Help - M271 Engine Rough Idle, Misfire Codes P0301-303, P0325 Knock Sensor, P0341 Cam Pos Sensor

[Alan Rodger]

Mercedes C180K - 2006 (W203)
Engine M271
100,000 miles

My C180K will not start and if it does it sounds like a diesel tractor and runs rough. Can anyone help me detect the reason because due to Covid 19 i can't take it to a garage and i need the car to use to shop etc.

It all started the one morning when the car started up fine but had a rough idle. I could rev the engine cleanly but it would idle rough. I took the car on a drive and it was fine on the motorway for 30 miles but it still idled roughly when stationary. I then made the return journey about 2 hours later and the car ran fine again but still had an idle issue. Once i had reached my destination i tried to start the engine again about an hour later and the engine ran really badly and sounded like a diesel tractor so i immediately turned it off. I used my handheld code reader and got teh following codes:

P0301, P0302, P0301, but not P0304 All codes are listed as Cylinder Misfire Detected
P0325 - Knock Sensor 1 Circuit Bank 1 or Single Sensor
P0341 - Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor

I have replaced the Camshaft Position Sensor with a new one thinking that was the issue but the problem still exists

I called the roadside recovery company (AA Ireland) and they called out. He tried to start the engine but couldn't get it started. He took out all of the plugs and visually inspected them and none of them were damp or showed particular signs of wear. He tried to start the car again and he managed to get it started and but it was running really rough. He couldn't identify what the issue was and told me to take it to a garage and get them to stick it on their machine.

I do have very oily camshaft magnets. I took them off and cleaned the oil away. There was a trace of oil on one of the terminals which i have cleaned. I traced the wires back to the ECU and there was a small amount of oil at the end of a lead but i can't be sure if this is the camshaft magnet lead. I have seen online that i can test the magnet by attaching a 12v battery and placing an electrical meter inline to the magnet and then by moving a metal spanner around the magnet i should be able to see if the magnet generates a signal. I haven't done this yet but will try to do it next. I have no idea how to test the leads though so if someone can advise on testing that the leads to the magnet give a signal/volt then i would love to hear from you.

So basically, can anyone help diagnose my non-start and rough idle. I don't want to keep replacing potential problem parts with new ones as i don't have much spare cash following Covid work restrictions.

Thanks in advance for any help you guys can provide

Alan

 

[Blobcat]

Hello and welcome,

The M271 is prone to stretching the cam chain and rounding off the camshaft gears

 

[Alan Rodger]

Hello and welcome,

The M271 is prone to stretching the cam chain and rounding off the camshaft gears

Thanks Blobcat for your response.

Are you suggesting that it may have jumped a tooth on one of the cams? If this is the case, would the engine be ruined by pistons hitting valves and therefore a knackered engine, or is it possible for valves and pistons to have missed each other if it only jumped a single tooth?

 

[Oldspanners]

Mercedes C180K - 2006 (W203)
Engine M271
100,000 miles

My C180K will not start and if it does it sounds like a diesel tractor and runs rough. Can anyone help me detect the reason because due to Covid 19 i can't take it to a garage and i need the car to use to shop etc.

It all started the one morning when the car started up fine but had a rough idle. I could rev the engine cleanly but it would idle rough. I took the car on a drive and it was fine on the motorway for 30 miles but it still idled roughly when stationary. I then made the return journey about 2 hours later and the car ran fine again but still had an idle issue. Once i had reached my destination i tried to start the engine again about an hour later and the engine ran really badly and sounded like a diesel tractor so i immediately turned it off. I used my handheld code reader and got teh following codes:

P0301, P0302, P0301, but not P0304 All codes are listed as Cylinder Misfire Detected
P0325 - Knock Sensor 1 Circuit Bank 1 or Single Sensor
P0341 - Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor

I have replaced the Camshaft Position Sensor with a new one thinking that was the issue but the problem still exists

I called the roadside recovery company (AA Ireland) and they called out. He tried to start the engine but couldn't get it started. He took out all of the plugs and visually inspected them and none of them were damp or showed particular signs of wear. He tried to start the car again and he managed to get it started and but it was running really rough. He couldn't identify what the issue was and told me to take it to a garage and get them to stick it on their machine.

