Hi guys,
Did an OBD 2 scan of my 97 Ford Explorer v8 5.0L. It came back with
the following codes.
PO304 ---------cylinder 4 misfire
PO153 ----------O2 circuit slow response bank 2 sensor 1
PO133 ---------- O2 circuit slow response bank 1 sensor 1
PO171 ----------System to lean

I am looking for a couple of pieces of information that maybe
different people may have experience with.


1. Do all these put together indicate one problem or multiple
problems
that need to be addressed


2.The O2 sensor has not been replaced since I have owned the truck in
2000 so I imagine that outside the misfire on cylinder 4 these are
overdue for replacement.


A) Are the O2 sensors the same in all locations or are
they different types, (i.e. can I order 2 of the same or are their
differences between the O2 sensors located in different locations of
the truck.


B) Anyone knows a website with pictures of the locations
of these sensors, or can describe these locations.


Any advice or how to's is greatly appreciated.

dsd91 wrote:
Generally speaking, address the first code that comes up first; solving
the first will often clear (some of) the others.

dsd91 wrote:
This looks like 2 separate issues:
-#4 cylinder misfire
-Vacuum leak
It is possible that the system is leaning out the mixture to compensate for the dead
cylinder, but I believe the lean code would only be for the affected cylinder bank.
Your Explorer will have 4 Oxygen Sensors. One in front of each catalytic converter
and one after each converter. The downstream sensors are Catalyst Efficiency monitors
and do not have anything to do with the Air-Fuel mixture. The chance of both upstream
O2 sensors failing is pretty slim, they just don't fail as often as many folks believe
unless they are contaminated for some reason.
I would suggest that you address the misfire, clear the codes and drive the vehicle.
If the lean codes return start looking for a vacuum leak. (Of course, keep a lookout
for obvious leaks while fixing the misfire).

On May 21, 10:51 am, Tom Adkins <nos... (AT) centurytel (DOT) net> wrote:
Is there a a very obvious place to start looking for vacum leaks? I
remember I did have that problem a year ago and a machanic fixed it.
Are most of these vacum hoses on top under the hood or underneth the
engine from below.

dsd91 wrote:
had a vacuum line under the upper plenum that was prone to leaking. This was on older
5.0L engines, so I'm not sure about your Explorer. If you look at the emissions
sticker, I believe it should have a vacuum diagram showing the relative location of
components.