[rp.merc.c240]

Hello,

I have a 2002 C240 and I've recently had an issue while driving. I've read similar posts to this one but someone always writes their own issues that are different from this matter.

Basically what happens is while driving, no matter what speed (fast or slow) and whether I'm accelerating or just sitting at idle. It feels like the engine slowly begins to lose power, sputters and finally stalls. There are never any notifications on the dash or any signs of it beginning to fail. This typically happens when I'm slowing down at an intersection or just driving slower in traffic. I've noticed that once I'm stopped and the engine begins to lose power and begins to sputter that the rpm's are still idling normally at around 50 until the engine turns off and then the idle goes down with it until it's gone. There was a time when the stall happened that I received a message on the dash saying check alternator/battery, but I replaced the battery the day before and I know it can't be the alternator because the car just wouldn't start after. Also I can start the car and idle it in park without an problem, and have it sit in neutral as well without anything.

The funny part is that I can just turn the ignition off and turn it back on and the car starts up just fine. No problems for the next 20 meters and then the problem occurs again. I've noticed it does this mostly after a long drive, say 2-3 hours of driving with occasional stops. Recently however this has been happening just as I drive into town (15 mins).

I've had the car accidentally run out of fuel once before and it sort of feels like the same thing however I've never let it go past 1/4 fuel since then.

There are similar posts explaining the symptoms and various cures like Mass Air Flow Sensor, Idle Air Control/valve, fuel pressure regulator, and a crankshaft positioning sensor however I was told that the Idle Air control valve is working fine, and the CPS wouldn't work after it has failed. I'm not sure if the mass air flow sensor would be the problem since it feels more like the engine just isn't getting the fuel it needs but I may be wrong.

I did try to check the fuel pressure while it sat in park and idling and it seems like nothing was wrong until randomly I saw the pressure go from 50 to 30 in a matter of 6-8 seconds and the pressure shot back up to 50 again.. My mechanic said this is abnormal and should not happen in any case which is why I'm leaning towards a new Fuel Pressure Regulator.

I was hoping someone would have a solid idea of what may be the problem may be or give some insight. Is there a way to install a FPR without buying the whole fuel pump, regulator, and filter unit? (I'm almost positive it comes all in one bundle that won't disassemble)

I appreciate any help!

 

[DangTH]

Try unplug the wire at Mass air flow sensor.
This will bring your car into limp home mode. And see that...
if the car run better...your MAF is gone bad.
if the car run worse...your MAF is still good.

About fuel...you can ensure to flush out the air bubble which may left in the fuel circuit by go to the shop and make procedure like we bleed the brake fluid.

 

[Check Codes]

RP, please click user cp and edit details to add your vehicle and location to your profile, it's useful information when you're seeking help.

I would not recommend disconnecting the MAF at this stage of the game. That will set a code and the better course is to CHECK for codes as it is now. There could be several things causing/contributing to this issue and while the MAF is in the hunt, guessing (or unplugging things) could also mask the issue.

Disconnecting the MAF will set several ECU parameters to a default mode, so it's effectively bypassing lots of inputs. Thus, even if it runs better it might be one of the other sensors that it is bypassing that is the real issue.

So, check codes. Any OBD-II reader will work, if you're in the states Aamco shops will read them free and some auto parts stores will as well. Get the codes, then search here or post them.

Good luck.

 

[rp.merc.c240]

Thanks for the replies

I have checked the codes and nothing comes up unfortunately.

I have ordered parts to replace the fuel filter, turns out when I bought it a year and half ago it wasn't replaced yet, so god knows how long that's been sitting there untouched. I asked a couple mechanics and even one at mercedes and they said the MAF doesn't usually cause these specific symptoms and that it still could be the issue, that it sounded more like the fuel pressure regulator since it is apparently more common for that to go than the MAF. I ordered that as well for now, to my luck it comes as an entire unit ($500) including the fuel pump, regulator, and some other crap.

A little pricey but I figured I couldn't wait another day without a car to drive to work. I hope this fixes the problem, i'll post if it does.

But like I said, it's either of the two and I'm hoping I got the right part. I was also told that the MAF, if failed, it wouldn't fluctuate the fuel pressure drastically, that it would stay the same but lower psi, as in... My car's normal pressure is 50 psi and if it was failing or just screwing up here and there that it would most likely work at a lower psi constantly 30 or so.. I don't know if this information is correct but I mean who knows, I don't know much. I just know how to drive it.

 

[DangTH]

You know I been using alot MAF for my testing and found that bad MAF will cause the car run stranged eg. engine rev up and down unintention and also the fuel consumption is bad. The gear shift is rough.

After I change to the good MAF one, the car run normally again.

I suggest to unplug because you have not to pay anything and you can do it yourselve.

The code about MAF or related with engine can be erase simply by disconnect the battery negative terminal.

But you may need to calibrate ESP warning and windows syncronization. All can be done with out any tools you can find how to in this forum.

If you did not want to do these calibration or not disconnect the battery. Use car scanner is quite very convenient and more clear for what's going on with the car.

 

[rp.merc.c240]

So I replaced the filter which to no surprise was done, there was black fuel going out both ends. The pump and regulator also were replaced and so far I haven't had any problems I test drove it for 2 hours after installations and drove at least 2-3 hours a day since I got it back, added premium gas and injector cleaning fluid and it feels like the car is more willing to accelerate and respond than before.

I haven't had any issues as to decreased idle or any stalls yet. Once in a while I feel the gears change and it freaks me out because I keep looking for it to fail but apart from the paranoia I think this fixed the problem.

I'm going to cross my fingers that the next time I go for a long trip in this car that it would crap out on me again.

Thanks again for all the help, muchly appreciated

 

[DangTH]

Congratulation..! Sir.

