w203 engine decode

[oilit]

hi, i had a strange engine behaviour yesterday where it seemed to get its revs wrong whilst maneuvering around a car park and almost dropped to zero revs whilst trying to pull up an incline. Its a 2003 c200k with fmbsh and 141k miles. I have just plugged in a diagnostic tool and just got the following:-

stored error P2029-001 engine rpm implausable
P201c-001 misfire from cylinder 1 (P0301)

check engine MIL light on
a: Off assessor (emission limit) maximal 20 misfires within 1000 rpm
b: Off assessor (KAT arming) maximal 4-35 off assessor within 200 rpm


anybody got any ideas what may have been the root cause?

The car seems to drive fine (I had to drive about 100 miles to get home :-( )

thannks for any insight!

 

[markjay]

I don't know what the problem might be, but the 'misfire on cylinder 1' and 'maximal 20 misfires' messages can't be good, as this sort of thing can damage your cats... so I would get it sorted asap even if the car drives OK. HTH.

 

[BlackC55]

Firstly those codes won't tell you much. It is the live data that you want to be looking at. There seems to be an issue with cylinder 1 for some reason.

They suffer with water ingress on number 1 coil and then it causes missfires.

 

[oilit]

Firstly those codes won't tell you much. It is the live data that you want to be looking at. There seems to be an issue with cylinder 1 for some reason.

They suffer with water ingress on number 1 coil and then it causes missfires.

thanks BlackC55

just run a test on live data and here is an extract...

engine rpm 752
coolant 87 deg c
intake air 40 deg c
air flow 1.89gm/s
intake manifold sensor 37kpaA
ignition angle 6.5
throttle value 1.0%
engine torque 8.0%
fuel inj start bank 1 25%
injection bank 1 -0.8%
bank 1 o2 sensor 1 present
bank 1 o2 sensor 2 present
o2 sensor tension bank 1 sensor 1 0.000v
o2 sensor tension bank 1 sensor 2 0.060v

hope this might help to shed a bit more light!

 

[AndyPCD]

Another thing that can cause this fault code is a split breather hose down the side of the engine next to the kompressor.

Sometimes the misfire on cylinder number one is a little bit of a red herring as i had one last week with the same fault codes.

Iswapped over the coils and plugs etc and the fault was still there also checked the compressions and they were spot on.

So last thing was to check the breather pipe and bingo it had a split in it

 

[oilit]

Another thing that can cause this fault code is a split breather hose down the side of the engine next to the kompressor.

Sometimes the misfire on cylinder number one is a little bit of a red herring as i had one last week with the same fault codes.

Iswapped over the coils and plugs etc and the fault was still there also checked the compressions and they were spot on.

So last thing was to check the breather pipe and bingo it had a split in it

thanks - I will chk the hose, then coil and see where we end up

 

[azaman]

If the breather hose is the same as the C180K engine I have a new, unused hose you can have for peanuts.

 

[oilit]

can somebody give me a clue as to where the breather pipe is - i just had a quick look but have the feeling i need a map !!! (and the haynes manwell was useless!)

 

[BlackC55]

the airbox has to be removed to gain access.

 

[oilit]

the airbox has to be removed to gain access.

Thanks guys, got the airbox off, and there it was - a nice big 1" split down the pipe

also worth seeing that the air filter was filthy - so much for main stealer serving....

So after a lot of cussing have now changed the pipe.

One other question - what are the two round housings either side of the thermostat housing on the front of the engine - I took the electrical connectors off them both (thinking they were camshaft sensors - which haynes suggest they are not!) and noticed that the drivers side has oil inside the electrical connector....

Much appreciated re the pipe