C5 2.0 Hdi - No Power until 3500-4000rpm then whoosh....

wheeler · Post by **wheeler** » 04 Nov 2009, 12:59

I would agree that it is still the ECU controlls boost pressure.

Giving the turbo a direct vaccum (ie joining the two pipes at the turbo electrovalve) will give you constant full boost on a 110bhp 2.0 HDi, just pulling the pipe off will result in no boost at all.
The 2.2 HDi works the opposite way, if you disconnect the vac pipe from the turbo it rests at full boost.

The turbo electrovalves are quite common failures, The boost pressure sensors are not that common to give any trouble unless the little plastic pipe has been broken on it when the air filter has been changed, this is very easy to break if you are not very careful.

HDI · Post by **HDI** » 04 Nov 2009, 13:15

So the wastegate is held shut by vacuum instead of the actuator spring pressure ??!!

wheeler · Post by **wheeler** » 05 Nov 2009, 02:57

HDI · Post by **HDI** » 05 Nov 2009, 10:53

Very strange !

Old-Guy · Post by **Old-Guy** » 05 Nov 2009, 18:05

Oh, I'm so glad I deliberately bought one of the last entirely mechanical 1.9XUTDs!

Electronic controls and automotive-quality electrical components - anything to save a penny (or centime) - are a recipe for problems in the long term.

cachaciero · Post by **cachaciero** » 09 Nov 2009, 23:43

Based upon my experiences with the 2.2 which runs on electronics and vacuum I would strongly recommend that if you have a problem with anything that has vacuum control first make sure that the actual vacuum is what you would expect i.e that there are no leaks as certainly on the 2.2 the flexible pipe joiners harden and crack causing variable vacuum losses.

cachaciero