w211 high co and low lambda

[gn1459]

hi guys
i am new to this so please excuse me if i mess up.
i have a problem with my 2003 mercedes w211 e200 1.8 kompressor.
it failed its nct test showing high co (aprox 3.50) and low lambda (aprox 90) meaning rich mixture.
i borrowed a friends same year and model car with good emission readings and swapped over both 02 sensors. air flow sensor. map sensor. temp sensor . throttle body.cat.the pipe under the air box and kompressor. but still the same. i sent the car to a garage(a friend) to see if he could repair it but when i got it back it was running worse it turned out the timing chain had jumped some teeth!!!!!, i thought that this could have been the problem all along but i got the car back today with chain repaired and the car running like a watch (as it had been all along) but the emissions are still the same. i am a retired mechanic used to working on older cars this problem has me baffled. i have read posts on this forum and see you guys know your stuff about mercs.
i would be very grateful if anyone could shed some light on this.

 

[Steve@Avantgarde]

These engines also burn out the exhaust valves there are modified valves, springs, seats and injectors to cure this issue.

Do you have any fault codes stored?

Have a search through the threads on the forum as someone else was having issues with a 271 engine with high emmisions I will see if I can find it as there was some useful info there.

Alex Crow was the indie dealing with it and he may have posted his findings.

 

[Steve@Avantgarde]

http://forums.mercedesclub.org.uk/showthread.php?t=90720&highlight=emmisions

Take a look at this, it might be useful.

 

[Alex Crow]

Well, this is a popular topic at the minute!!

We have recently had a couple of threads just the same as this, with the 271 engine that you have.
First thing is first - have you got any signs of oil contamination of the wiring loom?
If you have not, next question is what fault codes are being generated, and have you tried resetting the self adaptation.
If you have no oil in the loom, the self adaptation and codes have been reset and you have tried all those parts (and cam timing is now correct), the next step might be to get a newer software version flashed into the ECU.

 

[mobeyone]

If oil is found in the wiring loom, what's required to fix this? And at what cost?

 

[gn1459]

high co and low lambda

thanks for all your help and advice.
I wiped all codes as there were too many as a result of broken t/chain and no light or codes have shown since. emissions remain : co 3.48 --lambda 90.
this car was with an ecu repair place with remapping in mind but no success.
i have checked the loom and found very slight amount of oil coming from the left cam sensor so i cut open the loom protection all the way around, through to the ecu and lambda sensors and found no oil at these joints. i cleaned them all with no result. i have full garage facilities at my disposal, so with the car connected to the gas analyser i pulled a connector on the loom harness going to ??? not sure yet ! but it goes down low on the front left of the engine. i am assuming it is around the kompressor somewhere. and the co reading went down and lambda came up to there correct readings. the readings with this plug pulled are perfect at idle but go high again at 2800rpm.this is the only action that has made a difference to the readings.
it was getting late so i had to leave it but i intend to strip the whole lot out tomorrow and find where this is going.
i had a long conversation with the foreman of a very large mercedes dealership and he assures me that i am not going to find the fault as this fault is a dealership nightmare that in most cases they have not resolved.
however i hate a car beating me, this is driving me nuts so i am going to leave the car in the workshop bay connected to the gas tester and stay on this for as long as it takes so any guiding info or direction would be gratefully received. the battle continues.
Thanks

 

[Steve@Avantgarde]

Looking at the info on the last thread I would have a dealer or indie flash the engine ECU to basic settings and perform a software update. Then go from there.

 

[Alex Crow]

From this further info I definately think the software update is the way forward. Alternatively erase self adaptation and go for the long drive of variable speeds with at least 15 mins idling afterwards WITHOUT turning ignition off at any point.