M271 C180k Very rough idle

[Wilko203]

Hey folks,
New to the forum so forgive any ignorance. I've been pulling my hair out for the past week and desperate for assistance.

I bought a W203 C180k M271 and have ran it flawlessly for 6 months. My MAF has been unplugged (as is faulty) the entire time and gives me an extra 3-4 mpg and car was running smoothly.

About 3 weeks ago, just after starting it would idle roughly for about 5 seconds then become normal and I was about to service it with my local mech.

I changed the suspension over to FK street coilovers and drove up to my house again. Fine no problems

Went to sleep and next morning the idle was absolutely terrible. Being an automatic it was undriveable.

It settles itself to idlle on regular jumps between 700 and 1000 in 4/4 time.


What I have done to try and remedy the problem

Replace Crank Breather hose with a temporary large and small hose (sealed) (common fault)
Replaced Camshaft Actuator (a and b) They did have a little oil in the connections
Replaced Camshaft Sensor (which brought up fault so put back in original)


What I have Ordered
New fuel filter (General Service)
New MAF (To get rid of EML)
New coilpack
New spark plugs (General Service)


I can run diagnostics through Torque pro so can read fault codes and get some readings

Current minor faults
p200a (can't find info)
p200b (can't find info)


Has anybody had this issue, would a vacuum leak cause such a big but regular variation?

I can run a smoke test tonight, if so, what vacuum pipe would make a good smoke input)



I'd rather do what I can before I have to fork out for my mechanic to chase his tail.

Any suggestions are welcome and I look forward to having an active contribution on the forums.

(Any vacuum diagrams would also be appreciated)

 

[Terry_]

I think it's best to whip off the valve cover and check the timing marks. You may have air leaks but I would certainly do this first

 

[Wilko203]

Another minor fault comes up at "p2054 Reductant injector circuit low bank1 unit2". Would it be worth changing an injector? (I have spare one). Is that the correct reference? If so, which one?

 

[Wilko203]

Before I go to any more effort in stripping the valve cover off, it can rev ok , it wont idle. Sure if my timing was off it wouldn't rev. When I go to run fuel status on diagnostics it reads o2 sensor closed circuit. Would a faulty o2 sensor cause such a rough idle?

I'm finished firing money into this car and frankly, finished with Mercedes but I'd appreciate the help if it's something simple before I go and sell it for a fraction of it's worth