Car Jolts During Hard Acceleration
Thread Starter
Newbie
Joined: Apr 2017
Posts: 5
Likes: 0
C300
Car Jolts During Hard Acceleration
Hello!
i am currently driving a 15 C300 with 25k on it. A few weeks ago I started to notice a single jolt during hard acceleration. This later turned into multiple jolts usually between 70-80mph. The vehicle will shift back and forth as many as four times. It's almost as if the car is struggling to accelerate. This evening on the freeway I decided to push the transmission to the limit and see if I could notice a change in the gears or fluctuation in RPM when it happened but nothing. It jolted four times tonight at about 75mph when I had the pedal all the way down. After this it appeared that the car struggled to maintain any speed above 70mph. I also turned off all music and noticed a humming during acceleration above 70mph that wasn't there before. I've already had it checked out by the dealer. Tech put on 16 miles but couldn't locate any issues. No codes, lights, or anything. Any thoughts? I'm hoping this new humming or a drive with a tech can identify what's going on. My guess is the transmission is failing pretty early.
i am currently driving a 15 C300 with 25k on it. A few weeks ago I started to notice a single jolt during hard acceleration. This later turned into multiple jolts usually between 70-80mph. The vehicle will shift back and forth as many as four times. It's almost as if the car is struggling to accelerate. This evening on the freeway I decided to push the transmission to the limit and see if I could notice a change in the gears or fluctuation in RPM when it happened but nothing. It jolted four times tonight at about 75mph when I had the pedal all the way down. After this it appeared that the car struggled to maintain any speed above 70mph. I also turned off all music and noticed a humming during acceleration above 70mph that wasn't there before. I've already had it checked out by the dealer. Tech put on 16 miles but couldn't locate any issues. No codes, lights, or anything. Any thoughts? I'm hoping this new humming or a drive with a tech can identify what's going on. My guess is the transmission is failing pretty early.
MBWorld Fanatic!
Joined: Mar 2017
Posts: 1,026
Likes: 282
From: Omaha, NE
'16 AMG GTS, '21 AMG GLE53
If the RPMs are steady and power drops out, that sounds like a misfire situation. If RPMs are surging, sounds like tranny problem. Either way, I'd think codes would be flying left and right when it happened 
Thread Starter
Newbie
Joined: Apr 2017
Posts: 5
Likes: 0
C300
Trending Topics
MBWorld Fanatic!
Joined: Sep 2014
Posts: 1,822
Likes: 33
From: Whitefield, NH
2015 C300 Sport: Palladium, Premium, Multimedia, Leather, BLIS
Try a reset in the car by holding down the CD eject button for several seconds. After the reset, try re-establishing your connection.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
MBWorld Fanatic!
Joined: Nov 2015
Posts: 1,193
Likes: 302
From: Oklahoma
2016 C300 4Matic traded in for a 2022 E450 Coupe
Thread Starter
Newbie
Joined: Apr 2017
Posts: 5
Likes: 0
C300
Alright so I got back from the dealer yesterday and apparently someone had the same issue and they were able to pull a crank shaft sensor code. The car has to accelerate long enough through the jolts to pull the code. It's been replaced and no further issues noted at this time.
Former Member
Joined: Jan 2017
Posts: 0
Likes: 94
CLS
Alright so I got back from the dealer yesterday and apparently someone had the same issue and they were able to pull a crank shaft sensor code. The car has to accelerate long enough through the jolts to pull the code. It's been replaced and no further issues noted at this time.
Super Member
Joined: Oct 2014
Posts: 787
Likes: 110
From: BNE, Australia
W205 C250BT
Intermittent issues can be a real pain - especially if you're trying to show a dealer or service centre and then there's nothing wrong when they drive the car. I would try the following:
- Get a Bluetooth OBD dongle and buy the 'Torque' app. There's an additional plug in which lets you merge video and the diag data onto the one screen.
- Go out, do some testing and record the event which is bothering you, so you can show that to the dealer along with the log data.
- Get a Bluetooth OBD dongle and buy the 'Torque' app. There's an additional plug in which lets you merge video and the diag data onto the one screen.
- Go out, do some testing and record the event which is bothering you, so you can show that to the dealer along with the log data.
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
We've had one or two 205's with a flaky CKP. They are a ***** to troubleshoot as if the RPM signal drops out momentarily, the car doesn't really think it's an issue, it doesn't set a code right away. We've had the field rep there with a car having a similar issue and even he acknowledged that they don't have a real fix for it, but so far every time we've replaced the sensor it goes away. I think it's just a batch of bad sensors, only been a few cars though.
