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Premium Member
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166 Posts
Discussion Starter #1
Hi Great and Learned MB enthusiasts.

I have a problem with my 1998 SLK230 Kompressor, 89000km.
For a while now it has had a missfire at around 4500revs under load when accelerating and occasionally all through the rev range when cold.
I have a Carsoft 7.4 Diagnostice code reader and the car has shown the following codes:
0300 Off assessor / Off assessor Catalytic Converter noxious = Random Missfire detected
0303 Off assessor Cyl. 3/ Off assessor Catalytic = Missfire cyl 3
B1470 Fuel level indicator sensor B4 - open circuit
B1755 Serial Port K2 from the KLA/TAU panel with the instrument cluster : open circuit

I think i have a bad coil or two. I think the Cat converter may be unservicable as it rattles on startup and within 15 seconds stops rattling.

What are your thoughts?

Any help and advice would be appreciated. R)F)
 

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Hopeless *** owner
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102 Posts
Hi Wheels,

A plugged Cat converter can cause all kinds of issues including what your describing. Although it will usually be across multiple cylinders.
 

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Premium Member 2014 SLK55 AMG
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1,664 Posts
My 230 has been parked up for two weeks, when it went to bed there was nothing wrong with it, took it for a wash yesterday and it's running like a dog! Popping and missing all over! The only thing I've done is remove the roof module .... electrical.
 

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Premium Member
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166 Posts
Discussion Starter #4
I went to check the coil voltage and resistance today and the battery is a bit flat charging overnight and i will take it for a run after checking the coils. Then i will check the tempreature at the cat converters to see if there is a difference between the front and the back (they tell me this is one way of detecting cloged cat's.)
 

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16 Posts
Hi Great and Learned MB enthusiasts.

I have a problem with my 1998 SLK230 Kompressor, 89000km.
For a while now it has had a missfire at around 4500revs under load when accelerating and occasionally all through the rev range when cold.
I have a Carsoft 7.4 Diagnostice code reader and the car has shown the following codes:
0300 Off assessor / Off assessor Catalytic Converter noxious = Random Missfire detected
0303 Off assessor Cyl. 3/ Off assessor Catalytic = Missfire cyl 3
B1470 Fuel level indicator sensor B4 - open circuit
B1755 Serial Port K2 from the KLA/TAU panel with the instrument cluster : open circuit

I think i have a bad coil or two. I think the Cat converter may be unservicable as it rattles on startup and within 15 seconds stops rattling.

What are your thoughts?

Any help and advice would be appreciated. R)F)
read live data when idling, give the engine a bit of throttle and see all readings if they check out.

My slk 230, 1999 gave the same misfire, o2 sensor, you name it... and it turned out to be the MAF- just that the carsoft could not figure that one out due to bad temp resistor in the MAF and I did not have sense to see something was wrong in intake air temp readings...

:mad:
 

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Premium Member 2006 SLK 280-sold
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3,552 Posts
I went to check the coil voltage and resistance today and the battery is a bit flat charging overnight and i will take it for a run after checking the coils.
Just a general comment. I have read that SLK's do not handle marginal batteries well. All kinds of weird things start happening.

Best Wishes,
 

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Another hint; (which you might know but anyway..)

don´t go straight away spending money on a new coil but swap the coils and see if the misfire changes a cylinder.

Also, does your supercharger seem to operate normally?
 
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