Want to be able to fix my #1 cylinder that is miss-firing. My OBD reader is giving code P0301.

Tiny
IMPALA PAIN
  • MEMBER
  • 2004 CHEVROLET IMPALA
  • 75,000 MILES
A year ago I changed my upper and lower intake/head gaskets on my car(thank god for Haynes). In the last 6 months I changed my belt, the water pump, and the breaks. When I changed my breaks a code for Cylinder 1 started popping up and now stays on all the time P0301. The spark plug is clean but missing the spark piece(appears broken) I have put a new spark plug in but the same code popped up. I took the oil cap off to check the vacuum and idle dropped and went rough when I did that. Not sure where to check Vacuum on Intake though. There does not appear to be any anti-freeze leaking which there was lots of right before I initially replaced the Head Gaskets, thermostat etc. I have read that it could be a fuel injector causing the misfire on the specific cylinder or worse. Any hints or ways to rule things out? The head gasket replacement was the first car repair I have ever done since than I have done everything on it and only in the last month has there been a problem but no fluids or loss of coolant. Just the engine symbol and the code. Help me please.

signed,
frustrated Chevy Impala owner
Monday, December 5th, 2011 AT 12:51 AM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Before you do any work, check the compression in the #1 cylinder. Something broke the plug and may have caused damage to the cylinder causing it to miss.
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Monday, December 5th, 2011 AT 1:13 AM
Tiny
IMPALA PAIN
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What is the best way to do that?
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Monday, December 5th, 2011 AT 1:22 AM
Tiny
RASMATAZ
  • MECHANIC
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Use a compression gauge to determine the ctaul compression of no.1 cylinder-should be 10% tolerance from the other cylinders-Are the plugs OEM parts-maybe too long of reach-worn plug
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Monday, December 5th, 2011 AT 1:27 AM
Tiny
IMPALA PAIN
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  • 5 POSTS
When I changed the head gaskets I changed all the plugs and it was a champion I have now put Bosch in. The original plugs were acdelco. I have noticed that certain parts have to be acdelco ie:thermostat, serpentine belt tensioner all have to be acdelco. U think I should put acdelco plugs in? Would it make a difference in plugs?
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Monday, December 5th, 2011 AT 1:37 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Have you checked compression?
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Monday, December 5th, 2011 AT 2:20 AM
Tiny
IMPALA PAIN
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No I will check compression next
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Monday, December 5th, 2011 AT 2:36 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Let me know what you find.
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Monday, December 5th, 2011 AT 2:59 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
CONCERN HERE IS THE BROKEN PLUG

SEVERAL THINGS COULD CAUSE IT, HERE'S JUST A FEW

1) BROKEN DURING CARELESS INSTALLATION

2) WRONG PLUG (INCORRECT APPLICATION), TOO LONG, MECHANICALLY DAMAGED BY ENGINE

3) BURNED OFF, COMBUSTION ISSUES

4) MECHANICAL PROBLEM W/ ENGINE BROKE IT

MANY PLACES (SHOPS) HAVE CAMERAS THEY CAN PUT IN THE PLUG HOLE AND LOOK FOR DAMAGE

SOUNDS LIKE YOU LIKE "DIY"----ME TOO!

THE COMPRESSION TEST MAY TELL SOMETHING TOO

THE MEDIC
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Monday, December 5th, 2011 AT 5:22 AM
Tiny
IMPALA PAIN
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  • 5 POSTS
First off let me address the sparkplug issue
-im an idiot that just threw it in my tool box and than all my tools on top after I first pulled it. ( Thanks to my wife for pointing that out. So I have access to the Compression Test kit but a mechanic down the street told me to change the coil and wire and see if that fixes the code. I took the plug into a mechanic and he said it was to clean to suggest any damage done by the motor.

I am going to do the Comp. Test though just to make sure.
No harm no foul.

Happy to report that I change the coil, the wire, the just replaced spark-plug (no damage) am the code has been cleared and has3 not returned after a week of driving which should be more than enough time to reset the cylinder misfire code if it was not fixed
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Tuesday, December 13th, 2011 AT 2:27 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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That is good news. I'm glad you got it fixed.
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Tuesday, December 13th, 2011 AT 4:36 AM

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