1996 850 non-turbo | P0455 vacuum leak

[jdw]

I'm trying to resolve a vacuum leak on my 96 850 non-turbo manual for an upcoming CA smog check. Check engine light with code P0455 started appearing after a PCV job.

I've read posts like viewtopic.php?f=1&t=54546 on the typical leak areas but haven't found the weak spot.

- Hoses to the charcoal canister seem ok. Both hoses seem to hold pressure.
- Hoses near the tank including roll-over valve seem in-tact.
- EVAP purge valve holds vacuum (one way not energized, other way energized).
- Small hoses connect to vacuum T all hold vacuum except for the line to the airbox. Is it ok for the vacuum line to the airbox to hold no vacuum? Should the connection to the airbox (see arrow) have a check valve?
- A home made smoke tester mounted with a rubber glove over the intake is not indicating any leaks

Thanks in advance.

[RickHaleParker]

Did you check the gas cap seal for leaks?

Possible source

• Leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP canister shut-off valve or lines between these components.
  
  Blocked canister purge (CP) valve, EVAP canister, fuel tank pressure sensor or pipes between these components
  Sticking canister purge (CP) valve
  Defective fuel tank pressure sensor.

P0455 = EFI-611.

[jdw]

Thanks for the reply Rick. The seal in the filler cap is dry but not cracked. I might just get a new one as it never has been replaced.

A lot of failure points identified by EFI-611 are near the tank. Maybe I should do some more smoke testing in that area.

The following components were not ready when the CEL came on: Catalyst, EVAP system, Oxygen Sensor.

Anyone know if the white tube going into airbox should hold vacuum? Thanks.

[abscate]

Yes it does. It drives the air box motor to regulate the air box temperature, so it doesn’t hold vacuum it’s letting in unmetered air into the throttle body