OBDII codes:
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:
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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.
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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.
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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?
PO171and PO174, System Too Lean (Bank 1 and 2)
PO301, Cylinder 1 Misfire Detected
____________________________________________________________________________________________________
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.
____________________________________________________________________________________________________
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?
Mar 17, 2015 at 1:25 PM
