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1997 Subaru Legacy Cylinder

Tiny
KECLARKE
  • MEMBER
  • 1997 SUBARU LEGACY
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 211,000 MILES
I did a diganosis test and I get a P0304 code. My cylinder 4 misfire detected. How can I fix this problem. I'm a certified Michanic of 15 yrs, but I've not done this work in a few yrs. Please help me fix my problem. Kristine
Friday, September 10th, 2010 AT 2:39 PM

7 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Hi keclarke, Welcome to 2carpros and TY for the donation

P0304 Start by checking no.4 sparkplug, compression and injector
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Friday, September 10th, 2010 AT 4:19 PM
Tiny
KECLARKE
  • MEMBER
  • 4 POSTS
I did check all those things and I still get the same diognostic code. Lastnight, my check engine light came on and I did the diognostic test and it said p0304 again. What else could it be that is causing the misfire?
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Saturday, September 11th, 2010 AT 6:17 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
What's the compression reading on no.4 If all of these components tested good-possibly a wiring problem or the computer itself-Did you check the plug wire and coil resistance for this cylinder
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Saturday, September 11th, 2010 AT 8:00 AM
Tiny
KECLARKE
  • MEMBER
  • 4 POSTS
The compression of the no. 4 is about 90 psi. That should be enought to fire. I also checked to wiring and seem to have spark. I'll check to coil resistance of the cylinder. If all that pans out, could it be a possible lifter problem? Thanks.
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Saturday, September 11th, 2010 AT 10:23 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
With that mileage -Hard to say on the lifter also try checking the no.4 injector resistances. Did you replace all the plugs
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Saturday, September 11th, 2010 AT 10:28 AM
Tiny
KECLARKE
  • MEMBER
  • 4 POSTS
I replaced the no. 4 injector and no. 4 plug. I'll have to look at the coil resistance.
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Saturday, September 11th, 2010 AT 10:39 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Compression pressure service limit is 128 psi. At 90 psi the compression pressure is too low and can result in misfiring.

Check the valve clearance. If it is too tight, it can result in pressure loss.
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Sunday, September 19th, 2010 AT 1:30 PM

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