Throwing codes

[SpiderKenneth]

Hey all, I'm a bit new here, have had my explorer about 4 months

Bought It for 400 with a bad transmission, now I got the transmission rebuilt(still having issues )

Anyway, I'm getting a code for bank 1 sensor 1 detecting lean; a buddy of mine pulled the codes and when he did, didn't tell me what the code was, just told me to buy a new O2 sensor, I got the motorcraft one and installed, still throwing same code. This thing is gutless as hell, as well, I'm not sure if they all are.


Anyway, any ideas of what can do this?


It's a 1996 4.0 OHV

 

[koda2000]

O2 sensors don't normally throw lean codes. You probably have a P0171 code (lean on passenger side/bank 1).

Possibilities include:
Vacuum leak on intake manifold
Clogged fuel filter or weak fuel pump (although will usually effect banks 1 & 2)

 

[SpiderKenneth]

I was thinking a vacuum leak..

How normal is the intake gaskets to leak on these? I took ether to all the vacuum lines and around the intake and I couldn't get the idle to change

 

[manimal]

The OHV is known to develop vacuum leaks at the upper intake gasket (really O-rings) and fuel rail gasket - the fuel rail sits between the upper and lower intake.

The upper intake O-ring type gaskets are easy to replace and most with higher miles seem to need it done.