ghiaguy

I was having issues with the car shuddering at idle for a while now. It finally got bad enough that I looked for a solution. My motor/trans mounts are done and the throttle body inlet has been cleaned recently.

I looked into MAFs expecting them to be expensive, but found units from reputable sellers on Ebay for around $30. Shipped fast and securely with caps on both ends; I was delighted with how far my money went. The install was a breeze and before I knew it I was back on the road. Or so I thought...

First drive had the car surge aggressively at every stop, then act as though it hit a fuel cut if I gave it more than 1/3 throttle! The damn thing even stalled on me once!
I chalked it up to the car having to learn the MAF since when drove it again and it was perfectly fine...

This morning it acted like hell again, another surge and stall and I finally nursed it to the parking garage. I will swap in the original MAF, but wtf?!? I don't understand why it would work so erratically. Its easy to say that the ebay part is bad (and it may be) but these sensors are simple/easy to produce and really shouldn't be the $$$ that MBZ charges...

Any thoughts?!? I have a hellacious work day ahead of me, but can't get the damn car out of my mind. Thanks guys

cm60k

Any diagnose or codes before replaced MAF..?,

most of ebay MAF's are remanufactured or chinese wholesalers copies, they put original Bosch photo for deceiving purpose..

ZAYED,,

ghiaguy

No CEL at all- will codes be present even if there hasn't been a CEL? Do I just need to use an OBD II reader to find codes?
Thanks

cm60k

Sure, you can use any good OBDII reader, or preferably STAR/SDS...

ZAYED,,

ghiaguy

Cool - I have one, but haven't had to use it on the C55 yet. I guess that's where I should start...
Thank you!!

alboogiee

I was in the same boat about a year ago after I bought a Bosch MAF off eBay for cheap when my OEM one started showing symptoms. The eBay MAF did the exact same thing you're describing so I took it to my indy shop and paid for another Bosch MAF at close to retail and problem solved. I was told that eBay and Amazon MAFs are bought in bulk and often are ones that may not be up to par for our application even though same PN. Not saying you need to pay full price or give the dealer your business but a more reputable seller with a better inventory of MAFs may yield better results.

Regarding the OBDII reader, mine would only pick up codes when the car would throw a CEL. This only happened when the fuel was cut and/or stalled.

ghiaguy

Yeah, it seems like a quality unit but it certainly made the car worse. I hope I can go back to the original MAF and the car will forgive me until I snag a proper Bosch unit...

I will try my OBDII reader, it has worked on my Dad's 2003 E39, but wouldn't work on my gf's 2009 MKV Jetta. Thought that was strange...

Thanks for the replies!!

cm60k

Any time..,

If you don't get any thing from that reader at this time,

try to unplug the first "2" O2 sensors, and remove the airbox for a short ride, and see what's the differ...

ZAYED,,

Saaboteur

I go with what alboogiee said. I had a similar experience on my C43 (which, if memory serves, uses the same p/n MAF as the C55). El cheapo MAF would give the same surging or "engine or trans is about to break" feeling. But the proper Bosch unit back in and ran perfectly again.

Heh...MAFs are like shoes - buy cheap and you'll end up replacing them sooner rather than later. Better to just spend more up front and get a quality item. AutohausAZ seems to have good MAF pricing.

ghiaguy

Yeah, I think I'm going to go that route. The original MAF still worked (way better than the new one) so I'll reinstall it while waiting for the new Bosch unit.
I have CRC MAF cleaner spray- should I use it to clean up the original? If so, how liberally should I apply it? It feels strange spraying a liquid on a sensitive electrical sensor!

Tump43

Yes, clean your MAF with CRC. Follow the directions on the can. But a couple of good sprays and letting the MAF dry completely before reinstalling should do it. I always clean my MAF before concluding I have to replace it. Cleaning should be done once or twice a year anyway, depending on conditions.

ghiaguy

I wanted to pop in with an update:
I thoroughly cleaned and re-installed the original Bosch MAF after work yesterday and the car is back to driveable! The slight tremors I experienced on occasion are still there, but that is likely due to something else. I hope that surging and violent power cuts didn't cause any damage... Truth be told, I will not be ordering MAFs off eBay anymore as the unit was clearly defective.
I didn't end up pulling the trigger on the MAF at AutohausAZ since I wanted to see how a thorough cleaning would work out, but they seem to be the way to go if I need one in the future.

Thank you all for your assistance!! Enjoy the rest of your week