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Okay, over the last 20,000 miles (currently 131k) I have had an ongoing issue with surging / rough idle, etc. The codes, when it finally appears when the car becomes undrivable, has been low maf output.
So each time I replace the MAF, the car works great for a few thousand miles and then the signs start to slowly return.
I am now on MAF #2 and its starting to return again. Now, I can believe that the reman bosch mafs (only thing you can get) are garbage, but this is ridiculous. I have also replaced the throttle pedal at one point and it made no difference.
So what else is there? Is this a unique issue? are there other areas I should check?
Other culprits are plug wires PCV pipes and a coked up throttle body.
If the MAF keeps checking double check the connections on the PCV pipe on the side of the housing. Over oiled KnN filters will disturb the MAF as well.
Got the same issue with an '05 clk55 as well. Mine has 115k miles. Looks like you're my twin. First time around it was the gasket underneath the maf censor that holds the air seal. I replaced that, might of been two. Not sure what it is this time.
I had/have the exact same issues with my '05 clk55. I've had vacuum pipes replaced and a gasket can't remember which one off the top of my head. MAF and secondary air pump. Fixed the car for a few months and it's started coming back. The new faults are "mass or volume air flow circuit A intermittent" and "intake air temperature sensor 1 circuit". My mechanic has assured me it's something very minor and it doesn't affect the car once I get passed the low revs. Hope this helps but just my experiences. I'll post again once I get these things sorted. Good luck.
I had/have the exact same issues with my '05 clk55. I've had vacuum pipes replaced and a gasket can't remember which one off the top of my head. MAF and secondary air pump. Fixed the car for a few months and it's started coming back. The new faults are "mass or volume air flow circuit A intermittent" and "intake air temperature sensor 1 circuit". My mechanic has assured me it's something very minor and it doesn't affect the car once I get passed the low revs. Hope this helps but just my experiences. I'll post again once I get these things sorted. Good luck.
vacuum pipes as in the intake hoses that connect to the grill? I replaced mine too, ran my hand underneath and both hoses had a huge hole in them from dry rot over the years. That was another issue 20k miles ago that solved the maf at one time too
The 2nd MAF i put it i replaced the lower seal. That worked for a time, but now i've been seeing it again. The check engine light has not yet turned on though. It did have an episode a few months ago, before changed the transmission fluid, then it went away. But now its starting to come back.
I see no obvious signs of vacuum leaks, but i will make another round on it. The air filter housing is firmly seated.
any chance that you are using K&N filters with oil...the oil has been known to kill MAFs...also, when you are finishing, be sure to properly seat the rear of the air filter onto the MAF housing and then gently lower the front down onto the clips...if you don't have that good seal, the engine will have same issues that you describe (even with a good MAF)
I’ve got a very similar issue with my car. 2003 CLK55 with 125k miles.
I replaced the MAF and the car ran perfectly for a few hundred miles but now back to shaky idle and feeling sluggish / like it is going to stall under breaking.
Codes before the MAF were P2017 and P2086. I checked recently and had the same codes, in addition to P2016 and P2085.
I am wondering whether these cars use a default map (maybe fuelling based on engine speed) for a period when a MAF is replaced. We all think the issue is solved until the car starts using the MAF values. That would make sense if there were
an intake leak after the MAF.
My codes are showing fuel trims on both banks, so it really has to be something between the MAF and the point where air splits across the banks. Or a bad MAF.
Not a 55 but I’ve had the surging issue for a couple of years now but only from morning cold starts. Always goes away once the engine gets warmed. Tried everything already mentioned and no ones been able to figure it out including my independent mech and the dealer.
Not a 55 but I’ve had the surging issue for a couple of years now but only from morning cold starts. Always goes away once the engine gets warmed. Tried everything already mentioned and no ones been able to figure it out including my independent mech and the dealer.
Sorry, I probably wasn’t as clear as I should have been. It persists when the engine is warm, but is worse when cold.
Looking at the attached, I replaced all of the breather hoses apart from 176. Wondering if that is an issue. A very similar part on the M113K of the E55 appears to cause similar issues.
My gut feeling is that something very similar has happened on my CLK55. My purge valve is also quite noisy, and I am wondering whether that could be linked.
CLK purge setup below.
A generic post from the web: If the canister purge valve fails and sticks open, it will create a vacuum leak that can affect the engine idle speed and quality. A vacuum leak can also be created if the purge solenoid, or any of the hoses that may be attached to it break or become damaged.
Other culprits are plug wires PCV pipes and a coked up throttle body.
If the MAF keeps checking double check the connections on the PCV pipe on the side of the housing. Over oiled KnN filters will disturb the MAF as well.
Cheers, Gator
I just took a look under the bonnet and pulled the MAF. Breathers and purge hoses all seemed good. I’m not 100% on whether the rubber seal for the MAF was seated properly (it has dimples that I may have missed the first time) but it is definitely seated properly now.
I am leaning towards it being the throttle body.
There is a great post on Benzworld that looks like it covers it here.
I’m not sure whether it would qualify as a vacuum leak, since air going into the engine would be via the MAF, but if the valve is not closing properly it might throw an issue with fuel adaptations.
Have ordered TB cleaner and will attack it over the next week or so.
EDIT: This has now been solved. I had not fitted the rubber boot below the MAF properly and it was letting in unmetered air. Reseated and all is well. With two Liqui Moly fuel cleaner bottles run through two tanks and with the new MAF it is running sweeter than ever.
07-05-2017, 12:02 AM
