Update -
tl;dr Had to prime the fuel pump and lines manually (ie couldnt prime by opening/closing drivers door or cycling to ON position) but the fuel pressure is steady if nothing else. Seems MAF could be bad, wiring or unit. Looks extremely clean upon visual inspection. Codes come up with cyl 3 misfire and MAF and Intake Air Temp Sensor (which is new, but related to unplugging the MAF?)
Battery - steady 12.66v resting; steady ~13.65v at initial idle; ~14.05v to 14.20v when misfire and rough idle begins
Fuel pressure -
55psi after priming and drops slightly to steady ~50psi resting and primed; steady 60psi when idling, even with rough idle and misfire. What is spec?
after priming fuel pump with a spare 12v and a jumper wire because the fuel pump wouldnt prime when cycling the key to the ON position. I double checked the fuel pump relay and fuse and they both check out. I also checked jumping car battery positive to the right side of the fuel pump fuse and checked voltage at fuel pump electrical connector and it is reading just about the battery voltage so the wiring appears to be good. However when I test the voltage at same connector when cycling the key to the ON position I get a reading of 0.10v which drops to 0.06v
MAF -
Unplugged after the misfire and rough idle began. No change in behavior, RPM or anything so this indicates I guess bad MAF. I will look into cleaning and further diagnosis when I get back to AllData at the local library. Visually it looks great though the wire loom protection has worn through leaving still-in-perfect-shape wires ’somewhat’ exposed. Anyone know the textbook diagnosis of MAF for this engine?
Codes -
P0300 - 001 - Random/Multiple Misfire Detected
P0303 - 001 - Cylinder 3 - Misfire Detected (counts seemed better but screwed up the logging)
P0102 - 002 - Mass Air Flow Sensor (G70) - Signal too Low - Intermittent
P0113 - 002 - Intake Air Temp. Sensor (G42) - Signal too High - Intermittent
Next steps?