t0lerence

HI all, my first time posting and I guess I have come to a point where I really do need some help. I have a W203 2003 C Class Coupe C180k Auto, since I have purchased this car (6 months ago) I have had a few issues, at the moment, I have a few outstanding ones which I am hoping maybe someone can help point me in the right direction?

I noticed that the MPG has always been around the 20mpg for city driving, I am not exactly a harsh driver and was expecting something more around the 26/7mpg range. I have invested in a ODBII reader which gave me a few codes, at the moment the engine managment light is on and shows code P0171 which means Fuel Trim too rich (bank 1) or System too Lean (Bank 1) depending on where you look, from my research it seems that this could be one of the following:

1) faulty or dirty air mass flow sensor
2) vaccum leak
3) o2 sensor

I have previously taken this to a garage and was told to have my o2sensor checked although the garage didn't seem too confident that was the actual problem.

So I thought lets try cleaning the MAF first using this stuff here:

CRC AIR SENSOR CLEAN MASS AIR FLOW CLEANER MAF UK STOCK on eBay (end time 13-Dec-10 17:51:46 GMT) (ebay MAF Cleaner)

problem is, I have no idea where the MAF is, I have taken a few pictures of the engine, maybe someone can point me in the right direction?









I can tell that the car is losing power as well as wasting more fuel than maybe it should be...

To make matters worse, I now seem to be getting white smoke coming out of the exhaust, I thought this was condensation from the catalytic converter at first but looking at other cars, no one else is having this problem, there was never any smoke from my car before..

Help!

Thanks in advance!

tommy

On the cars that I'm more familiar with, white smoke would mean a head gasket had blown; I'm not sure that the same situation is true on Benzes, but I would not think it is a good thing.

We don't have your model in the US, but what you need to do is remove the engine cover to the right of the main engine block. Trace back the air flow from where the intake tube goes to the air filter area, then find the small tube part that has the sensor attached to it. It will be held by banjo bolts on either end; just remove them, unplug the sensor, and the whole MAF tube will come out. Then either clean or replace; here, they're about $220 US. I would think it would be either the MAF or O2 sensor.

I will be replacing mine over this weekend. It's a little PITA to get out, but with a little effort, it will.

t0lerence

I hope its not a head gasket! Its not white white but more greyish smokey with the smell of petrol in it if that makes any sense?

I will try locating the MAF using your guide thanks for that

mtnman82

In the "stickey's" at the top of the forum page click on the "Aftermartket & OEM modifications" thread, then second link under "Engine/Mechanical" is 'M271 $12 hose replacement'. That's the thread you want. Pictures and instructions in there. If you haven't had that $12 hose replaced yet I'd put odds on it. If you search on my threads I started one with similar issues and that's what it wound up being. I get 20~24 mpg in town, depending on tranny mode (W/S). That's strictly city driving with no highway driving mixed in. Does it run rough at idle or stall at stops?

t0lerence

OK found it, I wonder if there was a recall here in the UK for this, I have found the article for the hose, spoke to MB who have said that the part number for this is 271-018-1282 and that a lot of people are buying this, apparently, this current version is suppose to completely cure the problem. Will pick it up after work tomorrow and try install over the weekend. Is it advisable to use the same clips? I ask because they do not have any news ones instock today...

I thought that the mpg in town would be higher?

krasi

MAF ( MASS) seem like a tube. It is after the air filter and have a connection.

krasi

I have the same problem with my C200K. The prise of my MASS is 400euro here that's why I don't replace yet.
Please, write what happen when you replace yours MAF.

pcy

MAF sensor = Mass Air Flow sensor

Glyn M Ruck

P0171 = System too Lean (Bank 1)
P0172 = System too Rich (Bank 1)

Likely causes

1) faulty or dirty mass air flow sensor
2) vaccum leak - check all pipework
3) Faulty upstream O2 sensor that is cycling too slowly
4) Faulty temperature sender unit that is feeding wrong engine temp to the ECU - This usually causes rich running though.
5) oil in the engine harness from leaking cam sensors.

Injectors, purge system etc. can also cause this but is less likely

Firstly clean MAF & check for air leaks in vacuum pipes & breathers. Unplug cam sensors on front of engine & check for oil.

mtnman82

If you pull the air cleaner & MAF out you should be able to see the $12 hose running along the side of the engine block. You might be able to visibly confirm if that's the culprit. One way to check if it's the MAF is simply by pulling the connector to it and running/driving the car. The computer will use default maps to run the car instead of the MAF sensor. If the car runs better with the connector pulled it's the problem (or at least part of it). This is something I should have done before 'blindly' replacing the MAF.

