rough idle

265

Asked by Sep 30, 2011 at 06:15 PM about the 1994 Mercedes-Benz C-Class C 220 Sedan

Question type: Maintenance & Repair

when i am driving it runs perfect but when it is stopped or put it park it runs rough?

43 Answers

545

I had the same prblm, the solution for me was funny, i just put some oil on the ignition parts under the hood. It was just stucking from dust or rust. try that, it could help :)

40 of 40 people found this helpful.
265

i give that a shot this weekend, Thanks.

12 of 12 people found this helpful.
495

its the same problem in my 2002 c200,it caused by the nuetral pooly and the engine fountdation.......

42 of 42 people found this helpful.
265

Is that an easy fix?,

9 of 9 people found this helpful.
495

you have to put arround 12-15 grands for the fix and have to order parts from company.

7 of 7 people found this helpful.
4,995

Rough idling can be cause by a couple of things, vacuum leak somewhere in the intake, a dirty throttle body. ( it has passage ways that allow for idle when the throttle is closed, if those passage ways are dirty it can affect the idle, car might idle too low and even stalls) or it could be just the engine mounts are bad and you are mistaking the extra vibration as a rough idle. I would rule out spark plug or spark plug wires only because the rough running would continue when you are driving or possibly gets worst with additional engine load.

27 of 27 people found this helpful.
4,995

I would not suggest putting oil on your ignition parts

18 of 18 people found this helpful.
545

Yes, Lorne, I really apologize for the website and all readers. I used the word "ignition" instead of "injection" but I said " under the hood" to make it more clear. My english is not very good :( sorry for that, but waht I put oil on is these parts in the picture and the things around (i.e. when you press on the penzine pedal it should come back, but in my case it wasn't), and it really worked for me because there was a lot of dust and rust on them that caused hard moving for the cord. Thank you for correcting my mistake.

14 of 14 people found this helpful.
265

i worked on it over the weekend and i found that the trottle body boot would not get tight and like you said everytime i gave it a little gas i could here a vacum leak. i will start by getting a new boot for the trottle body and i will see if that gets me to pass emissons, you see the problem that i have is that when you turn it up on the test it is dumping to much fuel up top and even though it runs ruff at idle it runs very clean and passed that part of the emissons test. you see thats whats crazey because when you turn it up it runs smooth, go figure!!

5 of 5 people found this helpful.
4,995

Hmmm, so what you're saying is it idles ruff but passed that part of the test and runs smooth off-idle but fails that part because it's running too rich ( too much fuel). If you had a vacuum leak at the throttle body you'll be running lean not rich as you are now. You see with a vacuum leak, unmetered air is getting into the engine without passing through the air mass sensor, therefore the computer can't account for that unmetered air and can't calculate the correct fuel trim hence more air than fuel and the car runs lean. You said you car is running rich ( more fuel than air) so we have to look for things that would make a car run rich. Check for these things 1. Is your car fully warmed up when you take the emissions test? It has to be at normal operational temp. By design most cars are programed to run rich when cold to get the catalytic converter up to proper temp faster 2. Is your oxygen sensor working properly? ( Check your OBDII fault code at pep boys, It might not be enough to turn on the engine check light but might still register a pending fault code) The engine computer uses this sensor to check how much O2 is in the exhaust and adjust the fuel accordingly. if the sensor is bad the computer miscalculates and most likely will inject more fuel than needed ( car runs rich) 3. Dirty injectors ( irregular spray pattern, fuel comes out in a stream instead of a fine atomized spray) that will sure to make the car run ruff and run rich 4. Worn spark plugs or plug wires, but in the absence of hesitation and misfiring under load which you never mentioned as a symptom we can almost rule that out, besides, modern spark plugs are good for 100K miles these days.

20 of 20 people found this helpful.
160

Idling problen on merc 230E.Can anyone help

16 of 16 people found this helpful.
80

I have an '82 SEC that had idle problems for a year and finally got unbearable. I finally found out that the problem was that corrosion had eaten holes in my intake manifold and it was leaking air. This upset the vacuum lines that depend on a vacuum to maintain a steady idle. Check for vacuum leaks with a smoke generator injecting smoke into any vacuum line and see where the smoke comes out. That's a leak that needs to be plugged. Other than that, there is the Idle Control Unit computer and the Idle Control Adjustment Valve, all which control the idle. I replaced both before I found out it was a simple vacuum leak.

2 of 2 people found this helpful.
50

I had the same problem. I changed the spark plugs and the problem was gone.

