C203 EML and lumpy idle/revving

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Kes1907

New Member
Joined
Aug 30, 2017
Messages
2
Car
C-Class Coupe 180K
Hi All,

New MB owner and first time poster so please bear with me whilst I get used to a new car and another forum. I am not new to car forums so before cluttering up the board and not being lazy I have already searched but cannot find the answer......wondering if someone can point me in the right direction.

I've just this week bought a Jasper Blue 2003 W203 Coupe C180K. What a great car. Im really pleased with it. I've never had a MB before and this one looks pretty well looked after. Its only on 62K with a full MBSH and until today has driven really well.

Had a bit of an issue on the way into work today. For a long time i was stuck behind some farm traffic on s single carriageway road with loads of on-coming traffic so no chance to overtake. Then as i approached a short section of dual carriageway I pushed hard to get passed whilst I could. It was only a short burst but i did push hard through the rev range in second and third.

Towards the upper end of 3rd the EML light came on and the car hesitated a little. It then didn't run very well.

It was not in limp mode but it was running a little rough with not as much power, certainly not smooth like it normally was.

I drove for about 10 mins until I could pull in safely somewhere and have a look.

I pulled into a petrol service stn and she was idling really lumpy on tick over and slightly lower than normal. Sounded like an old american V8 muscle car but not as cool - more broken. From outside the car when revved a little at standstill the only way i could describe the sound was like there was a large blowing in the exhaust.

I hoped the bonnet and had a look but couldn't see anything obvious off or a-miss.

Was low on fuel anyway (1/4 tank so not enough to pull dirty fuel if the tank is low) so i filled up while there. The car was switched off for about 15 mins.

When I re-started her, the lumpy idle and revving was gone. She was running fine again???

Now I'm left with the EML light still on but the car feels back to normal. Admittedly I haven't dared push it hard through the revs just incase there is a serious problem but I've driven probably about 80 miles since filling up and she feels fine - just the EML on.

I will have the codes read during the week but anyone have any ideas initially??

Edit: forgot to ad, before I bought the car the dealer had the lamba sensor replaced and the garage also fixed an airleak? whilst there, if it helps eliminate something?

Thanks in advance

Kyle
 
Last edited:
Ok so I had the code read and the EML re-set yesterday, car is driving fine and the EML hasn't come back on since.

On the Bosch system we used the only fault code that came back was:

Catalytic converter degradation - misfire cylinder 1.

So this would fit with the lumpy idea and revving....does this mean the cat is on the way out??? Would a faulty cat cause a misfire?

Thanks

Kyle
 

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