You can use the same clips, but I'd be tempted to replace with standard hose clamps instead. Same with the clip to remove the hose on the other end of the MAF (I replaced this one with a regular hose clamp - a lot easier to work with).

The best I've ever gotten in town is ~24mpg and the best on the hwy is ~32mpg. I thought that was pretty good for a 1.8L 4 banger. I had a 1.6L Acura Integra before this and it didn't get any better gas mileage (and was a dog compared to the c230). The 'sticker' gas mileage (autos.msn.com) is 21-23 mpg in town and 30-31 mpg on the hwy.

Good luck with it! Please report back and let us know how it goes.

PS - you also definitely also want to check the cam sensors as Glyn suggests above - make sure there is no oil leaking form them.

t0lerence

Hi guys, just an update to this as I have finally found some time to do this, unfortunately, it was something like 2degrees Celsius outside!

Anyway, this actually took me 2 attempts as I didn't have the correct tool. Found out reading up in the other thread that you don't need an E10 invert, instead just use a 8mm Hex socket piece, which i noticed it sooner!

Anyway, followed the tutorial and eventually (had to hacksaw/ rip out with long nose pliers the tube part). I check the actual $12 hose and it actually seemed fine, i took off the close part and no problems, i used my fingers to feel around the other part and from what I could see seemed ok although not 100% as i couldn't get my fingers in

Also, I was trying to clean the MAF as I bought some CRC Maf cleaner, but I just couldn't for the life of it work out how to get it off? It seemed to be connected in the back/bottom to some sort of pipe. I wasn't sure how to take it off or put it back on so I left it. Any advice on this?

Also, what if I was to clean that MAF section from inside the air throttle box (where the air filter is)? Would that be safe? It would be a hell of a lot easier?

@Glyn - i checked the section that you mentioned in the picture and they both clip off and looked fine, no signs of oil on them, where would oil be on this?

I tell you what I did find dodgy was the large grey pipe that connects to the air throttle box, i have used aluminium foil to stick it back down with lots of layers to reinforce it. Unfortunately, I was forced into buying some premium oil (regular out of stock) which doesn't really give me a good indication of whether this has been fixed or not.

I have attached pics of this

I have noticed that the white smoke coming from the exhaust is still quite bad

I have uploaded the video onto imageshack as follows:

http://img163.imageshack.us/img163/9897/sa8.mp4

Any advise guys?

Thanks in advance!

Glyn M Ruck

Good news - No oil in the cam sensor plugs. The "white smoke" looks like steam to me. If it was that cold outdoors - this would seem normal to me. What does it do fully warmed up on a warm day?

I'm not used to working on the M271 but you can clean the MAF in place. As long as you can access the hot wire filament.

Cleaning the MAF is the next step. You seem pretty confident that you don't have any vacuum leaks. So get that MAF cleaned up & let's go from there. That inlet pipe across the front needs replacement but won't cause this problem. It's pre aircleaner.

t0lerence

@Glyn M Ruck

Good news - No oil in the cam sensor plugs.
- Glad to hear that!


The "white smoke" looks like steam to me. If it was that cold outdoors - this would seem normal to me. What does it do fully warmed up on a warm day?

- To be fair, this has just started recently, its around 1-4 degrees Celsius in the UK at the moment although this was not showing during the warmer days. Saying that, i have looked at many other similar cars, none are showing this steam coming out...


I'm not used to working on the M271 but you can clean the MAF in place. As long as you can access the hot wire filament.

- In your attached diagram, I can get to the black mesh part of part 10, Im just wondering if it will cause any problems if the CRC spray goes down that vertical tube thing?


Cleaning the MAF is the next step. You seem pretty confident that you don't have any vacuum leaks.

- If by vacuum leak you are reffering to the $12 hose then I guess so, it looks ok, can't see the further part though, with my fingers I didn't feel any tears. Was there any other parts I should of checked?

So get that MAF cleaned up & let's go from there.

- OK as long as you are sure it won't damage anything lol, i will do it when I have a chance

That inlet pipe across the front needs replacement but won't cause this problem. It's pre aircleaner.

- OK will have to find out how much this will cost, but because its been patched up for now, is this imperative to change soon?

What about the air flter? Should I consider changing that? It looked ok, can this be cleaned with a Vacuum cleaner or anything like that?

Many thanks Glyn!