5 of 5 people found this helpful.
145

i have a 02 mercedes c180 6 speed gear box 2ltr petrol saloon i have it a week and in the morning when you start the car it will start with the first turn but engine loses power for 30-40 seconds and noise coming from under the bonnet but i dont think its the engine but when i drive car its like its driving perfect but today i came back from around 30mile journey and car was started and just started losing power and when i tried to accelerate there was nothin and car just cut out..every time i try to start it it will start and lose power then cut out in the space of a few seconds.. please i need help any answers would be helpful..thanks

14 of 14 people found this helpful.
90

Look for air leaks in the vacuum lines or in the air intake. Few points need to check: the fuel you have used might have been NOT a premium or 91, the spark plugs/ cables are wearing out.

3 of 3 people found this helpful.
90

If you have changed your belt you need to make sure to use the TDC procedure when putting on the new one.

6 of 6 people found this helpful.
50

Hi everyone - I am driving a Mercedes C180 2004 model, at first it only occasionally started misfiring when low revs or stopped at a stop street. The idling sounded very erratic as well. It only got worse during the past year. One Mercedes specialist told be that my cars engine is a gonner and the timing chain and gears were also damaged. Another one told us that our ECU was faulty and then suddenly there was no pressure on the one valve and so the so-called list of difference diagnosis started. It turned out to be the catalytic convertor which was missing and causing all the problems. The previous owner had it removed when replacing the x haust. I found a magnaflow catalytic convertor which also works on the Merc and much cheaper than the Mercedes original. My car is 100% better.

5 of 5 people found this helpful.
240

rough idle in low speeds is usually due to leaking of vacuum lines check and replace the connectors / tubes ( see pic of vacuum line connector of C 180 petrol )

24 of 24 people found this helpful.
80

Mine had holes in the manifold that had to be filled in with JB Weld or something similar. Run smoke into an outlet and see where it comes out. That's the leak.

4 of 4 people found this helpful.
150

For rough idle problem check the fuel pressure regulator (on injection system @ front top of motor) it has a small rubber vacuum line on it, with the engine running; gently pull off the vacuum hose and hold it about 1/4 inch away from nipple. If you see petrol coming from the nipple on the regulator into the vacuum hose - there's your problem! Replace the fuel pressure regulator and it will run like new!

11 of 11 people found this helpful.
280

I have a 2009 c300. My check engine light came on right after I changed the air filters. I have a rough idle, but runs fine on the road. Mass air flow sensor? 02 sensor?

28 of 28 people found this helpful.
85

i have a MB c 180 1996 manual transmision, previously would stall will in gear and while driving, was diagnosed and mmixture was found too rich and idle control in emergecny, the mechanic advised me to replace harness and oxygen sensor first but i feared touching harness, i dealt with oxygen sensor first, it ran well for about one month, after fueling it just started misfirng and stalled, am thinking the harness is messed up, help plez Herbert in kampala,

5 of 5 people found this helpful.
60

help me 2004 c230K changed all mounts, tune up, changed filters still feel vibration when i pull off is that normal...

6 of 6 people found this helpful.
30

I have same problem with my c200 , went to the dealer and said there is a power failer from the ignition to the starter. There key is checked and working well. The car can start only using the earth , still waiting for help. Presently im not using the car. Please help

3 of 3 people found this helpful.
120

I bought a 2005 c240 not long ago. a week later it suddenly cut off when it dropped down into idle at a traffic light.Sometimes it sounded like an old V-8 duel exhaust sitting at a red light, or RPM's were all over the place, would shutter and cut off at slow speed or at stops, if it could idle it would idle high, had to sit with one foot on the brake and the other feathering the gas. Turning on the AC was enough to make it cut off (took me longer to find that out because I'm a windows down kind of person). I took it to a mechanic and they changed the MAF sensor and it ran well for a week or two. The back to same ole crud. I replaced the air filters and the fuel filter myself. Replaced the generic MAF the shop put on with a BOSCH, bought gas at different gas stations. Nothing changed. I was ready to drive it into the river and claim it as stolen, I was beyond over being the owner of a Mercedes. As last resort I must have tried every kind of fuel additive from the chain auto parts store. I figured it couldnt hurt, and made me feel like I was at least still trying. I ended up coming across a bottle of Mr. Gasket Cataclean. At $25 I wasn't sure if I was just letting myself be roped into another "miracle" fluid or if I should be sad that I've come to spending $25 dollars on a bottle of stuff that for all i know could just be big a big bottle of disappointment. Like when you open the bottle you actually hear the bottle say "sucker". You add this stuff when you have 4 gallons left, then drive around 15 miles, then fill back up. I had to drive a week before getting near 4 gallons but I finally got close enough and poured the bottle in. The next day... Runs like a dream (so far perfectly for 5 days - knock on wood) Idles silently at about 4-500 rpms - i keep checking to make sure its still on. No shake or shimmy. No problems at all. I'm completely shocked. Also completely mad that I was made a sucker out of by the mechanics and it was a plastic bottle of miracle fluid that actually fixed my car. Go try this stuff first - it is worth a shot.

