Midnight Koop

ok so my dumbass was driving home late last night and was being tailed by a 3.2CL who pulled up next to me at the light. being the genius that i am, i sensed the tension in the air so i raced him at the light and took him off the line and kept my lead until about 50 (must not have been a type s). i was pretty proud of myself...

but it was late and i was shifting with a lazy left foot so my clutch was worked kinda hard... and ever since then when i am sitting idle at a stop light my car randomly shakes. i am so mad at myself for the abuse... but now all i want to do is get it fixed. i sent it in for b-service today and they service adviser said the random shaking could be due to the ethanol in gas these days.... of course i didn't tell him i was riding dirty yesterday when it started to happen.

any ideas on what went wrong or what should be checked if they said there is no problem?

thanks!

C230SportsCoupe

Most likely the problem has been there for awhile, your agreesive driving just triggered the appropriate computer response.

Has your check engine light come on? If so, find a ODB reader and get the code, most likely its a misfire due to a bad spark plug or coil.

Does the problem go away while driving?

Midnight Koop

no error code... the problem isn't noticable while driving.... only noticable when idle. its like someone is randomly pushing the side of my car and making my car shake. i've never noticed it before... just last night and this morning.

sanf

my car was shaking at idle randomly. It went away for a week and then the engine light came on. benz said it was a bad air pump in the front. my car only had 700 miles and it happened after I dropped my car off for another problem. funny how there's alawys more problem after you go into the dealer ya?

I say check around to see if you find any lose connections on the connectors/intake/..etc.

Midnight Koop

thanks... i'll give it a peek under the hood... but im not sure if i'll know what i'm looking for

tee_tz

My car has the same problem, but unfortunately, it's very difficult to determine the problem. You aggressive driving had nothing to do with it, but there are several theories.

When I first had the problem my check engine light came on, and Mercedes replaced the catalytic converter, making the light turn off, but not fully removing the idling. It's worth mentioning that, my car just lost totally power, so at least the cat. converter made my car move again. So I think that may have been part of the problem.

The second theory is something is wrong with the ECU (?) computer, and needs to be reset/flashed because the RPM is not matching the gears or something along those lines.

The third theory, which I understand can be very, very expensive is to replace the engine mounts(?). I'm not sure what this entails, but some people have said replacing them has got rid of the problem.

The other theories revolve around replacing spark plugs and this and that, however, that's not probable because I think your check engine light would turn on.

All in all, I'm still trying to find the problem. Mine doesn't shake so much, it just feel like it's about to turn off, then when I rev, it goes away. So it's something to do with low RPM's that make the car somewhat unstable.


Tee_Tz.

Midnight Koop

thanks tee_tz... i appreciate the explanation. no matter what it is, i am praying they can single it out while its being serviced (under warranty of course!). i am sure that i never noticed it until after driving aggressively last night. i dont think i put the clutch in all the way when i was shifting because it felt pretty rough... and after that is when i really noticed the problem. the problem could have always been there and just amplified last night... who knows?

the dealership is already charging me for realigning my steering wheel (it pulls left) and for remounting my tires which they say are off. so i dont want to spend more than the 150 that they're already charging me for my car thats under warranty still.

alymo

ok the engine mounts are probably not the case..the c class uses the same engine mounts as the s class and they are designed for a v8..in either case they are about 300 CDN to replace at the dealer if you really want to.
another quick fix that is sometimes done by the dealer is raising the ideling about 50 rpm and that usually solves the problem but it works more for continious shaking rather than your case.. the third thing i could suggest is cleaning your MAF sensor (there are a few threads on here that explain how to do this).

tee_tz

Oh really? Okay, I was just throwing out different theories that I've heard. Can you post the link for cleaning the MAF sensor, if it's something one can do them self then I'll start with that and see if that's the problem - in either case, it'll help.

Otherwise, I'm ask the dealer about resetting the idling RPM - is that even possible, why would it be a problem at the current default?

I guess engine mounts are out, good cause that would have been a pricey fix.

Hopefully we solve this problem because I'm sure many people may have encountered the same thing now or later.


