patrickarguello

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.

Mike5215

Are the RPMs staying steady during the jolts or surging?

RichardCranium3

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

patrickarguello

Hi Mike,

Thank you for following up. Yes the RPMs remain steady during the jolts. While accelerating hard I stared down at everything looking for a light or a change in RPMs, but nothing.

ManiacGT

I'd hazard a guess at injectors.

Germancar1

Just take it to the dealer.

M

Mike5215

It's been to the dealer. No codes and cannot reproduce.

StanNH

Try a reset in the car by holding down the CD eject button for several seconds. After the reset, try re-establishing your connection.

removedCFGaccount

Really?

Mikey53

Step away from the keyboard Stan.

removedCFGaccount

What's the frequency, Kenneth?

Mike5215

I think he thought he was posting in the thread about Bluetooth connectivity.

janusgrimnitz

hahahaha

patrickarguello

Hahahaha wow.

patrickarguello

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.

removedCFGaccount

Uh, Kenneth, what got replaced?

patrickarguello

The CD player got replaced Peter

removedCFGaccount

Ah, a frequency change....

DBOC205

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.

ItalianJoe1

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.