eozomaro

My 2000 SLK230 with 80K miles started driving rough when the engine was cold. Now the problem has become worse. It idles very rough and the Check engine light has come one (hot or cold). I scanned it and got the following codes:

P0170 Fuel Trim Malfunction Bank #1
P0304 Cylinder 4 Misfire
P0110 IAT Sensor Circuit Malfunction
P0410 Secondary Air Injection System Malfunction
P0100 MAF or VAF Circuit Malfunction.

Where on earth do I start ?. BTW, the MAF was replaced recently and have tried other ones with no success.

Please help. With these many codes, the dealership will probably charge an arm and a leg to diagonise it. Could it be one element causing all these codes ?

Racin_fool

one thing you might want to check is the cam adjuster solenoid. I have noticed on alot of the 230 engines (the 111.xxx engines to be exact) that the solenoid starts to internally leak oil past the connector and it soaks up into the engine harness and eventually works its way to the ECU. Take the small cover off the front of the engine and disconnect the plug. The cam adjuster solenoid is the big round metal object bolted to the front of the cylinder head cover with 3 bolts. If you see oil inside the connector, then I would recommend a new engine harness, the solenoid, possibly the ECU and there is an adapter harness between the solenoid and the engine harness that we are installing now to help prevent this.

eozomaro

Sorry, I'm new at this... Where is the engine cover and how do I take off ? Do you have any pics ?

Racin_fool

open the hood and look down at the Valve cover. There is a small plastic section on the front of it that is just clipped on. about 2 inches deep and as wide as the valve cover. You should be able to reach down on the front of it and unclip it and pull it off. After you get it off, you will be able to see what I am talking about.

Also, I wouldn't have any pictures since I don't actually own one of these cars. I just work on them for a living..

eozomaro

I see the cover but no clips. Mine is a 2000 SLK230. Do I have to pry it off from the top or botton with a screw driver ?. It looks like it has a slot on the right hinged to some kind of device and the bottom of the cover has a protrusion which looks like it might be lefted from there. I've tried everything, but still cannot get it off. I hate to break the plastic if I do it wrong. Please help.

Racin_fool

you have to grab the middle of it in the front and just pull it forward hard. They never seem to want to let go but once they do, just pull it up and out of the way..

eozomaro

Hey, thanks a bunch.....I finally got the cover off !. The connector was just dusty and the terminals were clean - no oil inside it. Now what's next ?

Racin_fool

I'll get back to you after I get to work Monday morning and check around for some better information..

eozomaro

Thanks.

BTW, I cleared the codes and drove the care for a while, then scanned it again. This time the only code I get is the P0304. How do I get to the spark plug for cylinder #4 ?

Racin_fool

you need to remove the red cover in the center of the valve cover that says Kompressor on it and then remove the rear spark plug boot so that you can access the spark plug. Be sure to remember how the spark plug wires fit in that valley incase you decide to take them all off at once..

eozomaro

It seems that there is a big black element on top of spark plugs 2 and 4. I guess I have to remove it first ?. If so, do you know what kind of tool I need to remove the 2 bolts holding this device ?

Racin_fool

those black "devices" you are looking at are your coils. If I remember correctly, you will need an E8 or E6 torx socket and a ratchet and then they pull up and off of the spark plugs.

eozomaro

Thanks racin_fool.... I changed spack plug#4 and now the car runs like a charm!. No more ECU codes! I'll change the other 3 plugs later.

Racin_fool

out of curiosity, how many miles are on your car and have the spark plugs ever been changed before?

They are recommended to be changed every 30k miles..

C43AMG

I thought it was 100k ?

Racin_fool

for the 4-cylinder 111 engines, they are recommended at 30k.. That is what it says on the Flex Service Sheets..

C43AMG

Cool , Thanx !

David in OZ

Racin_fool...........I have a 1997 SLK 230K and have noted the electrical connector on the Cam Adj Magnet is moist with oil....but no oil apparent on wire or in loom.........

I have no running problems, but would like your advice re preventive fix

Would you think the adapter harness would be enough of a fix if no oil appears to have tracked into the loom.............

Is GEO25D Starter Line #271 150 27 33 correct for the oil blocking adapter......or are there different connectors on different models?

I have heard that only some later 2000/2001 Magnets leak.....but my Australian 1997 definitely has a leak...........is there any difference in visual appearance or connectors to tell the bad from the good.........

This problem seems to be common and potentially expensive.........do you think all M111 engine owners should consider the anti-oil loom mod?

Thanks

David

merc01

While out for a nice Sunday drive, that dreaded "check Engine " light returned to taunt me some more. This time I recieved the following codes

1. PO173- fuel consumption value for bank 2 exceeded the specified range
(bank 1 identifies the location of cylinder #1, while bank 2
identifies the cylinders on the opposite bank)

2. PO410- The pcm has determined that a malfunction exists in the secondary
air injection system.

This is on a 2001 SLK320 with 65K miles. Thanks for the help on this and thanks Racingfool for your help on my other problem.

Racin_fool

Sorry I didn't see this one earlier. I will make sure tomorrow what the correct part number is for the harness adapter that goes between the magnet/cam adjuster solenoid and the engine harness itself. One thing you wouldn't think of and neither did I until really hearing about this problem is that the wiring harness itself acts like a candle's wick and almost draws the oil through the harness. You would not be able to tell if it was leaking on the outside of the wires or wire loom except by taking the time to unplug the connector and check for oil contamination into the engine harness. If you are sure no further oil has tracked itself back to the engine control module then I would say to take some contact cleaner and spray out the connector, then install the harness adapter and then replace the magnet/solenoid.

If I had one of these engines I would definitely take the time and money to install this harness to prevent the expensive repairs that would follow oil tracking all the way through the system.

Racin_fool

hmm.. I will have to look into that a bit more tomorrow at work. If it was the newer 271 engine then I could tell you exactly what the problem was, but for the 111 engine I am not positive right now. It does sound like you have a vacuum leak somewhere though. Take a flashlight and look around the engine bay to make sure there are no loose vacuum lines or cracked rubber hoses.