Misfire Cold Engine
Thread Starter
Newbie
Joined: Aug 2024
Posts: 5
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Mercedes Benz w204 C250
Misfire Cold Engine
Good evening, dear users.
I have been trying to fix my car's problem nearly three months. However, It does not fix. I will really appreciate who helps me about my problem.
I have a misfire when it is in cold engine/start. However, when I am waiting to the engine's temperature comes to the 90 degree, i turned off car and then turn on it fixed the misfire. When it is in the current mod of the misfiring, when i am pushing the gas pedal, the car does not feel the gas pedal. It shows the problem occurs in the Cylinder 2.
I have changed all of the spark plugs, fuel injectors(only cylinder 2 - I just take fuel injector from cylinder 4 and put the second cylinder to check that is the problem is from fuel injector or not), ECU and other electrical components. However, it does not fix.
One of the Mechanical, put the camera to my engine and told that three of the cylinders are oily. He said that, you have to change all of the four fuel injectors. I dont know what I have to do in this problem ...
What are the things that I have to change for that? Maybe the problem can be from the engine ... I really need your help, mercedes bros.
I have been trying to fix my car's problem nearly three months. However, It does not fix. I will really appreciate who helps me about my problem.
I have a misfire when it is in cold engine/start. However, when I am waiting to the engine's temperature comes to the 90 degree, i turned off car and then turn on it fixed the misfire. When it is in the current mod of the misfiring, when i am pushing the gas pedal, the car does not feel the gas pedal. It shows the problem occurs in the Cylinder 2.
I have changed all of the spark plugs, fuel injectors(only cylinder 2 - I just take fuel injector from cylinder 4 and put the second cylinder to check that is the problem is from fuel injector or not), ECU and other electrical components. However, it does not fix.
One of the Mechanical, put the camera to my engine and told that three of the cylinders are oily. He said that, you have to change all of the four fuel injectors. I dont know what I have to do in this problem ...
What are the things that I have to change for that? Maybe the problem can be from the engine ... I really need your help, mercedes bros.
MBWorld Fanatic!
Joined: Aug 2023
Posts: 3,879
Likes: 1,201
From: MA Coast
W204 2010 C300 4matic Sport M272
Which engine do you have, the M271?
So you scanned the car and its showing misfire in cyl #2.
You replaced the spark plugs and you swapped the cyl #2 fuel injector with cyl #4 fuel injector, scanned the car and still getting misfire in cyl #2?
Also there is oil in 3 of the 4 cylinders?
I'm speculating maybe the valve cover is leaking oil.
So you scanned the car and its showing misfire in cyl #2.
You replaced the spark plugs and you swapped the cyl #2 fuel injector with cyl #4 fuel injector, scanned the car and still getting misfire in cyl #2?
Also there is oil in 3 of the 4 cylinders?
I'm speculating maybe the valve cover is leaking oil.
Member
Joined: Dec 2023
Posts: 217
Likes: 74
From: TN
2013 w204 c250 coupe & 2001 Dodge Ram 2500 24v Cummins
Good evening, dear users.
I have been trying to fix my car's problem nearly three months. However, It does not fix. I will really appreciate who helps me about my problem.
I have a misfire when it is in cold engine/start. However, when I am waiting to the engine's temperature comes to the 90 degree, i turned off car and then turn on it fixed the misfire. When it is in the current mod of the misfiring, when i am pushing the gas pedal, the car does not feel the gas pedal. It shows the problem occurs in the Cylinder 2.
I have changed all of the spark plugs, fuel injectors(only cylinder 2 - I just take fuel injector from cylinder 4 and put the second cylinder to check that is the problem is from fuel injector or not), ECU and other electrical components. However, it does not fix.
One of the Mechanical, put the camera to my engine and told that three of the cylinders are oily. He said that, you have to change all of the four fuel injectors. I dont know what I have to do in this problem ...
What are the things that I have to change for that? Maybe the problem can be from the engine ... I really need your help, mercedes bros.
I have been trying to fix my car's problem nearly three months. However, It does not fix. I will really appreciate who helps me about my problem.
I have a misfire when it is in cold engine/start. However, when I am waiting to the engine's temperature comes to the 90 degree, i turned off car and then turn on it fixed the misfire. When it is in the current mod of the misfiring, when i am pushing the gas pedal, the car does not feel the gas pedal. It shows the problem occurs in the Cylinder 2.
I have changed all of the spark plugs, fuel injectors(only cylinder 2 - I just take fuel injector from cylinder 4 and put the second cylinder to check that is the problem is from fuel injector or not), ECU and other electrical components. However, it does not fix.
One of the Mechanical, put the camera to my engine and told that three of the cylinders are oily. He said that, you have to change all of the four fuel injectors. I dont know what I have to do in this problem ...
What are the things that I have to change for that? Maybe the problem can be from the engine ... I really need your help, mercedes bros.
