This is a different expert.
The 172 code means lean mixture on bank 1. I'm a little surprised you don't also have a 136 for bank 2.
These engines are notorious for the large vacuum connectors sucking a hole right through them that only opens up when the engine is running. Many times they are hidden under or behind the plenum where they can't be seen.
The easiest way to find this stuff is using a smoke machine pumping smoke into a vacuum line and looking for the leak,
Don't rule out that the 0/2 sensor may just be reading wrong also. You can monitor the 0/2 voltage while artificially enriching it to see if the sensor responds when it sees the rich m ixture.
Saturday, October 31st, 2015 AT 4:54 AM