 

[speedor7]

Same issue here

I have a c200k n having the same problem, runs fine except on idle it starts hunting, My tech says its the ECU, ny ideas on the sub.

 

[guitarzrule718]

I have a 2003 C240 sedan and I'm having the same problem.
However, my car does not completely stall. While stopped at a stop light, my car will start to sputter as if it's a bout to stall for a moment. Then, the car will rev up a bit and idle back up on its own. Also, after I stopped briefly to make a turn, when I pressed on the gas pedal it took about four seconds before the car would accelerate properly.

I spoke to the owner of my regular repair shop and he said it cold be a bad or failing crank sensor. I asked if we could be proactive and just replace it. He said, to be sure, unfortunately I'd have to wait until the car completely fails before they determine the problem specifically.

I scanned the forums and it appears it could be electrical, fuel filter and/or fuel pump, mass air flow sensor or crank sensor.

Is there any body else out there that's experienced the same problem? If so, what was the specific fix action?

Thanks in advance,
az

 

[rudeney]

Make sure the air cleaner housing (i.e. engine cover) is correctly installed tight against the opening of the MAF. That can cause "return to idle" issues.

 

[MYC320]

I'm having the exact same issues on my '02 C320...but mines are worse. I have to try like 3X's before I get the engine to start and when I do get it started I push the gas the car shakes and just dies on me. I got the main engine fuel pump and the fuel filter replaced in October of last year. I changed the Crankshaft Position Sensor, the Mass Air Flow and all 6 coil packs this month. The spark plugs got replaced back in October too because that's when I hit my 100K mark. I'm so frustrated...the only thing I can think that might be the problem is a vaccum leak somewhere, but I checked all the hoses...no cracks...so does anybody else have a clue of what else it might be?

 

[suvarb]

I have the same problem w 203 from 2002. It stalls on idle engine lamp comes on and when i restart the car a few times the light is reset. I have changed the hose below the airfilter but that did not help, i have had MB garage to do a diagnose, and they found nothing. I also have this absolute weird problem with windowasher fluid.... It only works below 2000 RPM ! Above that i can only get 4 squirts of fluid, then i have to restart the car again. And yes i know what you are thinking. The alternator regulator.... noops it gives 14.4-14.7 volt over the whole register , i thought that was the problem but no..... It drives me mad.

 

[MYC320]

I hate to be the bearer of bad news, but it's time to get rid of your C320. It's not worth the money nor time to invest in it anymore. Trade it in and get something else.

 

[DrKB]

Exact same problem

I have a 2003 C240 sedan and I'm having the same problem.
However, my car does not completely stall. While stopped at a stop light, my car will start to sputter as if it's a bout to stall for a moment. Then, the car will rev up a bit and idle back up on its own. Also, after I stopped briefly to make a turn, when I pressed on the gas pedal it took about four seconds before the car would accelerate properly.

I spoke to the owner of my regular repair shop and he said it cold be a bad or failing crank sensor. I asked if we could be proactive and just replace it. He said, to be sure, unfortunately I'd have to wait until the car completely fails before they determine the problem specifically.

I scanned the forums and it appears it could be electrical, fuel filter and/or fuel pump, mass air flow sensor or crank sensor.

Is there any body else out there that's experienced the same problem? If so, what was the specific fix action?

Thanks in advance,
az

Hey there, I know it has been a long time since you posted this. However, I am experiencing the exact same problem on my 03 C320. Two garages are failing at diagnosing the problem. Please tell me what did you find out at the end and what was the solution.

Thanks & Regards

 

[Iqra2707]

Mercedes ML 270 Engine problems

I have a Mercedes ML 270 with a diesel engine and I have had it serviced and they fit the oil filter, fuel filter and air filter in. This morning, my car wouldn't start the first time. After a few times of trying, it started. I had no problems up until the evening where my car randomly turned off and it took me 20-30 mins for it to start again. I just want to know why this problem has happened.

 

[rudeney]

Could be a bad CPS (Crankshaft Position Sensor).

 

[popond]

i am having the same problem on my merc c240 , 2002, 198k. oil filter changed, spark plugs, and crankshaft sensor. car runs fine at high speeds, at a stop downhill , low idle, will try to rev and go forward or have the 3-4 second delay when pushing the acceleration.
should i be looking into the MAF?, or maybe engine cover not seated well. i am afraid to take car now on long trips or around town because it may die on me at the wrong time, or like it happened yesterday in an intersection. after stop and start engine, everything works fine , like nothing is wrong.

 

[tjts1]

I'm running into a similar problem. 02 C320 152k miles. This morning with the engine cold when I accelerated it bogged down and lost power a couple of times. This afternoon it stalled when I tried to accelerate from a stop light. Restarted the engine and it drove fine. Going home accelerating up hill onto their freeway, no power. I had to floor it to make it up the hill. I checked both obd2 and MB specific codes on icarsoft and NO DTCs what so ever. I'm tempted to disconnect the MAF and take it for a drive since I'm out of ideas. I pulled the air box and I can't see any vacuum leak. I would appreciate any other ideas.

 

[Benzyle]

Check the ignition system,spark plugs,wires,coils.
Have you ever changed the fuel filter?
Check for dirty or clogged fuel injectors.
Check fuel pressure.

 

[tjts1]

Thank you. I don't think it's an ignition issues because there are no codes and no CEL. It's usually very eager to trigger the CEL when one of the 12 plug wires is loose. I think it might be a fuel filter or fuel pressure regulator issue (the FPR is built into the filter) because I have more fuel on the left side of the tank than the right.
https://i.imgur.com/W7Mke4s.jpg

An interesting read.
http://thefabricatorseries.com/build-blogs//c32-amg-w203-fuel-pump-issue

I'll swap in a new fuel filter this weekend and report back.