jcarroll53

Hey everyone, I have a 2016 C300 (W205) and I've noticed that in rare occurrences if I have it in sport mode and I hard accelerate, the car briefly loses power then quickly regains power and accelerates. No CEL turns on when this occurs, and there aren't any stored codes. I'm using 93 octane fuel, not 89 like some people I know 😅 I've had the alternator tested (grandfather works in fleet management that utilizes hundreds of Mercedes cars and bus motors so he has lots of specialty tools, scanners, etc.), the battery is brand new, the turbo was pulled and checked about 15K miles ago (replaced the water pump and decided to check the turbo for any shaft play and replace seals/o-rings) and found to be in excellent condition. I originally thought maybe it was fuel related, but I read somewhere that it would likely be the sparkplugs.

I do have an appointment with the dealership tomorrow for the Schedule A as well as changing out the spark plugs due to it being time to change them based on the service intervals.

Has anyone else experienced anything like this? I'm just trying to determine what all the potential causes for this could be. Thanks!

Cosworth2000

If you want more power, you need to allow the vehicle to get more air. Look up Flexx on Youtube and you will see everything he has done to allow his C300 to be quicker plus how he added more efficiency to the engine.

Also what Country are you from? Is the car hot when you do such driving? Was it always this way? You might also want to invest in a Peddle Commander to help trick the throttle body into opening faster.

Keith66

When I replaced the spark plugs in my C300 at around 45K miles, I was surprised how much power had bled-off over time. The new plugs made it much more "snappy".

Also, you may just be experiencing turbo lag. Turbo cars generally behave like this. Both my C300 and my E43 react similarly when you just stand on the throttle, not alot happens until the turbos are allowed a moment to spool up.

AzurSL

My 2020 does something somewhat similar which is completely normal. If you are referring to what happens immediately when you floor it, it’s turbo lag, but I don’t think that’s what you’re referring to. It’ll initially feel like the car is gutless and then a split second later you’ll feel the turbo spool and it’ll take off. It’s not a long process, all happens in less than a second.

However, when I floor it sometimes and it shifts from 1 to 2, it will cut power and then give it back to me later like you are explaining. That is TC cutting power. It can get annoying in the twisties sometimes which is why I just disable it in the Command system.

jcarroll53

Hello everyone, thanks for the info. It's not turbo lag, the RPM's actually try to dip to 0. It's as if the engine wants to turn off then turn back on. I just got it back from the dealership today. They installed new plugs, did the throttle body treatment, inspected the impellers, etc. Car runs like a champ now and didn't experience any hesitation under hard acceleration or WOT.

I'm definitely looking into installing a pedal commander in the next month or two.

jcarroll53

Yeah, I actually follow him on YouTube. It's amazing what he's done to his car. I'm definitely looking into getting the peddle commander soon. I'm in Florida, and it's extremely hot this time of year. I've had turbo charged cars, so I'm familiar with turbo lag, but this was something very different. In my follow up reply earlier, I made a clarification as to what I experienced. It was almost as if the engine would completely cut out (RPM's would almost drop to 0, then shoot back up to 1,000). I got the car back today and it's running beautifully.

AzurSL

Ahhh I gotcha! That definitely sounds like there was an issue. I missed the part about it cutting out like it wanted to shut off. Glad to hear they fixed it!

jcarroll53

Interesting update. It started back up again. Although, I notice it mostly in "Comfort" mode.

Cosworth2000

Glad to see the issue you have was resolved and was not about Lack of Power.

jcarroll53

That's the weird thing. The issue came back. I'm trying to troubleshoot what exactly is going on. 😅

Have you experienced anything like this or know where I should start looking?

jcarroll53

I'll try disabling the TC (if I remember correctly, it's the EST setting) and see if it happens. And yeah, I've owned a few turbocharged vehicles before. If it was subtle, the I would just assume turbo lag. But something doesn't sit well in my gut. The weird thing is, nothing is showing up as a stored or pending code.

Cosworth2000

No I have never experience this but I'm thinking since you are loosing power and the engine feels like it wants to die, you should check that there is noting bother the air flow, such as dirty air filter. If you have already replaced the Spark Plugs, the next thing you should check is the Throttle Body.

The only issue is that you need a MB code reader that can look at the Power Module, the ECU and the TCU so see any codes stored.

W205C43PFL

Ya I would do all that and go from there.

To OP, any updates?

jcarroll53

Well, I guess I inadvertently deferred the spark plugs when I brought it to the dealership. They did the Schedule A service (oil change, filter, inspection) and I opted for them to do the throttle body cleaning. It still experienced the same intermittent issues of it wanting to stall out if I gave it too much gas. I've ordered OEM plugs and coils, and I have another shop that is going to replace those next week. I opted for the other shop because the dealer wants +$599 for just the plugs (that doesn't include replacing the coil packs). OEM plugs and coils cost me about $390 and the shop I talked to is only going to charge me for an hour of labor. I'll give you an update when I get the new plugs and coils put in. If the problem still persists, my next step is to replace the injectors and the pump.

The car has 102,000 miles on the odometer (I do a lot of highway traveling), so I'm trying to go based on what the service schedule recommends from Mercedes.

W205C43PFL

Hopefully that solves it.

W205C43PFL

Any update? Did it solve it?