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99 Impreza OBS 2.2 PO304, Miss fire on #4 Cylinder


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The Daughters OBS was running a little rough off idle the last time she was down.  Now she has a miss fire on #4.  I did do Seafoam in the Intake and a Lucas Gas Treatment in the Tank the last time she was down.  Plugs have been changed to NGK copper core.  Going to have the #1 son swap the plug wires side to side and see if the fault follows.  

 

If an injector was leaking the plug would be fouled.  I have not seen the plugs, so hard to tell.

 

Valve Cover gaskets and the Spark plug tube seals were changed about a year ago. 

 

140+ K miles.

 

Other ideas?

 

Thanks, Larry

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I'm away from my garage, is the valve clearance set with the screw and jam nut on the 99 2.2.  

 

Thinking the valve may be slightly open.  I did clean the system with seafoam and lucas fuel system cleaner.  Could have cleaned the carbon off the valves?

 

Larry

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Coil was corroded on 2 of the 4 terminals.  Swapped the Coil and plug wires, new NGK copper core plugs and it's operating on all 4 cylinders again but still stumbles when you have 25-50% throttle in.  No codes but the plugs are very rich. 

 

Going to check the TPS, MAF, O2 and Knock sensor.

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Son had another coil from his buddy's car.  4 pin connector.  It started running on all 4 but then would not rev above 2500.  Very Strange.  I went up today, bolted on a use Subaru Coil I had, Problem Solved.  Lessons learned, Only use Subaru Coils and NGK or Subaru Plug wires.

 

Back on the road.  Thanks Larry

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