Volvo Owners Club Forum - View Single Post - T5 only 0.3 bar boost and poor throttle response

Welton · Jan 28th, 2019, 08:23

My lovely T5 has suddenly become lazy and I can't figure out why.

In July 2017 I changed the Turbo Control Valve (TCV) just for maintenance sake and replaced it for an OE Pierburg unit so that should be ok, the Vacuum lines all 'look' ok no real signs of chafing/splits. I've changed the little 'one way' breather valve on the turbo a few months ago. I've changed the Fuel Pressure Sensor couple of years ago. Air filter is good, loads of oil changes with top-spec stuff.

Throttle is kind of 'dead' and the car even sounds a bit quiet, no check engine light and only achieving 0.3 bar on my Torque Pro app.

One definite change is that I used to be able to hear the Compressor Bypass Valve (l think this is Volvo's equivalent of a Dump Valve?) sort of 'chatter' when maneuvering at low speeds and a 'whishhhh' sound between fast gear changes, this sound has gone so I'm wondering if the Turbo is not generating full boost because the bypass/wastegate is partially open.

Any suggestions please I'm sort of stumped and I hate the car feeling like this, I'm almost praying for the engine light to come on to give some clues.

Jan 28th, 2019, 08:23	#1
Welton Premier Member Last Online: Sep 14th, 2021 17:03 Join Date: Feb 2009 Location: Market Harborough	T5 only 0.3 bar boost and poor throttle response My lovely T5 has suddenly become lazy and I can't figure out why. In July 2017 I changed the Turbo Control Valve (TCV) just for maintenance sake and replaced it for an OE Pierburg unit so that should be ok, the Vacuum lines all 'look' ok no real signs of chafing/splits. I've changed the little 'one way' breather valve on the turbo a few months ago. I've changed the Fuel Pressure Sensor couple of years ago. Air filter is good, loads of oil changes with top-spec stuff. Throttle is kind of 'dead' and the car even sounds a bit quiet, no check engine light and only achieving 0.3 bar on my Torque Pro app. One definite change is that I used to be able to hear the Compressor Bypass Valve (l think this is Volvo's equivalent of a Dump Valve?) sort of 'chatter' when maneuvering at low speeds and a 'whishhhh' sound between fast gear changes, this sound has gone so I'm wondering if the Turbo is not generating full boost because the bypass/wastegate is partially open. Any suggestions please I'm sort of stumped and I hate the car feeling like this, I'm almost praying for the engine light to come on to give some clues. __________________ 2005 S40 T5 SE - Manual. Bilstein B4's. (For Sale) 2010 Citroen C4 1.6 HDi (bizarre Gearbox model). 2010 Renault Twingo (refreshingly simple) 2018 Infiniti Q30 1.6T Business Executive (what's this button do?)