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Hello I’m new owner of a c180 engine m271. Just learning about it and could use some advice on steps to a smooth ride and better mpg.
Ive got a 2008 c180 1.8 petrol kompressor sport with 109k miles from the auction as a cat N - (minor rear end damage). I don’t know anything else about the history of the car.
Engine light popped up and I got these reoccurring codes p2188 and p0172 - rich idle bank 1.
The acceleration is laggy at times and the engine is quite loud. It sounds like a loud fan on all the time. Low mpg and just a bit lazy overall. Gear change is lazy with 1st dragging.
My maf reading was 3-7 g/sec at idle and hit 25-30 g/sec when rpm increased.
STFT ranged 14 to -25
LTFT ranged 0 to -15
o2 sensor bank 1 = 1.24 and 3.14
o2 sensor bank 2 = 0 and 0.92
My odb reader is just a cheap one and the readings don’t show consistently throughout the drive for some reason - gives me a couple mins at a time.
I cleaned maf and no change, then found that the pipe going from maf to supercharger wasn’t on properly but fixing that made no change.
I bought the breather hose (with valve)that goes from air intake to engine block. So taken out throttle body, intake, fuel rail and supercharger. I’m thinking to change supercharger oil while it’s out, is it worth it?.
With the sc out I could remove the full 4 part breather hose and valve. The top hose didn’t seem bad, aswell as the one of the other joints hoses underneath but the valve cracked off as I tried to remove it from the pipe and I could see it was hardened and brittle in that part.
new one will be installed.
Breather hose and valve Breather hose and valve
aside from that I realised that the there was oil in the ecu + connectors, not a lot but it was you could see shiney oil residue. I cleaned it with some electrical cleaner but need to go over again because I didn’t want to bend the pins and these still some in the gaps.
checked the camshaft sensors and yep they were oily and a couple drips came out on release, magnets are oily, and a few of the other connectors are oily. Not leaking bad but glazed. I noticed around the back of the engine is covered in oil, any idea what this is? I’m hearing it can be a rear seal?.
back of engine
more oil
Even though it seemed pretty dry from the outside I’m going to check the o2 sensors for oil. I’ve read these can go when the oil gets to them.
Was planning on
1.replacing the magnets
2. Buy camshaft extension leads to prevent further leaks reaching ecu
3. Clean out wire loom, ecu and ecu connectors with cleaner and blow thru with air until oil is gone
4. clean throttle body, air intake and other removed Parts
5. Replace o2 sensors (if necessary) and camshaft sensors? Or will a clean work? Since there are no direct codes for either. if anyone knows the optimal readings I should be aiming for, can you share the info?
I’ve just got a mb scan tool off a friend but I’m going to have to get readings after I do the work and put it all back together again.
This is just quick based on your measurements.
Your LTFT is zero at idle, which should rule out leaking injectors. However, it goes to -15 as you come off idle, so the system is always trying to lean out the mixture by quite a lot. Poor fuel economy means it probably is running rich. The MAF seems to be responding but I don’t have data on what the ranges should be. I haven’t bothered much with STFT as it varies a lot.
You have eliminated exhaust leaks which can invalidate O2 sensor data. After remedial work on the wiring harnesses, magnets, etc, I would be concerned with the O2 sensors and the MAF even though you’re not getting DTCs. Be aware that if the oil actually got into the ECU, it could be compromised. Also, the M271 has been known for deposit buildup on the valves affecting performance.
In the U.S. the C250 M271 EVO was the only I4 model available. There were renegade tuners who would actually change the programming of the ECU to increase output and cause problems as a result. I don’t know if this is applicable to the UK, but since you have no history, I mention it.
Being the owner of a Mercedes without service history may make this more of a resurrection than a repair. Good luck going forward.
For your codes P0172 and P2188, indicating a rich condition on Bank 1, there are several steps you can take to improve your car's performance and fuel efficiency.
Firstly, check the MAF sensor. While your MAF readings seem within a typical range, it's worth cleaning the MAF sensor or replacing it if it's faulty. A dirty or malfunctioning MAF sensor can cause inaccurate readings, leading to a rich fuel mixture.
