I have a "beige" (metallic gold, but it says beige on the rego sticker) 2008 GV with the f9q diesel that has suddenly developed a problem.
We went on a ~700km journey with 5 adults and luggage and averaged ~10km/L (according to the dash), we then did a quick ~200km journey with just 2 people and got ~15 km/L, then returned home with another ~700km and ~10km/L. Since then it has stayed around the 10 - 11 km/L mark.
We had it serviced after we got back (75000km logbook), and the mechanic said they didn't change the timing belt because they couldn't source one, and it was ~$300 when they could, and it didn't make a difference to fuel usage and drivability.
When driving, the car is very low on power for up to a second, before coming on boost strongly and suddenly, and goes like a cut snake up top (with ~20PSI, not surprising!) I bought a scan gauge and hooked it up and I am getting 15PSI driving normally and nearly 22PSI if I need to accelerate hard or hold speed up a hill on the highway. There are no ECU codes reported. I have tried disconnecting the battery overnight and there is no change.
Before this, we would get ~14km/L in town and 14.7 - 15 km/L on the open road, and boost would build slowly in a surge, not suddenly in a rush.
After a bit of reading, the VW pumpe duce 1.9 diesel is very sensitive to timing changes and has the same symptoms (Browser Warning
), but the f9q is common rail. I am taking it to a diesel guru on Monday, but talking to him he didn't have any ideas what it could be, I did discuss timing and he will check that, but does anyone have any ideas about what else could be causing it?