I do have very oily camshaft magnets. I took them off and cleaned the oil away. There was a trace of oil on one of the terminals which i have cleaned. I traced the wires back to the ECU and there was a small amount of oil at the end of a lead but i can't be sure if this is the camshaft magnet lead. I have seen online that i can test the magnet by attaching a 12v battery and placing an electrical meter inline to the magnet and then by moving a metal spanner around the magnet i should be able to see if the magnet generates a signal. I haven't done this yet but will try to do it next. I have no idea how to test the leads though so if someone can advise on testing that the leads to the magnet give a signal/volt then i would love to hear from you.

So basically, can anyone help diagnose my non-start and rough idle. I don't want to keep replacing potential problem parts with new ones as i don't have much spare cash following Covid work restrictions.

Thanks in advance for any help you guys can provide

Alan

If it's making that much noise I'd not start it again until the cam cover has been removed and the chain and cam sprockets checked for wear and timing. Damaging the valves and pistons is a distinct probability.
You won't get rid of the oil in the wiring harness until your change the cam magnets and insert wire blockers, the most oil will collect at the post cat O2 sensor, the lowest position down on the drivers side beside the bell housing.
Good luck.

 

[Blobcat]

Thanks Blobcat for your response.

Are you suggesting that it may have jumped a tooth on one of the cams? If this is the case, would the engine be ruined by pistons hitting valves and therefore a knackered engine, or is it possible for valves and pistons to have missed each other if it only jumped a single tooth?

As per above , I wouldn't be attempting to start it - unfortunately it is an "Interference Engine" so the valves could well have hit the pistons

 

[John Laidlaw]

agreed- it might not just have jumped a tooth so much as displaced it

 

[Alan Rodger]

Okay, sorry for the delay in responding, work has been very busy this week!!

I spent time working on the car at the weekend and managed to access the cam chain - I wish i hadn't!!

As you can see from the images, the inlet cam has moved approximately 3 teeth over. You can see that the cam teeth look very worn, especially where i have marked in yellow. The exhuast cam teeth look okay in my humble oppinion. DO you think the crank teeth will look as good as the exhaust or as bad as the inlet? Also, the timing chain is very tight, hardly any movement when i try to lift the chain off the guide at the top which was a little encouraging!!

I tried putting down a basic endescope in cyclinder 1 and everything seems to be okay. I haven't looked at 2,3 and 4 yet as the video software i was using (VLC) made the video images very slow and delayed which meant it was too difficult to hold still at times to look around. I will try and find a software that works better and try again.

Here's my question - If i was to loosen the tensioner and move the inlet cam back to it's intended position and set the correct tension back to the tensioner, would it be safe to carry out a compression test by turning over the engine. I don't have access to a leak test, nor do i have a local garage i can get the car to. I plan to slowly hand crank the engine first to make sure there is no unusual resistance before i try a compression test. What's your views?

Thanks again and thanks in advance for any replies

 

[star]

No. New chain, sprockets and tensioner before compression test.

 

[John Laidlaw]

oh dear...

 

[mersum1es]

Another victim of MB 'bicycle' chain...

 

[Alan Rodger]

I don't suppose anyone has a copy of the WIS i could beg/steal/borrow do they? I'd love to know what i need to do to take the head off and what the torque settings are when i put it back together along with taking of the crank sprocket for the timing chain

 

[star]

First thing to do is replace the chain and sprockets, you may have been lucky, it’s just on the cusp of bending valves. Why worry about something you may never have to do. You don’t need to fully rebuild it to do compression test, just chain, tensioner and sprockets, leave rest off.

 

[LostKiwi]

As above. Fix the obvious issue then go from there.