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

2004 CHEVROLET IMPALA

75,000 MILES

IMPALA PAIN

MEMBER
5 POSTS
FOLLOW

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

Dec 5, 2011 at 12:51 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 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.

Dec 5, 2011 at 1:13 AM

IMPALA PAIN

MEMBER
5 POSTS

what is the best way to do that?

Dec 5, 2011 at 1:22 AM

RASMATAZ

CERTIFIED EXPERT
75,992 POSTS

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

Dec 5, 2011 at 1:27 AM

IMPALA PAIN

MEMBER
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?

Dec 5, 2011 at 1:37 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Have you checked compression?

Dec 5, 2011 at 2:20 AM

IMPALA PAIN

MEMBER
5 POSTS

no i will check compression next

Dec 5, 2011 at 2:36 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Let me know what you find.

Dec 5, 2011 at 2:59 AM

CJ MEDEVAC

CERTIFIED EXPERT
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

Dec 5, 2011 at 5:22 AM

IMPALA PAIN

MEMBER
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

Dec 13, 2011 at 2:27 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

That is good news. I'm glad you got it fixed.

Dec 13, 2011 at 4:36 AM