New? Start here. There are 600 Volvo forum users online now. See the forum's active topics. Say hi contact Matthew.
MVS-Amazon link helps MVS!

Blow off valves on a 1998 V70R?

Let’s about Blow off valves

How Blow Off Valves Work

The blow off valve is opened on lifted throttle as the flow under pressure in intake system through intercooler and hoses is abruptly stopped and the pressure wave will effectively bounce off throtle and go backwards through turbo. This causes stress on turbo and can go backwards through MAF sensor. MAF registers the flow either direction so the ECM could get a signal and meter additional fuel and create a momentary over-rich condition if throttle is not completely closed (completely closed cuts off injectors on closed throttle, no fuel delivered, not rich). The BOV lets air get dumped to inlet side of turbo and the turbo pulls that in again and it effectively creates a temporary recirculation to stop the backflow. This also allows turbo to keep its speed up so a re-application of throttle results in faster boost build again.

Blow off valve on a 1998 V70R?

Welcome to Matthews Volvo Site! Your one stop shop for all Volvo news, help and DIY fixes. We feature the Volvo Repair Database, the best Volvo Forum, and an awesome monthly Volvo newsletter. Joining is always free!

Subscribe to the MVS Newsletter

The MVS Volvo Newsletter is a once-a-month email delivered to your email. It’s simple to unsubscribe at any time if you change your mind.

Visit The Official Volvo Cars Website

Leave a Reply