I have owned from new a 2002 9-5 3.0 TiD which has now done 67000 miles. This is a low mileage with the lowest rate of increase most recently as the car is mostly used locally with little chance for high speed.
Every now and again the car starts to get lumpy (and who can blame it) so, after warming the oil, it gets a clearout with some full throttle in third uphill. It’s no good doing this on the level as it doesn’t last long enough. Normally the view out of the rear window is obscured but the pipes are cleared and it can pass the MOT smoke test without having to go through all five max r.p.m. tests.
When I last did this it started to accelerate as normal but above 2000rpm lost enthusiasm. Eased off accelerator and service normal until full throttle resumed.
Took car to local Saab specialist who hooked up Tech2 after a test drive which confirmed boost being reduced over 2000 rpm as if it was overboosting, which it wasn't.
Tech2 showed no codes.
Other tests showed that EGR valve was working as expected and that wastegate operated freely.
Turbo was also shown to be free.
As the visit was at short notice, that was as far as it got but with no ideas as to what it might be.
Since the visit, I have tried it with a bottle of Forte Diesel Treatment, more in hope than expectation, as a couple of years ago there was a fuel related roughness which cleared.
Before I take the car back to the Saab specialist, does any one have any suggestions?
