The Cast: 99 Outback Wagon, 169,000 miles:slobber: (I know, it's a lot), 2.5L DOHC, standard trans.

 

The Plot:

My CEL came on with a P0303 (misfire in Cylinder 3). So I replaced the plugs and wires. Still getting the P0303. Checked the resistance on the ingition coils last night and was a little perplexed. According to the Tech bulleton I was referencing for the resistance test http://endwrench.com/images/pdfs/DirectIgnition.pdf

the primary resistance should be .70 ohms +- 0.3 ohms and the secondary should be 21 KOhms +- 3 kOhms.

 

My primary resistance was 1 ohm for both terminals, within spec but barely. My secondary resistance was 13.9 Kohms, out of spec but both coils were exactly the same.

Since the tech bulleton doesn't specify a model year I was wondering if there is a different spec for 99 2.5L DOHC. It seems unlikely that both coils would deteriorate simultaneously at the same rate and cause the exact same out of spec reading. Especially since the misfire is always reported in Cylinder 3 (8 consecutive PO303 codes). The coils have never been replaced. Do they eventually just go bad?

 

Weird, still, is that the car seems to be running just fine other than a sporadically rough idle and sometimes a knocking noise when it idles. At speed, the car runs perfectly.

 

Any input would be greatly appreciated.

 

Thanks

Possibly blown headgasket your about due for one, check exhaust color and smell (don't breath for to long:confused: ) color will be continuously white, depending on how bad it is, and will smell sweet. Also check oil dip stick, you will see a "milky" appearance to the oil.....but I'm just a backyard hack mechanic maybe others will ideas.

 

check for lose connection on sparkplug wire.

Already had the head gaskets replaced at 113,000. Havn't noticed any white smoke from the exhaust so I'm hoping the head gaskets aren't the problem. Ive had the sparkplug wires on and off a couple times now so I think I can rule that out also. But thanks for the ideas.

 

RMB

 

Possibly blown headgasket your about due for one, check exhaust color and smell (don't breath for to long:confused: ) color will be continuously white, depending on how bad it is, and will smell sweet. Also check oil dip stick, you will see a "milky" appearance to the oil.....but I'm just a backyard hack mechanic maybe others will ideas.

 

check for lose connection on sparkplug wire.