I have 2020 g63
Renntech tune.. now reflashed to stock
Renntech blow off valves
bmc Air filters
fabspeed exhaust.


i recently got it back from a battery replacement and some modules were replaced due to a leaking sunroof that flooded the battery and shorted some things

they installed everything and reset the car, today they scanned the car and no issues came up
i Know there is a bulletin for 2019-2020 g63 for winter gas mix and loss of power

basically it pulls reasonably strong but does not over 350-375hp, can figure out why it isn’t unleashing the full amount. The dealership is confused as well.
I am going to take the blow off valves off and see if that’s the issue

but it seems something is holding it back

has anyone had any issues like this our could help me brainstorm on what the problem is

I have my winter/beach wheels and tires on it’s a beast on the sand. Also have Baja design floods
?v

 

Omg😳, I thought my black with red leather was 💣…but this cole with the black is so dope. I have a 2019, hope I don’t encounter these issues. Good luck on getting yours sorted out, please keep us posted.

 

Renntech BOV - I'd leave this on, this won't have any effect that I can think of.
BMC Air filters - I'd swap these out for OEM. Not a huge fan of oiled filters and there are some reports (Google it) that BMC filters disintegrate and can get clogged in the engine. Not worth it in my opinion.
Fabspeed Exhaust - I've heard of someone installing an aftermarket exhaust (Akrapovič) and having a loss of power as you mentioned. I'm not quite sure why this is - you want to lose back pressure for turbos and the freer flowing, the more HP.

There also was an emissions update that updated all the software, including the OEM tune. Was that done around the same time (the recall)?

I'd say unplug the negative battery cord for 30 minutes or more, then re-connect it and drive it around for a few weeks how you like to drive - I'm wondering if the ECU will re-learn your driving habits and get you your power back.

That's all I can think of other than having a coding/tuning genius to analyze your log files.

 

I'm not sure if its the same but I have an E63s, and when I had the same problem it was the valve getting stuck shut.

 

Exhaust valves are limiting your power. Which fabspeed exhaust did you get? Did you retain the factory valves? If they were unhooked you'll have soft faults that wont set a CEL.. but will limit your HP output.

 

im actually have the same Problem on my 2020 g63 AMG. I installed a aftermarket exhaust and the car is doing the same exact thing. Doesn’t go over 367hp. Were you able to get this issue fixed ? If so , what was done to fix this issue ? Thank you

 

I installed a aftermarket exhaust on my 2020 g63 ( brabus clone exhaust ) sounds amazing. But also now on my HP and TQ display the HP shows a maximum of 367 HP. Any idea what this can be ? Why am I having a loss of power ?