I have an 04 Vectra dti auto, now with 127 000 miles on the clock and until recently it's been a very good car (ok changed one front shock link and the rear roll bar rubbers and the usual brake pads etc).
However not long back it would start, run badly for a couple of seconds, then cut out. It was recovered to (non main dealer) garage who did readout and diagnosed boost pressure sensor. Changed. Car worked. Seemed to be a result.
Then started getting the spanner warning light. It would go away for only a couple of miles after switch off/on & seemed to be actuated by accceleration. A long night journey to Scotland in limp home was therefore a bit of a nightmare.
I went to a VX main dealer who read out P0234 and P0638 fault codes and said the fault was a sticking throttle control solenoid. No spare stocked so they freed it off & the car was OK for a couple more weeks. They advised a "new solenoid valve" if the problem recurred. Apparently they were referring to "induction manifold upper" part 24459897 about £230!
Then about 10 days back, return to square 1, the car would start, run badly for 2 -3 secs & then die. I discovered that removing (and plugging) the little vacuum tube from the top vacuum powered actuator on the inlet manifold immediately cured the starting problem & the car seems to be running fine!
In the Haynes manual there's no mention of this actuator and in the photos it's not even fitted!
So questions - a) Presumably the actuator on the inlet manifold works a throttle butterfly inside. What's it for and does it matter if it's disconnected?
b) There's a second vacuum powered actuator down the side of the inlet manifold. What does that do?