I am with both bv9900 and timc300. Need to get a good scan tool on the car. AND a leaking valve cover is a good suspect for causing mis fires if oil is leaking onto the spark plug. Based on your profile, you have a c250 which is the m271evo engine. There is individual gaskets that go around each spark plug on the valve cover.
I had a misfire when I purchased my c250. Did a full ignition service and no more misfires. Check all your electrical connections going to the ignition coils.
keep us posted!
ant
Member
Joined: Dec 2023
Posts: 217
Likes: 74
From: TN
2013 w204 c250 coupe & 2001 Dodge Ram 2500 24v Cummins
[QUOTE=FM099;9025780]the oil is in the 1,2 and third one. not fourth. what i do you speculating also? is it can be from the head gasket?[/QUOTE
@FM099 - hey if you are getting oil in 1,2, and 3 spark plugs there is a good chance your valve cover gasket has failed and needs to be replaced. There are individual gaskets that go around each spark plug on the valve cover. Those have likely failed.
Do you have any history of maintenance and oil changes on the car? If not, my suggestion would be to replace the valve cover with a new one. Get a OEM Mercedes valve cover. I purchased mine from the local MB dealership and it came with the gaskets pre installed.
There is a high pressure PCV system and check valve built into the valve cover that can get clogged with sludge and build up if the oil changes were not done Regularly.
there is a video on my YouTube channel showing the inside of the valve cover.
I would also do ignition coils but that is just me !
ant
@FM099 - hey if you are getting oil in 1,2, and 3 spark plugs there is a good chance your valve cover gasket has failed and needs to be replaced. There are individual gaskets that go around each spark plug on the valve cover. Those have likely failed.
Do you have any history of maintenance and oil changes on the car? If not, my suggestion would be to replace the valve cover with a new one. Get a OEM Mercedes valve cover. I purchased mine from the local MB dealership and it came with the gaskets pre installed.
There is a high pressure PCV system and check valve built into the valve cover that can get clogged with sludge and build up if the oil changes were not done Regularly.
there is a video on my YouTube channel showing the inside of the valve cover.
I would also do ignition coils but that is just me !
ant
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Thread Starter
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Joined: Aug 2024
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Mercedes Benz w204 C250
I dont really get that, could you please give me an order way of the - which can be possibility of the problem? So , i can start from the cheapest one to the expensive one. I would like to mention it again, it just only doing cold engine - when engine is not cold, there is no misfire - however, power of the engine is significantly reduced.
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Joined: Nov 2016
Posts: 7,847
Likes: 3,499
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
When you first start the car, is there any smoke from the exhaust? Is the car hard to start?
As @antboii and @TimC300 have stated, you may have a leaky valve cover gasket that allow oil to infiltrate the cylinders overnight. You should see excess smoke from the exhaust when starting. But I would not think that would cause loss of power once warmed up. Replacing the valve cover gasket is probably the next cheapest test. Another test you could do is a cylinder compression and leak down test. Search YouTube to see how that is done.
As @antboii and @TimC300 have stated, you may have a leaky valve cover gasket that allow oil to infiltrate the cylinders overnight. You should see excess smoke from the exhaust when starting. But I would not think that would cause loss of power once warmed up. Replacing the valve cover gasket is probably the next cheapest test. Another test you could do is a cylinder compression and leak down test. Search YouTube to see how that is done.
Member
Joined: Jun 2024
Posts: 191
Likes: 58
E320
I’ve seen this issue before, and it can be quite the headache, especially with the W204. From what you've described, it sounds like you might be dealing with a couple of potential culprits. The oily cylinders could indicate a problem with the valve seals or piston rings, allowing oil to seep into the combustion chamber, which can cause misfiring when the engine is cold. Additionally, since you've already replaced the spark plugs and tested the fuel injector, it might be worth checking the ignition coils as they can also lead to misfires, particularly if they are failing under cold conditions.
If the issue persists and you're looking for a comprehensive diagnosis, I highly recommend running a full system scan. The youcanic full system scanner works exceptionally well on these models and can help pinpoint any underlying faults that may not be immediately obvious. Xentry is another solid option, but it does have a steeper learning curve. Hopefully, with a little more troubleshooting, you'll have your C250 running smoothly again—after all, we all know how temperamental these German machines can be!
If the issue persists and you're looking for a comprehensive diagnosis, I highly recommend running a full system scan. The youcanic full system scanner works exceptionally well on these models and can help pinpoint any underlying faults that may not be immediately obvious. Xentry is another solid option, but it does have a steeper learning curve. Hopefully, with a little more troubleshooting, you'll have your C250 running smoothly again—after all, we all know how temperamental these German machines can be!
Joined: Nov 2016
Posts: 7,847
Likes: 3,499
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
I’ve seen this issue before, and it can be quite the headache, especially with the W204. From what you've described, it sounds like you might be dealing with a couple of potential culprits. The oily cylinders could indicate a problem with the valve seals or piston rings, allowing oil to seep into the combustion chamber, which can cause misfiring when the engine is cold.
