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Misfire Problem

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The valves look like they are in good shape along with the guides....i have enough fuel, timing is on, i have spark (new plugs and wires and coil pack).....any help here would be great.....

We really need more detials here and some clairity.

 

why were the heads off, if they werent how did you determine the guides are good (not they have anything to do with anything).

 

The engine is in one peice?

 

The engine won't start?

 

nipper

  • Author

my fault.......the engine is a 2.2 Liter in a 1996 Legacy I found out the valves were good with a vacuum test, compression test, and i removed the downpipes and looked up into the heads.....i figured if the guides werent good than you wouldnt get a proper seal in the combustion chamber.....The engine is in one piece i just want to figure out what else i can check until i started digging into the internals. The car starts and runs great....the only time that i get the "MIL" is when im at idle also that is the only time that the misfire is heard . ( i hooked up my scan tool to it and every time i have cleared the code i look at the freeze frame data it always occurs around 500-1000 RPM)

Have you done the basics?

 

new OE wired and plugs?

 

nipper

  • Author

yeah i have changed out the plugs a few times because i have heard that subarus are very "touchy" when it comes to ignition componants..... same with the wires.

the big fat aluminum resistor on the firewall? check that as i have seen that misfire on a 91 legacy and still after an engine swap. changing the resistor fixed it

  • Author

are you talking about the igniter?

I would check it over well for a vacum leak. With the engine running at idle spray around the intake and hoses with some carb cleaner and see if the idle changes. If that's good try moving the injector on the cylinder that missfires to another cylinder and see if the miss follows the injector.

Lets try basics. With the engine running, remove one spark plug at a time. Does the miss go away?

 

this will tell us if its a single cylinder issue or a floating issue.

 

 

nipper

  • Author

I will give that a try tomarrow....that sounds like a smart idea.....Every time i plug the scanner in though it comes up with the same code P0302 which is cylinder #2.

I will give that a try tomarrow....that sounds like a smart idea.....Every time i plug the scanner in though it comes up with the same code P0302 which is cylinder #2.

 

 

Would be interesting to see what happens to #4

 

Could be as simple as a cracked coil tower.

 

nipper

  • Author
Would be interesting to see what happens to #4

 

Could be as simple as a cracked coil tower.

 

nipper

 

 

well i tested the coil pack and the resistances were correct.... primary and secondary. someone told me that the IAC could cause something like this it it is like clogged or dirty.....they said it would like shut off a cylinder to maintain proper idle....have you ever heard of anything like that?

well i tested the coil pack and the resistances were correct.... primary and secondary. someone told me that the IAC could cause something like this it it is like clogged or dirty.....they said it would like shut off a cylinder to maintain proper idle....have you ever heard of anything like that?

 

It shuts off #1 cylinder.

 

 

Your over thinking what im saying.

 

Its a physical hairline crack in the coil tower.

 

Another test. With the engine running, wet the coil, wires, with a mist of water. This is best done in the evening. Look for blue sparks.

 

nipper

  • Author

that is also a good idea..... i will give it a shot.....assuming i see blue sparks i should replace the coil pack?

IF you have OE wires, yes you should look at that possability.

 

Something else to try, swap wires from 2-4 to 1-3 and see if the miss moves

  • Author

will do.....in all luck it will be something inexpensive......thanks for the info

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