Blow-off valves, an after-market option for vehicles, are an important part of any turbo engine system. They relieve the flow of compressed air caused by the closing of the throttle. These valves help the vehicle's engine perform better and increase the life of your vehicle's system. However, blow-off valves also have several cons that affect your vehicle's performance.
Some types of blow-off valves cause a drop in the overall performance of the vehicle's engine. Unfortunately for fans of the blow-off valve's noise, it is usually the noisier types of blow-off valves that are likely to adversely affect a vehicle's performance.
Blow-off valves can cause your car to stall momentarily when you let your foot off the gas. This is due to a problem with the blow-off valve's tension. You can fix this problem by tightening the tension on the blow-off valve so it closes faster. You may have to adjust this several times, while test driving the car in between tries. Improper installation can also adversely affect the lag time during which the car changes gears.
Sometimes, the air that moves between the blow-off valve and the compressor will become hot, and this can damage your engine.
If you are driving a car in which the blow-off valve is mounted after the mass airflow sensor, you may have problems with your engine control unit, or ECU. The venting of the blow-off valve causes the ECU to think it has a different level of air in the intake system than what is actually there, causing it to inject the wrong amount of fuel into the engine system.
