I installed 2 magnets in my fuel line as fuel saver. During the 1st 150 km my fuel consumption dropped down from 5.4 l/100 km to 4.1 l/100 km; then the computer wake up and started to throw more fuel in the system resulting in increase of consumption. After some googling I found out that I had to fool the computer by usen a MAF enhancer (for diesel). However when driving with my caravan fuel consumption dropped down from 11.5 l/100 km to 8 l/100 km. Now having a very rich mixture the computer accepted this and did not interfere. I installed the enhancer and found that tuning by hand is tricky because the computer gives a message when turning the knob to far, and returns into an emergency procedure sothat I have to reset the ECM. But I have 10% less fuel used. So I will install an electronic device to do the job.
What gains may I expect when adding a HHO unit to the system? Has anyone experience with this combination? I drive a Volvo S80 2002 diesel 2.5l automatic.