Hi eveyone, I have a question.I have2003 mercedes C230 kompressor sedan.I am getting an error for first cylinder misfire and manifold absolute pressure/barometric pressure circuit high input. Is the first cylinder locates toward the windshield or toward the front of the vehicle? Is it necessary to replace the ignition coil or what should i do from here? I just replace all 4 spark plugs, new air filter, 2 newO2 sensors, the up and down stream and a new mass air flow meter.
Thanks in advance for any advices.

 

No. 1 is towards the front of the vehicle.

Try swapping plug / lead / coil pack (depends on engine type etc) between cylinders to see if DTC moves to another cylinder. This can save you a lot of expense for a little effort.

A misfire maybe nothing to do with the electrics.
It could be fuel i.e. Injector. Same opportunity to swap components exists.

Of course make sure you cancel the existing No.1 DTC.

Stuart

 

Help needed to fix 2001 ML430 that is misfiring. I have already replaced the MAF (mass flow sensor), the CPS (crankshaft position sensor) and the 16 Platinum 2+ spark plugs with16 Bosch 4+ platiunum plugs and it still is misfiring. The plugs are wet but it doesn't seem to be getting enough air. Bigboy1

 

ML430. Thought we were discussing C230K?

Step 1.

Get the codes read and come back.

Stuart.

 

Stuart,
I am Bigboy1's wife and I am the one who submitted a request for help. He is still having problems solving the misfiring of the cylinders. Besides changing the MAF sensor, crankshaft position sensor and 16 spark plugs, he purchased the electric throttle actuator and the pedal valve sensor from the dealer yesterday and it is still having problems. Today he wants to unplug the battery so that the computer will reboot as this is what I often do with my computer when it is not acting properly. Is there a particular time when you might be able to have a dialogue with him about his 2001 ML430?
Bigboy1's wife

 

6.00am UK time I'm usually on line.

As I have already stated the starting point is what codes are stored?

Disconnecting the battery will reset the computer but that doesn't always work and if you don't have your (Correct) radio code you will end up with no radio!!

maybe I will hear fom you tomorrow.

Stuart.

 

The codes are 300, 301, 302, 335, 170 and 173

 

Hi,

6.00 AM UK time. Not 6.00 PM

However I just happen to be around to reply.

P0300/301/302 are all misfire. Random, Cyl 1, Cyl 2. OK this is in line with your symptoms.

P0335 Crankshaft Positon Sensor CIRCUIT malfunction. Likely a faulty sensor. The CPS determines the position when the spark occurs. This could be the problem.

P0170/3 Classic signature for the MAF requiring cleaning or better still replacing just to be sure. Usually occurs circa 70k miles.

Problem is you state that your husband has already changed the MAF, Cranksensor and plugs etc so it makes where next more difficult.

However, lets look at how the problem manifests itself.

CEL ON?, misfire at idle, hard acceleration or what.
Service history?
mileage etc. More info please.

Next. Where did the new MAF come from? MB genuine (new) spare or from some un-warranted outlet / secondhand / ebay. Subject to being a genuine neqw MB part (in a sealed hologrammed box) can your husband be sure the electrical connection has been made correctly and that no corrosion was present in the connector.

Can your husband also be sure that the MAF body is correctly assembled? The gasket which holds the MAF body to the inlet manifold has a "tiot" on it to locate it. If this is in the wrong position the air inlet can leak air which will upset the tune and lead to misfire.

Subject to your feedback on this request I will advise "What next".

Need to be 100% sure that the MAF is OK before proceeding.

I assume that the original DTC codes were cleared electronically. If not then it takes a number of driving cycles before the CEL will go off of its own accord assuming the fault has been rectified. If cleared electronically how long /what conditions does it take to come back on. Hard acceleration? What happens if you clear the DTC's and drive with the MAF DISCONNECTED.

Stuart.