Tee_Tz.

alymo

sorry i couldn't find a specific link right now..but search MAF cleaning and you should find it.
the default ideling is not a problem its just on some cars that do vibrate on idle raising the rpm solves it so its just a work arround. now idle vibration could varry from car tyo car based on fuel used and weather and air quality and several other things

alymo

and btw do check your engine mounts in case they were faulty to start with and wore down sooner than normal ...i'm just saying they are pretty tough so they usually don't fail early

tee_tz

No, my engine mounts are most likely fine, it's just someone mentioned that it sounds like an engine mount problem, but maybe not.

I will search for the MAF cleaning process, hopefully that's the problem because it sounds the easiest to do. I will also ask the dealer about rasising the RPM at idling - is there a better way of wording that? Just don't want to ask them and hear. ... ....... .. .. . . what?


Tee_Tz.

darksideprodigy

my car clk 430 had same problem just got it back from dealer it was a combination of bad plugs and wires and my engine mounts were collapsed very expensive fix 860 for plugs and wires and 910 for engine mounts fixed though

Midnight Koop

holy crap... im guessing that isn't something that warranty will cover? i'll find out what the stealership says tomorrow.

alymo

well just tell them someone i know had a similar problem and the dealer suggested that ( true, happened to my friend, although his rough ideling was contineous) see what they say...and yeah we completley forgot about plugs and wires...that could do it too i guess? what's the milage on your car?

C230 Sport Coup

If it shakes, it's misfiring.

How many miles on your car?

Maybe time for plug and coilpacks.
Motor mounts are covered, in fact everything should be if you still have a warranty. I had MM's replaced, plugs, and 1 coil pack under warranty.

Mine's been running rough when it's cold lately, and sputters a bit when starting. I have a new set of plugs to go in, and I'll check the coil packs too, but I replaced 3 of them (one more had gone bad, but it's a 30 dollar part, I replaced them all which the dealer wouldn't likely do so not worth my time to have them go bad one at a time) not long ago, and the other one is about 50K miles old.
I wait till the valve opens (not sure what the hell it is, but you can hear it...takes about a minute) let it warm up, before driving.

Midnight Koop

it has a bout 42k miles... i'm just afraid that the dealership will pull something on me saying that "nothing is wrong with it". and i want to know an appropriate way to respond. would i be out of place to ask them to check more on it? their technicians are the "experts"... so who knows.

C230 Sport Coup

Maybe wait a little while and see if it gets worse?
If it's a coil pack it'll fail, and you'll get a check engine light.
Then you'll actually have a code to read.

FrankW

either it's cyclinder misfiring or collapsed engine mount or your plugs might be loose.

tee_tz

My car has 37,000 miles. I think I will have them check the plugs and coilpacks, maybe they are loose, otherwise I'm guessing they'll know if they need to be replaced. So it seems it can be happening for a couple of reasons.

Engine mounts seems like the most expensive option, therefore, I will leave that assumption to last. Cyclinder misfiring??? That just sounds expensive! Are any of these things covered under warranty?

I'll also wait for midnight kompre's review from the dealership on their dignostics - and then take it to my dealership and yes, tell them that someone had the same problem and it seemed to work.

This is a pretty annoying problem and now happens more often, not something I can easily ignore. I'm having reservations about my car now.

For those who've got this fixed have you ever had a problem with the car since? Once those things were fixed was it instantly better?


Tee_Tz.

FrankW

if ur car's still under warranty they are all covered. just bring it to the dealership and have them check for rough idle.

Midnight Koop

my warranty expires in 2-3 months... so i hope i wont have to wait around for a check engine light to come on. with my lucky it will be the day after my warranty expires

Midnight Koop

just got a call from the dealership and they informed me that there was a vacuum leak in the supercharger. it took them a while to isolate the crack and fix it, but thats what was causing the rough idling. it was covered under warrant.... phew!

i hope that helps any of you with the same problem. tell your dealerships to check for a leaky vacuum for any possible cracks.

off to pick up my car and make sure it rides okay.

later

tee_tz

midnight kompre - Thanks. Okay, that'll be the first thing I'll have them check. How rough is yours shaking -- mine's not terrible like a MACK truck, but it's just slightly and feels like it's about to switch off, but doesn't.

Anyway, I'll reserve an appointment.


Tee_Tz.

Midnight Koop

TT: my rough shaking was very sporatic but nothing like a mack truck either. it felt similar to a jug of milk hitting the walls of my trunk at random.

the good news is that it is completely gone! the replaced vacuum did the trick. i drove around for 15-20 min after i picked up my car and didn't notice a thing.

i hope your car is fixed as easily and under warranty