Not your usual MAF problem

I need some help because I am the end of my troubleshooting abilities.

I recently purchased a 2012 Golf TDI w/ 6-speed. In 3rd gear when maintaining (not accelerating to) 30 mph (around 18000 rpm) the car begins to randomly vibrate as the engine rpm needle bounces around and it feels like the engine is sputtering a bit, causing more of a forward to back vibration. It'll happen in 4th too at the right rpm.

I thought I narrowed it down to the MAF sensor and here is what I've done so far:

- Disconnected MAF sensor plug.
>Everything smoothed out and problem went away.

-Removed MAF sensor to clean it, cleaned the connector contacts, and added some dielectric grease.
>Problem persisted

-Bought brand new OEM BOSCH MAF sensor and installed, reset ECU by disconnecting battery for a bit.
>Problem persisted

-Disconnected MAF sensor plug, again.
>Problem gone

and obviously when I plug it back in the problem comes back. Any ideas on what to do now?

Please help!!!

My only thought is to check the wiring.

My thought too so I gave the connector and the wires a look over and everything looks brand new, I suppose I could start piercing the insulated and check the connection between the pins and the wire but the wires go into the main Harnes after about 8 inches or so and I lose them

Update for anyone interested:

At the recommendation of a local VW tech, I dumped some fuel additive (diesel kleen) into the tank and proceeded to do an “Italian tun up” and drove the car like I stole it for a few days on the highway. Sure enough, the engine sputtering has stopped and everything seems to be fine!

My only thought is that the fuel system or injectors were fouled up some. By disconnecting the MAF sensor I enrichened the mixture which smoothed over the fuel delivery issues.

If the sputtering comes back I’ll let you guys know

VWGolfGuy said:

My only thought is that the fuel system or injectors were fouled up some. By disconnecting the MAF sensor I enrichened the mixture which smoothed over the fuel delivery issues.

Click to expand...

This makes total sense. Glad you've (hopefully) got it figured out!

The same problem is back and this after a 7 hour drive with Diesel Kleen at highway speed so now I’m stumped. Guess it’s just something I’m going to have to live with