850 T5 boost problem

When the weather gets cold (below +7 C = +45 F), my T5´s turbo starts to
give too much boost. Only a very, very minor push to the gas pedal is needed
to get the car run like hell. If I push the pedal to the end, the ECU starts
to cut fuel. When weather gets warmer, the problem disappears.

The engine temperature does not effect at all, it´s the same if the engine
is cold or warm.

Help!????

 

Your car has electronic control of the wastegate. Check the hose from
the wastegate actuator to a valve mounted up near the air filter box.
This hose clips into a small strap on the back of the engine. From that
valve, follow the other 2 hoses, one to the turbo, one to the air intake
hose. Make sure all 3 hoses are in good shape and clear inside. This
is a lot easier said than done.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

I suggest just replacing the hoses, they're just normal vacuum line aren't
they?

 

This is a similar problem to the T5 not boosting at all, and not
unusual.

For some strange reason, the boost pressure sensor is mounted several
feet away from the turbo, at the end of a very long and thin hose (it
routes near the radiator and the air filter, but you'll have to find
it by tracing it from the manifold - there are any number of thin
black hoses under there).

If this hose falls off, you lose boost. If it blocks (usually owing
to water inside it freezing), then you get over-boost. Try blowing
through it (ideally with some dry air) and checking the connections.

 

The only problem with that is if there was nothing wrong with the hoses
in the first place, then you won't have fixed your problem. I think
they're just normal vacuum hoses, you just have to make sure you get the
right size.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)