erin027

I bought a 2010 C300 certified (20k miles) as a gift to my dad for about two months ago and ever since then, we went to the service three times. I had so many problems with it, but there is one issue that they kept saying they couldn't duplicate it.

Whenever the car starts in the morning (in cold engine), after about 5 sec, car shakes a lot for 3-5 sec. It's very noticeable, but the dealer kept saying it's normal that the car shakes in a cold engine.
I really don't think this is a normal.

Any idea what is causing it?
Perhaps, the previous owner used non-premium gas???

HELP! Please!!! I am getting frustrated

++++
Also, this is another issue we found. It doesn't happen all the time, but some times when he goes above 75mph or higher and let goes the gas pedal, speed decreases rapidly. Any idea why?
Thanks!!

jctevere

It is indeed normal. This is because the lifters are activated when it is cold out - keeping your idle RPM's artificially high to warm up the engine and catalytic converters. You will notice that it is up above 1,000 RPM's when you feel this, and then the issue goes away when the lifters settle and the RPM's idle at their normal 750-900 ish range.

As far as the "rapid" decrease in speed, rapid is a subjective thing. Hard for us to say... Perhaps the engine downshifts as you let off the throttle (which slows the car down more) as the car predicts you're wanting to stop or slow down. It could also just be that the car you previously had "coasted" much easier?

erin027

Thanks for the reply.

Two things. The shakiness is not just a small shake. The whole car shakes. Compare to the loaner car it's about 3times. Is it still normal for mercedes?

Also, the speed decrease issue.... it's the point where I almost had an accident.
Does anything has to do with using non-premium gas??

Thanks again!

aMsupp

I don't have any shakiness on cold starts... ever. I've had the car a year and a half and in temperatures around 0 F... sounds messed up.

As far as your deceleration issue... have you mentioned this to the dealer?

Also, was your car a CPO (Certified Pre Owned)? Did you buy it from a MB dealer?

aamirani

Yes, non-premium gas WILL cause the shaking. You MUST use premium gas in a Mercedes or you will run into too many problems.

victort

my car shakes too for like 3-5 seconds. i dont see it as a big deal... it's just trying to warm up

erin027

It's Certified car that I bought two months ago from MB dealer (Fletcher Jones in Newport, CA). It's 2010 C300 with 20,000 milages on it. I mentioned the issue and I am brought the car in four times in last two months with other issues, but they couldn't fix the shakiness and deceleration because they kept saying they couldn't duplicate the issues.

I don't know what else to do. I use premium gas only but I can't do anything if the previous owner used non-premium gas before.

I am considering to see the lawyer if they can't fix this issues.

RLE

This post just flat amazes me. Where on earth did you ever come up with "the lifters are activated when it is cold out?" The lifters "settle?"

You need to delete your entire post since it is technically a fantasy.

Domm

You can search "tcu reset" for the deceleration issue you mentioned.

aMsupp

I might be going out on a limb here... but your "deceleration" issue doesn't happen ALL the time, right? I can honestly say that the car's blinker takes some getting used to because the cruise is set right there above it (where most cars have their blinker). Do you think he may have hit the cruise to set at a certain speed (thinking he was hitting the blinker), then sped up the car? When he releases the gas it will try and go back to what the car's cruise speed was set to, and it will hit the brakes in order to do so (rapid deceleration).

I'm still uncertain about your shakiness on cold starts. But it is still under warranty and may be worth pursuing legal action if they continue to ignore the problem and say they could not replicate it.

erin027

Thank you for your reply.
Yeah, I think I will see the lawyer soon if they can't fix the shakiness.

2006_C350

Any updates on this? My car does the shaking on cold start too.

Glyn M Ruck

The car decelerates rapidly when lifting off because the Torque Converter is locked up. These cars don't free wheel. This is not an old US slush box. Don't lift off if you don't want the car to slow down. TC lockup is for efficiency reasons. These cars run against compression almost like a manual.

The M272 engine should not shake excessively on cold start, high idle, full open loop enriched running. Some of this can depend on just how cold it is & fuel used. i.e summer or winter grade.

However, the M272 uses very soft silicone fluid filled mounts. Some shake is inevitable until stable idle but you should not feel it inside the car.

Don't touch the throttle at cold start. Just crank the car.