[jammy_c]

Hey guys,

So here’s the deal;

My GT TDI 130 has a severe lack of boost, you can hear the turbo spooling up, but accelleration is very poor. No signs of black smoke, engine runs really smoothly and does high 50’s MPG.

A friend of mine has VAGcom, which was plugged in and brought up the code “Mass Air Flow sensor open circuit/short to groundâ€￾. Assuming this was the problem, the component was replaced with a brand new one, and this has not fixed the fault, it keeps reproducing the same fault code. 
If I unplug the MAF sensor it doesn’t make any difference to the engine running.

The MAP sensor seems to give sensible readouts via VAGcom.
The VNT Actuator movement seems free.

Any idea what else it could be? If it’s a vacuum leak, would it still cause an error code? Would I still get no boost?


Thanks in advance guys!

 

[jammy_c]

Thanks! I'll check the wiring and vacuum hoses as my first port of call. I have been planning on checking the continuity between the MAF, N75 and EGR plugs back to the ECU anyway, but keep relying on the aweful british weather, which keeps letting me down

 

[jammy_c]

yeah, it transpired that there was a break in the wiring inside the plug boot that plugs into the MAF. i soldered it back to the pin and instantly regained boost. i think the open circuit caused the ECU to go into limp mode.

 

[jammy_c]

Very true, it took a long time searching and checking things.
The fault code (using VAGCOM) was “MAF sensor open circuitâ€￾, so I replaced that first of all. that made no difference, so I got a pin-out of the ECU and checked continuity from the ECU back to the pins in the MAF plug. One of them had no continuity, so I traced the wire, no breaks or snagging, so I opened the plastic boot on the back of the plug to find the wire had come away from the pin.
:nana2: