PO171and PO174, System Too Lean (Bank 1 and 2)
PO301, Cylinder 1 Misfire Detected
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Parts Replaced:
Spark plugs and plug leads (Coil Pack tested and passed), PCV Hose Assembly (Gromit was torn). Erased codes with scanner.
Result: Misfire temporarily eased and then returned to it's audible state after about 30 miles, and codes returned.
Parts Replaced:
Upper and lower intake manifold gaskets, and header gaskets. *Also, replaced coolant and ATF.
Result: Codes went away voluntarily, and misfire seemed to disappear for about 60 miles, then returned to it's previous state. Code PO304 returned.
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The diagnoses continues:
Vacuum gauge test:
Passed; reads consistently at 20, and when rev'd, drops quickly to 0, jumps quickly to 25, and settles quickly back to 20.
Mechanical causes of misfire thus not pursued.
Inline sparkplug tester used to check cylinder one spark plug lead; passed.
Fuel injector harness leads tested with multimeter; all 6 read a steady 11.8v.
Fuel injectors tested with multimeter; all read consistent 11.5 ohms; meter set at 200.
Running out of ideas, I replaced the cylinder 1 injector.
Still, misfire is audible. Still PO301 code on scanner.
Things I have not done:
-a noid light test on injector harness leads.
-a fuel pressure test.
-a compression test
-a leak down test
What could be causing this misfire? Where should I go from here?
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Tuesday, March 17th, 2015 AT 1:25 PM
