Talent

Vehicle:
2017 Mercedes-AMG C43 Sedan (~2,300 km/~1,400 miles)

Modifications:
Eurocharged v3.0 performance engine software, K&N air filters, ASR exhaust flap control

Nature of the issue:
I recently purchased a Dragy GPS performance meter and performed a few runs to test the performance of my C43. I had the oil changed just after breaking-in the engine and this is the first time I've really ran the vehicle hard from a stand-still. The issue that I'm experiencing is that, when I reach ~165 km/h (~105 mph) during full-throttle, the engine reduces power and it feels as if I'm easing-up on the gas pedal. This is substantiated by information on the "Engine Data" menu on the infotainment system as it drops from maximum power to ~270 hp. What is strange is that this issue only occurs if I run the vehicle hard from a stand-still. If I'm cruising at ~100 km/h (~62 mph) and go full-throttle, I can reach speeds >200 km/h (~124 mph) without experiencing a power reduction. I brought my C43 to the Mercedes dealership this morning and they ran a full diagnostic check via their Xentry system and found no issues or stored fault codes and she shop foreman performed a reset of all systems; however, the issue still persists. According to Dragy, the performance is where it should be for this vehicle with these modifications (0 - 60 mph in 3.68s), although quarter mile times suffer as power is reduced before the full quarter mile is finished, and therefore, also results in a lower trap speed (11.91s @ 110 mph).

Any suggestions, thoughts or guidance is appreciated; thank you.

HTXgearhead

I wonder if this is a cooling issue and the car is pulling timing?

What temps are you driving in? The car will cool better at high speeds which might explain why you don't have the issue at highway speeds. Maybe the increased boost pressure is putting a strain on the cooling system?

Gungaslow

Talent

Ambient air temperature was ~10 degrees Celsius. Engine, transmission and coolant temperatures were all in normal operating ranges and the engine was warmed-up prior to being pushed.


The dealership is aware that I had my ECU flashed by Eurocharged. All system updates were done prior to having the ECU flashed and the build date of this vehicle is February of 2017.

Talent

For the benefit of those who have a Eurocharge tune (potentially other tuners as well), I contacted Eurocharged regarding this issue and received this response:

Clearly this information would have been beneficial to know prior to spending ~$2,400 on a tune, but I'm glad they're aware of this issue and hopefully they remedy it shortly.

threefirs

maximus0076

You shouldn't do this. If a tuner sends you an email or anyone , you should keep it personal, remember these tuners and or dealers are only here to help us

Clint Westwood

Did your dealer tell you, "Don't expect us to honor any warranty claims on the engine and driveline."

youngster77

Been considering purchasing a tune from AMR or Eurocharged. Wonder if AMR tuned C43's are running into this issue as well...

Gungaslow

18bora

My guess is those v3 tunes are requesting too much boost for pump gas, the car might be knocking on WOT/ hard-launches causing the ecu to pull timing or go into a safe map. This is just a guess

threefirs

Not a bad guess, but not right. This is what you could expect from a piggy back..

The boost limiters just need to be simply adjusted. The barometric pressure sensor is reading high so it cuts the boost.

18bora

Believe it or not, my piggyback has never done that or go into limp. I'm not personally attacking anyone, just stating facts. Also the jb1 has a built in safety, if you try to be stupid with map6, it will pull back before it's too late and before reaching limp.

Does anyone have a v3 dyno sheet with boost and afr readings? It might tell you what's going on, v3 from any of the big 3 tuners.

18bora

OP, throw a can of octane booster in the tank or 30% e85 and see if you still have the same issue.