Low MPG

Hi and thanks for using 2CarPros.

A computer is an electronic device and like anything else, they can fail. If you think the computer may be wrong, do this.

Fill the fuel tank. Write down the mileage on the vehicle at that time. Drive the vehicle until you use at least half of the fuel. Refill the tank and note how many gallons were needed to refill the tank.

Next, look at the present mileage and subtract the miles that were on it the first time you filled the tank. That will give you the miles driven since the first fill up.

Take the miles driven and divide it by the number of gallons needed to refill the tank. That will tell you your average MPG.

Once you do that, determine if you are averaging what the computer is telling you. It should be close.

Try that. Sorry for the math lesson, but I did not know how else to explain it. LOL

I hope this is helpful. Let me know if you have other questions.

Take care,
Joe

Interesting. The smoke was most likely the result of too much fuel. Has the smoke stopped?

If you adjusted the camshaft drive belt you also altered the engine timing. That is not something you should do as that alone will cause excessive fuel use. Blue smoke is usually due to bad valve stem seals or on the VW's a bad PCV valve system or bad turbocharger seals that let oil into the system. I would start by setting the timing back to original. Then remove the turbo and look for signs of oil use. To test the PCV system is easy. With the engine running remove the oil filler cap. If the system is working it should come off with a very slight hiss from a vacuum. If however you can remove it and oil mist and vapor comes out, and if you set the cap in the hole it tries to lift at all the PCV system is faulty.

The altered timing has lowered the intake vacuum enough that it is not drawing oil past the seals.