September 19, 2011 Products

Tech Tip: BOV Troubleshooting

If you have installed a vent-to-atmosphere BOV and your engine has started to dip below normal idle and stalling, follow these steps:

BOV Troubleshooting Steps

  1. Firstly, check that the BOV is closed at idle. If the BOV is not closed at idle. Theres a good chance that the spring tension may need to be increased or the BOV might need a heavy-duty spring.
  2. Next, check the vacuum hose for splits, cracks, loose connection, kinking or any obstruction. It is important that you replace old or fatigued hose's. It also important to know these hoses may collapse under vacuum causing an obstruction.
  3. Lastly, with the engine running remove the vacuum/pressure hose from the nipple in the cap of the BOV. You should hear a loud hissing sound. The engine should idle poorly. Double-check by covering the end of the hose with your finger. If this does not occur, the hose could be blocked or crimped. Thoroughly check the hose and replace it if necessary.

If the stalling dipping idle is still occurring follow these steps:

BOV Troubleshooting Steps

  1. First, ensure that the vacuum/pressure source is not shared and that the vacuum source is directly from the inlet manifold.
  2. Next, check the seal between the adapter and the BOV – ensure that there is no gap between the BOV base and the weld flange.
  3. Lastly, check the join between the adapter and the intercooler pipe for leaking.

Note: It is important to know that some cars with sensitive Air-Flow Meters will not respond well to atmospheric Blow-Off Valve. Turbosmart recommends fitting a bypass-type BOV like the Plumb Back. Consider fitting a bypass-type BOV as it will eliminate the stalling problem.

BOV Troubleshooting Diagram  

Further Reading

The question, 'Can a BOV damage your engine?' Has been solved. If you want further reading check out the following related articles: