QuestionI have a 02 TDI with 200,000klm on it. Recently it started losing power and is getting worse. I have had it to two dealers and they can't figure it out. There is no Check Eng light on or no codes being registered. The dealer says the turbo is fine and they have changed a few sensors but I think they are throwing parts hoping to solve the problem. I have changed fuel filters with no difference. I am at wits end. I have read intakes will clog up, could this be the problem? How difficult is that to tear apart?
AnswerHi Chris;
Yes the intakes will clog with a build up of carbon deposits, and there will be no codes. However, this is a time consuming, difficult, and expensive repair that requires sublet labor to a machine shop to remove all of the deposits in side the intake, and turbo because they are on there like concrete. The first thing to look at is whether it could be a MAF(mass air flow sensor). It is far less expensive, far less time consuming, happens as often, or more than the carbon deposit problem, and it too will throw no code. Finally, and this one is more in the believe it or not category, the "ECT" engine coolant temperature sensor could also be telling the engine computer that the temperature outside is 100 degree Fahrenheit, when it is actually 60 degrees, and that will reduce the fuel that the injectors are allowed to put into the cylinders, and that will reduce power..a lot! With a diesel there is only one way to increase power...given the same air flow....and that is with fuel. The ECT is the cheapest of the 3. The turbo cleaning, and intake manifold, and throttle body "de-coking" can be $2000.00, yep that's right 2 grand. I'd eliminate the other causes first, because the ECT is only about $65.00 installed, plus tax. The MAF is probably $220.00 done. So, you could have both of the cheapest ones done for under $300.00, and if you still have the same problem, you will know for sure it is the throttle, turbo, intake combination that need to be cleaned. They are just such a darned problem to get on, and off. There are hidden fasteners on the back of the cylinder head, that require an inspection mirror just see, let alone remove. Low quality, inexpensive diesel fuel is the primary reason for this condition, along with extended intervals between oil changes. I know they require synthetic oil, but with the extreme levels of heat generated by the turbo, synthetic oils breakdown too. I hope this is informative, if not too helpful Chris, I'm sorry to hear about the problem you are having. Shop around, but take the car to someone who knows Volkswagens, not just the cheapest place, or you will be disappointed with the repair. Good luck.
