GMC Repair: Engine misfire, mass air sensor, mass air flow sensor


Question
Hi, I have a 1996 4.3L GMC Jimmy.  The engine has been missing from time to time for the last month.  I replaced: plugs, wires, cap, rotor, PCV val, fuel and air filter to no avail. The engine light just came on the other day and it gave a diognostic reading of Camshaft position sensor and mass air sensor (PO306) which my manual list as a cyl #6 misfire.  My question is where to go from here?  Thanks for the help.  -Ryan

Answer
Hi Ryan. let's take this one step at a time. First, you tell me you have a cam sensor, mass air flow sensor and a misfire in #6 cyl code and that your check engine light came on, so let's work on that first. You need to write down all the codes and then clear all codes. When your engine light comes on again, check and see which code is making it come on as soon as possible, there will probably be only one code stored. Have you checked for vacuum leaks in the #6 intake runner or any other vacuum sources? There is also the posibillity of a dirty fuel injector. Another area to check is the ignition coil and wire, pay very very close attention to these for they are problem sources. Do you have access to a diagnostic scanner so you can read all the sensor inputs and outputs? Get back to me and let me know about these questions and i will of further help to you. MANFRED