My 2017 Toyota Highlander Limited (3.6L engine) has started to "whistle" when running. When removing the new fuel cap I put on 8 months to a year ago theres a vacuum inside the PCV valve was replaced the same time as the fuel cap. I've pulled it off and cleaned ti but it seems to be in good working order. But the engine stumbles before shutting off like an old diesel truck. I'm thinking evap system but not sure where to go or if I have to wait until it trips a code.
A diagnostic scan for codes and live data would be a good start.
@chucktobias
I wish I could give codes but my scan tool does not give any other than a drivers side airbag sensor error not even an engine light.
There can be pending codes that have not triggered the check engine light, but most scan tools should be able to check for those. Likewise most scan tools these days, even the cheap ones, can display live data so it would be a good idea to look for clues there.
When removing the new fuel cap I put on 8 months to a year ago theres a vacuum inside
You're sure it's vacuum and not positive pressure?
Either the computer was in the middle of performing a purge or a leak test, or you have a blocked EVAP system. Blow out the lines.
PCV valves aren't expensive so if you're not sure it's working right just replace it.I've pulled it off and cleaned ti but it seems to be in good working order.
All kinds of things that can cause this so start by examining the fuel trims. They might point to a problem area. (specifically, check the live data)the engine stumbles before shutting off
As mentioned above you need to do more analysis. A code isn't tripped until it meets a certain level which is determined by the manufacturer. No code does not mean you don't have a problemI have to wait until it trips a code