8 of 8 people found this helpful.
160

I HAVE MERCEDES C220 ELEGANCE 2002. IN THE MORNING WHEN I START THE CAR DOESN'T WALK AFTER ACCELERATION 3 OR 4 TIME SHE STOP PICKING ACCELERATION AND AFTER PASSING 2 OR 3 MINUTE THERE IS NO PROBLEM ...BUT TODAY WHEN I WAS ON THE ROAD AND STOP THE CAR ON RED SIGN AFTER GREEN LIGHT SHE DOESN'T RUN AND STOP PICKING ACCELERATION ,,,CAN SOMEBODY TELL ME WHAT SHOULD I DO

12 of 12 people found this helpful.
160

SORRY ABOUT MY ENGLISH,,,,,,,,,

4 of 4 people found this helpful.
120

The post I had above the cat cleaner was the temporary answer for me. Turned out the real culprit was my spark plugs. I was firing on 11 out of 12 plugs and the rest were horrible looking.

4 of 4 people found this helpful.
85

#Mirza, have u checked fuel filter and carbon in the actuator/ idle ctrl unit? u may also have to check the plug wires

3 of 3 people found this helpful.
10

Be sure to check your battery. Insufficient amperage/voltage can cause misfire which is more noticeable at idle speed.

1 of 1 people found this helpful.
40

Burn the car to the ground and you won't have any more problems.

3 of 3 people found this helpful.
40

Then have a funeral for the remains, Your problem is now out of sight.

1 of 1 people found this helpful.
20

I have 2 mercedes c230's. Each one had idle problems at around 60,000 to 70.000 miles. I took each mercedes to 2 different mechancs. The conclusion for both mechanics was that the alternator needed to be replaced. After replacing the alternators, the idle went back to normal. It was perfect again.

2 of 2 people found this helpful.
10

was that morning time only or at all times

1 of 1 people found this helpful.
30

With all Merced an alternator is an essential power generator to the motor so whichever problem to trouble shooter is the master key to the battery which is the power store that distributes it via the ignition key then to the other parts where it is required but remember Merced uses ground signals to trigger fuel and spark management so when the alternator decreases power in terms of voltage output then ground dies immediately coz positive is in low supply then the engine stalls so those garages where you took the motors are perfect mechanics I suggest they know Mercedes Benz there good guys but they didn't unveil the secret behind the alternator like I've done it for u keep on with them there good mechanics

3 of 3 people found this helpful.
40

Hi there, I have an X reg Mercedes and it is currently with a garage that haven't identified what is wrong with it. It is hunting big time when stationary i.e. it feels like I am sitting on a child's fairground ride and bobbing up and down! It also turns over for a while when you start it up but always starts. The fault testing is showing no faults apparently

4 of 4 people found this helpful.
30

Good day, i have a Mercedes, c240. Its got a problem of cutting off the engine on its own each time i start it in the morning. However if i briefly pull off the battery terminal and put it back the car starts and runs normally. I put it on the diagnostic machine and there were no faulty codes. My challenge is in the morning and im worried that till when will i be continuing to pull off the battery terminal. Please assist. its a 203 model

3 of 3 people found this helpful.
40

Hi I have a 1995 Mercedes Benz s500 please can you help me to fix it it will run for a little bit it won't Drive good I press gas paddle and it won't drvie please help

2 of 2 people found this helpful.

If you press the gas and its in gear and wont drive the issue is with the tranny. These are complex cars and can be the tranny module

change your fuel pump that's the answer to the problem. I just changed mine in Nigeria and be careful cos it selects fuel pump, just use the original one. thanks..

10

Hi, I have a 2003 220CDI. Engine stops everytime I get to a street light or when I leave the car at idling for over 15 secs. For the rest engine runs fine. I just had oil changed and oil and fuel filters replaced. Any ideas please help.

1 of 1 people found this helpful.

i have a C200 Kompressor 2001 model, automatic, 2ltr petrol. I have had it for a while and if I go on long journeys it would sometimes lose power as I am driving and couldn't rev and would cut out. I took it for a drive last night and turned it off then when I went to restart it it started but I couldn't rev and it lost power and cut out. It is still doing the same this morning so have had to tow it home. Any ideas or help would be greatly appreciated...

I had the same problem with my 2002 180c compressor with 240,000km on the clock. I was stretched timing chain & worn timing sprockets that effected the valve timing. Cost NZ$10k to fix

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