Your O2 sensor readings appear off, especially on Bank 2. Faulty O2 sensors can send incorrect signals to the engine control unit, causing it to enrich the fuel mixture. Replacing any faulty O2 sensors could help resolve the issue.
Thanks for the advice and opinions guys, i may just buy a new MAF after I clean out the wiring and ecu. But next thing is checking if these o2 sensors.
I’ll have a look at the valve cover for the oil leak probably and do the magnets after along with the rest.
Once everything is cleaned and put back together I’ll get the readings. Hopefully I can get done this week and get some readings on the mb scan tool.
I’ve been busy but was finally able to get the jobs done.
I changed breather hoses and valve got the clip (in red circle) to clip back on with some angled needle nose pliers.
Changed oil in supercharger, cleaned intake manifold and throttle body, injectors etc and re-installed them all.
magnets replaced, waiting for camshaft adapter(pig
tail) cables to arrive. Also waiting for aux belt
Cleaned out the wire harness with electrical cleaner and a blower fan I bought from Amazon as I don’t have access to air compressor right now. I sprayed electrical cleaner and blew some out and wiped off excess until it the fluid coming out was clear. The fan did a good job bringing out hidden oil inside.
checked the o2 bank 1 which didn’t seem bad. When I put everything back together and started up the engine ran a little funny ( some noises) then quietened down. Took it for a drive and it ran great….20 mins later and warning light and codes back.
Started it a few times over the next days and it would do the same strange noise on start up sometimes and also can hear a loud tapping - sounds like the injectors but I don’t remember it sounding like that before.
another thing was some faint smoke was coming out from pre-cat o2 sensor. It calmed down after a while but there was a slight burning smell and that whole area was hot as hell. I didn’t touch anything but you could feel it in the air above it.
FYI the car has always been a bit loud and hot even before any work on it.
It’s when I changed the rocker cover gasket that I saw a lot of oil in cylinder one and a bit in cylinder 2 and the gasket for cylinder 1 was definitely not doing the job.
I used a fluid extractor to get nearly all of the oil I could reach around the plug. I had to take the spark plug out to get the rest clean and I noticed there were bits of gasket around,
I managed to get them all out except on the last cylinder a piece of the rubber gasket (roughly the size of a fingernail clipping) dropped in the hole.
I looked online and most ppl said it should burn off of blow out the exhaust, some said remove the head and go get it out. Any advice?
The rocker cover itself has a little bent part of the plastic at the back where the majority of the leak seems to have taken place. Thinking a replacement might be needed but for now I’m going to see if the new gasket and some gasket maker should lock it in.
Overall at this point think the oil leaking from valve cover and through magnets, and in cylinder is the root. Which Caused oil to get everywhere and contaminate the o2 sensor. Once I’m sure the oil is out of the wires harness and all leaks are sorted I will change the o2 sensor - I’m hoping it’s all good after that. If not I’m thinking possibly injectors. Will change plugs and boots and then give it a run to get the data from mb scan tool. Thanks for the advice!
Oil in the spark plug holes is a typical issue with the M271 engine. My engine was similar to your pictures. New gaskets fixed the problem. Usually, the oil doesn't enter the combustion chambers since the spark plugs are in the way, but I suppose oil could seep around the threads. I had no ignition or running issues, and the spark plugs were bone dry when removed.
Blow compressed air into the cylinder to try and blow the gasket piece out. Or try and suck it out with a shop vac, can even use a piece of hose that fits in the hole and duct tape it to the nozzle of the shop vac.
Oil in the spark plug holes is a typical issue with the M271 engine. My engine was similar to your pictures. New gaskets fixed the problem. Usually, the oil doesn't enter the combustion chambers since the spark plugs are in the way, but I suppose oil could seep around the threads. I had no ignition or running issues, and the spark plugs were bone dry when removed.
1 cylinder spark plug was soaked and 2nd had a little oil. But the rocker/valve cover gasket was done for so that explains it.
Blow compressed air into the cylinder to try and blow the gasket piece out. Or try and suck it out with a shop vac, can even use a piece of hose that fits in the hole and duct tape it to the nozzle of the shop vac.
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