Stage 3 Supercharger with 22.000 miles

Recently, I’ve been having problems with it, and no shop has been able to diagnose or solve the issue, and it’s really driving me crazy to the point of considering selling it.

Here’s a list of the issues I’m facing, which are mostly related to the transmission and acceleration:

1. When I start the car, whether it’s cold or warm, and I select Reverse or Drive and press the accelerator, the car starts revving 3-5 times on its own and tries to stall but doesn’t, then it runs normally. This also happens when I’m driving and I come to a stop and then accelerate again; I feel the car jerks, and then it starts moving smoothly.
2. When I’m driving, the third gear feels endless, and it lacks power, as if it’s not advancing (it is), but the transmission feels very sluggish.
3. When I’m in second gear and accelerating gently, the car starts to jerk as if it’s not getting enough fuel or something, but if I press the accelerator harder, it reduces the jerking. This happens a lot on inclines.
4. I also want to ask if it’s normal for the car to be doing 5 miles per gallon in the city? I feel like it’s running too rich, but the Weistec tune hasn’t been touched since the car was built.

Here are the things I’ve checked without finding any issues:

• Transmission and engine oil levels
• Supercharger oil change
• Supercharger pulley and belt replacement
• Adaptive transmission reset (10-sec pedal reset)
• All four oxygen sensors are fine
• Injector cleaning
• Air filter cleaning

The last thing I have yet to do is the transmission software update, but Mercedes-Benz has told me it could make things worse and can’t be undone.

Any solutions for this problem?

 

Sounds mostly tune related i would talk to a real tuner and get this issue fixed you are not the only one who has issues with Weistec supercharger tunes contact Barry with 86tuned he has fixed a few of these already follow the link unleash the power and performance with eightysixtuned

 

This sounds like a transmission issue of some kind to me. When you checked the transmission oil level did you do that with the car running on a hoist and also making sure that the transmission temperature is at normal operating temperature (Ie, not cold)? The engine should be started and you should put your foot on the brake and then shift from Park to Reverse to Drive and then back to Neutral. Raise the vehicle on the hoist and let it warm up. When you remove the drain plug a small dribble of fluid is the correct level. No fluid coming out may indicate that it is too low in which case add fluid until it dribbles out. Install the drain plug. If that does not make any difference then you could have an issue with the valve body in the transmission. It's not unusual for some part of it to fail causing weird shifts, rough shifting etc. It could also be the wet clutch. With a supercharger added you are putting way more horsepower through the transmission so that's always the next weakest link in the drive train.

 

It sounds like your transmission is slipping. Many people upgrade their transmission at that power level to handle the torque.

 

I too have a 2012 Stg3 Weistec setup and there are some weird things from time to time. But I've not seen this one before. It definitely sounds tune related. Usually with the transmission issues you will get some pretty serious slippage, with RPMs climbing between shuddering on acceleration. I had that with my 2011 model when the torque converter began going out. But I've not seen anything like that with the wet clutch in the 2012 model. Does your Stg3 have the "Trunk Ice" or any methanol injection system? I had some weirdness when I first got this one and found that the plinth in the AEM injection system was not seated in the injector properly, allowing random amounts of methanol into the blower. I replaced the injector (v1) with a v3 injector and it resolved the perfomance issue. As for your in-town fuel consumption, I get around 12mpg average whether I am running highway or in town. But it depends a great deal on your driving style. I've gotten as low as 8mpg and as high as 17 at times, with average at 12 or maybe 13.

Check the tune first as that will make the most sense.

David

 

If these are all new problems and weren't present previously it's pretty clear the transmission is toast as tunes dont just go bad. Typically 3rd gear is the first one to go. I've killed 2. Not as bad as yours sounds but under full throttle it would flare up and bounce off the rev limiter before very slowly slipping into the next gear. Particularly the 2nd to 3rd shift. Replace the mct unit as well.

 

As for tunes not going bad, that is normally true. But I found that the tune had corrupted memory in the ecu that made star diags show some pretty outlandish error codes with impossible values in the codes, like temps that would have melted aluminum had they been real. And they were impossible to clear, showing up every time i ran diagnostics. This kept happening until we rewrote the ecu. So yeah tunes may not go bad but it doesn’t mean there is no corruption. We still don’t know the cause of that problem, only the fix.

David

 

this is when tuners don't run complete map
tuning. They tune a few maps and then smooth or auto fill some more and or don't even touch entire other maps. You end up with multiple values with vary large margins or inputs and the ecu will go bonkers. This can definitely cause crappy shifting/hesitation or other weird things. Definitely worth trying first get it tuned properly then go from there. Does sound like the transmission may be starting to go and will need a rebuild but kinda to be expected running stage 3 power outputs

 

no mention of fault codes or strange values. "no shop can fix it or figure it out" . Only issue is in 2 particular gears. Only thing we're not clear on is if it has always done this or recently started. Im not saying ****ty tuners dont exist. ofcourse they do. They also charge you extra to fix mistakes they made the first go around and offer you a discount on your next car's tune in return. Just saying 10yr old cars with a 60% horsepower increase over factory tend to break and destroy parts. It doesn't sound like your typical "my car ran perfect, than i got XXRXXHXXGED tune and it runs like poo, do you think it's a bad tune? it drives normal when i flash it to stock. I'm think my spark plugs are bad" issue lol.