Glyn M Ruck

The MAF cleaner will evapourate pretty quickly. You can't do any harm. It would be better to remove the MAF but if you are not going to then don't try & restart the car for an hour after you have sprayed the MAF. You might suffer a large backfire. I can assure you that the lazy dealers don't take them off unless they have to.

Glyn M Ruck

BTW - your fuel consumption is high. People here forget that you are talking Imperial Gallons - not weedy American ones.

Are you loosing any brake fluid? Could have a booster leak.
Are you using any coolant?

Get someone to check your coolant for combustion by-products. You get little kits that change colour if they are present. This would be a guide to a blown head gasket.

t0lerence

Will definitely have a go at the MAF in the coming weekend!

The fuel consumption is definitely waaay too high, I have felt that since I purchased the car, so its not my imagination then!

- Are you loosing any brake fluid? Could have a booster leak.

Not that I am aware of, how would I check this?

- Are you using any coolant?

I haven't added anything in myself no, what should I be using? Something like Anti freeze?

- Get someone to check your coolant for combustion by-products. You get little kits that change colour if they are present. This would be a guide to a blown head gasket.

Oh shoot! I checked the engine oil and it seems fine, in previous cars I have had, I was lead to believe tat white mossy stuff inside the engine section usually represents a blown head gasket? Can you point me in the direction of what I am looking for? I can then try find teh UK equivalent.

My luck with my cars grrrrrr

t0lerence

Hi guys, just an update, I finally managed to get around to opening up the air filter section and giving the MAF a good old spraying down! (See pics), left for around an hour and a half for it to dry up and took her for a spin and I am pleased to say that its definitely improved!

Firstly, the smoke and fumes from the exhaust have practically disappeared, the little left is condensation (around 5 degrees yesterday), also the petrol smell in the exhaust is no longer present. The power performance of the car doesn't feel like its changed however, the MPG indicators where before would drop from 32 down to 20 in 3 minutes or so has stabilised. It was average between 24-26MPG yesterday, I guess I need to test this for a few days using like for like petrol and similar driving environments as I was doing a combination of city and dual carriage way driving.

I have attached a small video of what the air filter currently looks like and am wondering if it looks like it needs to be changed as I have no idea what colour a new one starts off.

http://img593.imageshack.us/img593/635/189.mp4

The other thing I am wondering about at the moment is the fact that I only managed to spray the MAF with it connected without taking it out. I am not certain if it was thoroughly cleaned as from the front, there seems to be multiple layers of fine grids designed to prevent large bits and pieces flowing into the car. Should I bother having someone taking this out and cleaning it properly?

Finally, I cleared the ECM light and am waiting to see if it pops up again, fingers crossed it won't!

I am also now started to wonder if the last guy actually did service the car like he told me or if was making it up. Car is reporting that it should be done in 3000 miles, I'm thinking maybe I should do it now?

Glyn M Ruck

I think you should remove the MAF & clean it thoroughly.

Glyn M Ruck

Air filter is not too bad.

t0lerence

I may have to find someone to do this for me, its the part no 40 that i couldn't work out how to take off and i didn't want to take a chance on screwing it up just in case... When I do it though, I will have that $12 hose changed in one go I guess

t0lerence

OK an update on this guys, sadly, it improved MPG lasted a few days then plumetted down to around 15MPG (could be the very cold weather?) and now has gone back to the 20-21MPG average, I guess I will definitely have to take the MAF out and get it cleaned thoroughly...

Any other ideas guys?

Thanks in advance!

Glyn M Ruck

Has the CEL light come back on?

I would sort out that MAF first. Clean or replace.

Try unplugging the MAF & forcing the car to run on a default ECU map when driving. It will not give you perfect fuel trim but if it runs better unplugged it will be another pointer that the MAF is messing around.

t0lerence

NO the light has stayed off, where as before when I thought the problem was fixed, I could not smell anything in the fumes from the exhaust, now it has the smell of petrol as it did previously.

How do you just unplug the MAF? Is there a way to disconnect a part or something?

Glyn M Ruck

There are wires running to a plug on the MAF - just unplug it.

t0lerence

When i was trying to take the MAF off, I think there was a socket type wire that was on teh back that connects to teh ECU i think, would that be the one? DO you remember roughly how many of the cables to take off?

https://mbworld.org/forums/attachmen...ent-hose04.jpg

In this image, is it just the top Green arrow wire I take off? Also leaving testing this without this cable for some hours, would that be a good indication? I shooting off in 15 minutes on a long dive, i guess it will be a good indication