I bought this car last summer, May 04, with the 'check engine' light on, thinking it was something simple since the car ran fine and didn't seem to have any major issues. After I drove it home to Chicago, Il. from Denver, Co. I thought it would be wise to have the dealer check it out. $100's later they told me the MAS ( Mass Airflow Sensor) needed to be replaced, a $350 part. Wow... alot for just a light on my dash.

So I bit the bullet and bought a new one, which I installed myself. Problem solved, so I thought. Six months later I decided to replace the spark plugs since the vehical has 88K on it and I could find no records of this ever being done. After I changed out the spark plugs I started having issues with the car riding rough and the 'Check Engine' going on. I would stop the car and restart it, which only temparely solve this problem.

Basicly the car idles fine but when driven, if I hit the gas hard it seem to stutter and then I get the rough ride issue. This seem to happen more and more as the weeks go on, and now even happend when I am sitting stopped at a traffic light.

I decided to check the engine trouble log with a CarChip which returned a trouble code of, 'P0304' "Cylinder 4 Misfire Detected".

So after reading throught this forums I decided to go back and double check my work, while I was at it I decided to switch the ignistion coils around to see if I could isolate the problem to possiblity one of the coils. So far that didn't work. Same issue and same trouble code.

Any advice would be helpful.

Thanks in advance,
Mike

 

Were the spark plug wires stuck onto the spark plugs when you changed the plugs? Did you have to yank really hard to remove any of them? I broke three or four plug wires when I changed plugs on mine. It caused some serious misfiring.

There's a way to check for broken wires with a multimeter, but I forget exactly how. Age, you know? You want to check the resistance from one end to the other. It should be around 5K to 8K ohms or something like that. I know that someone here will help you with specifics if you don't already know yourself. Anyone?

 

I will pull the wires today and check them to see what the reading is, but from and installation point, the two ignistion coils seems find the springs in there make contact with the spark plugs and the other two spark plug wires 'click' when I installed them.

Let me run the ohm meter and see what I get back.

Thanks Lugnut I'm hoping this is something that simple.

Mike

 

All my wires clicked also. Even the broken ones.

 

I wanted to make sure I wasn't getting ripped off here, but the dealer just quoted me $150 for the set of 2 ignistion wires and 2 ignistion coils. Is this correct, does anyone know if there is a way to buy just the indivisual units themselfs or so I have to buy the whole set.

 

That's probably right.

$65 each for spark plugs wires for mine. Yeah, each. $780 for a set.

 

Well here I am 5 years later and still the same issue with the rough idle while in drive. I've done the following which have not helped:

Replaced the MAF
Replaced the Ignition Coils
Replaced the Ignition wires
Replaced the Spark Plugs
Adjusted the Spark Plug Gap
Cleaned the MAF

I was even following the forum trend started by LORE BENZ: https://mercedesforum.com/forum/show...230+rough+idle

Well I’ve learned to drive around the issue, literally, I mean I can feel when it’ll start to stutter when accelerating so I lay off the gas, I can also prevent it when I’m in drive and standing at a stop light but giving it a little more gas (while holding down the break) or putting it in neutral.

The bottom line is no one seems to know how to fix this. I’m hoping to reopen this issue to see if anyone has made any progress with this.

BTW the 1998 C230 I have now is at 130,000 miles up from the 88,000 when I started complaining about this issue.

 

As I was checking up on the boards I saw last month that a member by the name of 'halfhy' suggested I replace the Cam Shaft Sensor well I'm please to say that fixed about 90% of my issue. The Rough Idle is gone but the acceleration stuttering only occurs in high humid whether.

Overall I'm pleased but still would like to get this issue eliminated completely.

Here is a link to the other post on this topic: https://mercedesforum.com/forum/show...118#post136118

I was able to get an error code 'P0304' "Cylinder 4 Misfire Detected" so I was thinking of replacing the ignition coil for that bank.

Any suggestions?

Today I'm at 139,000 on my 98' C230.