1987 9000T auto in New Zealand.
Problem. The turbo gauge does not show any vacuum at idle and on the
overrun. The boost side is ok, it goes nicely up to the yellow/red
area. The only problem I have found is that the vacuum advance on the
distributor is broken, but would this leak be enough to cause the
above?
We tried swopping the dump valve for a known good one but this had no
effect.
Any ideas please?