A few weeks ago, my check engine lite came on. Had a P0171 code which is the left bank lean. When I ran the codes, we went into PID commands and all HEGOS were functioning fine. Upstreams switching fast and normal. Cleared the code and now 2 weeks later, it's back. I've read on ther threads about a vaccum leak under the manifold? My truck hasn't been idling very well lately, so I'm wondering if this is a known issue. I have 86K on my 2004 5.4L. THe mechanic that viped my truck said that this type of code takes alot of trouble shooting so I'm trying not to go to the dealer. (especially when they told me I needed all new ball joints and they are fine)! Thanks for any ideas and help..

 

hey guy there is a vacuum line that goes in the intake manifold down low check it first drivers side low comes off the brk booster line ..... hard to see and hard to get to