fchen911

My car is acting quite weird recently. The whole car starts to vibrate when the car comes to a complete stop at the traffic light. This problem doesnt happen every single time, but at least 3 times a day. Then the car seems hard to accelerate for 2 seconds after stepping on the gas, and soon start accelerate. The vibrate disappears after stepping on gas too.

Please let me know whats going on if someone here have faced the same problem. Thanks !!

mig888

Check your vacuum lines - quickly, possibly a vacuum leak. Good luck.

flip

icecold911

Hi... Can this be electronic problem? i just called up a mechanic and he said might be electronic problem. If its a vacuum leak, then the car should idle every single time when the car comes to complete stop. This problem is getting quite annoying sometimes.

akbro93704

It could be the engine mounts. Our old E320 used to vibrate very bad at idle as well, turns out the engine mounts were collapsed

EV0LVE

how low is the rpm at idle? it could be that, i'll check mine later and let you know what the normal idle rpm is. a bad spark plug may do that to, maybe you're running on 5 cylinders (or maybe even four). any check engine light?

fchen911

Engine mount can cause the car to idle at complete stop? but it only happens "sometimes" , not everything single time when car stops... and when the car idles, i just step on the gas alittle and the idle disappears...
in addition, when car idles it will get alittle hard to accelerate the car for like 2 seconds ( feel car has no power and not moving ) and it starts running after that 2 seconds... so weird....

fchen911

i think it idles at very normal rpm... 800 to 1000 rpm... i have the rpm running since i have this car brand new... nothing wrong as even the engine light not on... no warning at all showing... so u mean i should change spark plug? my car is a 6 cylinder v6...

EV0LVE

It's not a guarantee but it is one of the cheapest ways to possibly fix it. Vacuum lines could do it too, but goodluck finding the leak. Fuel filter too, if you filled in a debris-filled gasoline. I'm sorry for blabbing here but those are possibilities. goodluck

nlpamg

I don't have a 320, but it happened to me. over 20mph the car would be fine, but at idle and low speeds it would shake and shudder, and the check engine light was on...

I took it to the dealer and they said they just reflashed the ECU and that took care of the problem...

fchen911

Maybe I should take my car to a major service and see if the situation gets any better.

fchen911

I talked to a mechanic yesterday, and he told me that might be electronic problem not mechanical. Like u said, ECU caused your car to idle at complete stop and low speed. There are so many possibilities... sigh....

EV0LVE

I hope a major service does the trick too, and if it doesn't tell them they did it.

SF_Benz

I have the same problem with my c320. When at a stop, the car sometime idles really rough, sometimes it's smooth. THis occurs at completely random times regardless if the car is warmed up or not. I brought it in for service and they replaced the plug wires. My car ran smoothly for about 2 weeks, but then it started to idle rough again. My car is no longer under warranty, so I'm hesitant to bring it in for service again.

mleskovar

Your symptoms are similar to what many had in '01 and '02 cars and the problem was the fuel pump.

srfcty

just got the car back from the dealer yesterday.... the diagnosis they gave for the problem was that the engine cover needed to be replaced... maybe you have the same problem?

fchen911

My car is no longer under warranty too.. thats why i havent send my car in for dealer check. Dont know what to do at this moment...

fchen911

fuel pump? sounds quite accurate. When the engine doesnt get enough fuel pump into it, the car will start shaking as well...
if this is a common problem, will dealer charge me for fixing it???

fchen911

engine cover?? what does the cover has to do with the vibration???

mleskovar

If it's out of warranty they will charge unless you can talk them into doing it for free. Intermittent problems are hard to find and often you expend a lot of time an money searching for the problem. No one will guarantee a first time sure fix and the usual parts they try are coil packs, primary wires, maf, etcs etc. None of which are cheap. Search the forum and you'll find several references to the fuel pump problem with symptoms identical to yours. But that doesn't mean it's the problem!! $160 for the part on the internet and I've seen DIY posted here. You might also try an independent to fix it.

mbz4810

I'm in the industry....

We had a new M class that, SHAKES not vibrate, but shakes left - right like it's gasping for gasoline.... MBUSA bought the car back under CA Lemon Law cuz the dealers dont know what to do.

The fix, if that is what your car is doing is to change the Air Mast Meter around $300 or so and that should solve it.

TruTaing

I have had the same problem, but only ONCE. It has never happened again and it was right after refilling my tank. You guys seem to mention that we should change the fuel pump and/or the fuel filter. What brand would you guys suggest? Are there better/worse fuel pumps/filters? I would imagine they all do roughly the same thing... How often do the fuel filter/pumps need to be replaced?

Thanks!!

mleskovar

If it only happened once I wouldn't do anything. There's a recommended interval for changing the fuel filter in one of your owner's books and the pump should only be changed if it's broken/suspect. The filters and pumps are specialized and there are several manufacturers that provide them to MB...Bosch is a commonly used brand for fuel and electric parts.

CHATMANR

Happened to me...it was 2 broken motor mounts.

SF_Benz

My engine would sporadically idle roughly, then 1 day my check engine light went on and the engine started to run really rough.

The computer code read engine misfire in cyl # 2.

I suspected it was a plug wire or a coil. I brought it into a Mercedes/ BMW mechanic in Palo Alto.

They replaced all the plug wires and spark plugs for $500 and the enginre runs like butta.

MBZ recommends changing the plugs and wires at 100k miles, my car only has 45k miles on it. Oh well, at least my car runs like new again.

MoMocedes

My coupe acts like that to and my check engine light came on two days ago after the car stalled on me after I drove it around for three hours in 97 degree weather. It shakes when its idle or if its in park. I'm assuming its the fuel pump because it smelled like gas after I turned it back on, also when I filled up yesterday the gas overflowed out of the tank.