Volkswagen Repair: TDI BEETLE DOWN ON POWER, coolant temperature sensor, mass air flow sensor

Question
I JUST BOUGHT A 01 BEETLE,IT HAS 90,000 RUNS GREAT ITS JUST WEAK.I CAN HEAR THE TURBO ALITTLE,CAR SEEMS TO PULL BEST AT 1000 TO 2100.BUT AFTER THAT NOTHING.I TOOK INTAKE PIPE OFF FROM INTERCOOLER,THERE WAS ALITTLE SMOOT THERE AND A DROP OR TWO OF OIL ALSO.I'VE READ ALITTLE ABOUT INTAKE CLOGGING.IM PLANNING ON PULLING IT AND THE INTERCOOLER OUT TO CLEAN,BUT I JUST WANT TO RULE OUT ANY THING ELSE BEFORE I PULLER DOWN.I'VE TOLD MY WIFE THAT IT WILL RUN ALOT BETTER AS SOON AS I FIX IT.[I HOPE].AS A CRANE MECHANIC I JUST DONT LIKE WORKING ON MY OWN STUFF.I REALLY HOPEING FOR A BIG DIFFERENCE? ANY INFO WOULD BE GREAT . THANKS ,KEVIN

Answer
Hi Kevin;
The intake is probably clogged, and the mass air flow sensor is also, probably a contributor, as well as the engine coolant temperature sensor.  I would replace the MAF, and the ECT, and I would take off as much of the intake as you can get to, mostly the intake plenum at the back of the engine, yeah, the big aluminum piece, and take it to a machine shop to have it bead, or media blasted to get it clean inside, and then replace it all with new gaskets, seals, "O"rings...etc.  And I would expect that the difference in power will be about 60%...you are prbably losing about 60 horsepower...no joke.  Yeah, I'd say you should realize that great a return on your investment of time.  They hid a couple of fasteners at the back of the engine, and they are REAL NASTY to get to, but if you just take your time, and don't lose your cool, you'll get a great satisfaction from this repair.  Good luck, Kevin.  Hope this helps