Using a 2.0L MAF in a TDI
In the TDICLUB discussion forum an extensive discussion is going on (May 2002) about using the 2.0L MAF (06A 906 461A) with a TDI engine. The 2.0L MAF is interesting as it goes for something like $50 (In the US, not in Europe!) in stead of the usual $250! A TDI usually has a 06A 906 461 MAF. (so without the 'A' extension) Also Pierburg MAFs can be found in TDIs (074 906 461), but on this page only the Bosch MAF is discussed. If you have a Pierburg MAF and want to use a Bosch 2.0L MAF, contact me. It can be done.
Some people claim to have excellent results with the 2.0L MAF, but others experience excessive smoke. The smoke is probably caused by a higher output voltage of the 2.0L MAF. The ECU 'thinks' that more air is going into the engine and allows more fuel to be injected. This will result in smoke (and maybe extra power) To compensate for this larger signal, a really simple circuit can be placed between the MAF and the ECU (engine control unit). The circuit is a simple attenuator made by only two resistors. The output wire of the MAF is cut and the circuit is placed between the MAF and the ECU.