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01 Fozzy check engine flashing


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Hey gang!  Long time.  I did some searching and didn't find what I was looking for, so...

My 2001 Forester (I got it with 153k, it has 178k now) started with some flashing CEL and rough running ("the muffler was banging"), causing the mrs to smartly circle back to the compound and park it.

I've done some digging on the Google and it looks like this is likely tied to a misfire of some kind. I replaced plugs and wires with new NGKs (along with new valve cover gaskets and a new fill tube o-ring as there was a decent amount of oil buildup on that side of the engine).  Took it for a test drive and all seemed fine- no flashing CEL, ran like normal.

A few days later, I fired it up to take it for another spin around the neighborhood and the CEL was flashing right away and exhaust smells rich.

What should be my plan for trying to chase down the misfire?  Check ignition coil pack next?  What about after that?

 

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You don’t need a reader to find the codes. There are two black connectors above the driver’s feet. Connect these, turn the ignition ON and watch the check engine light - long flash = ten, short flash = one. 

So if you had two long, three short, two long, four short, two long, three short, two long four short - you’ve got two codes - 23 and 24. Look those up and you’ll have your offending sensors. 

Sounds like an O2 sensor I reckon. 

Cheers 

Bennie

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Yeah, I have an OBD reader.  No codes to start.

I tried starting it a bit ago and it was turning over, but wouldn't catch.  I tried a few times and got it go after giving it some gas, but it was tough.

Checked codes tonight and got P0301, P0340, and P0302.

Very strange, as it had no trouble turning over last night and did not run rough.  Definitely shook more tonight, which makes sense if I'm getting a misfire on cyliners 1 and 2.  I have no idea why the camshaft position sensor would now be kicking a code.

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I did have the cam position sensor unbuckled when I was replacing the fill tube o-ring and valve cover gaskets, so I popped it off again and cleaned a bit of residue from the connections and reconnected to make sure it was solid.  That seemed to solve the P0340.

I followed the FSM info on checking the resistance of the primary and secondary connections on the ignition coil.  The secondary (across 1 & 2 contacts and 3 & 4 contacts) checked out within the range in the FSM, but I was unable to get any resistance readings through the primary pins combos (1 & 2 and 2 & 4).  I went to a salvage yard today and checked a couple of coil packs there, there were two that mimicked the same behavior (secondary resistance within range, unable to get any resistance readings across primary pin combos). 

I bought one of the coil packs and fired up the Foz a couple of hours ago and no codes are coming up and the engine runs smooth, so there do not seem to be any misfires.   One test drive was without trouble.  I'm going to take it on a few more spins around the 'hood and make sure it does not pop codes again. 

Interesting problem with an interesting assortment of suggestions.  Thanks to all for the input.

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5 hours ago, upnorthguy said:

I was unable to get any resistance readings through the primary pins combos (1 & 2 and 2 & 4).

I'm not sure what year they started putting the Ignitor inside the Coil pack, but I think it is on yours. Our 95 and 97 have the Ignitor mounted on the center of the firewall.

You have to set your ohm meter to the Diode setting and it will only read in one direction. Reversing the probes it will read open. The Ignitor has high current transistors in it that fire the coil so the ECU doesn't have to handle the load of the coil or the feedback pulse. When you are checking the input of the coil you are checking the Base (input) of the transistors and bias resistors, NOT the primary winding of the coil like on the old ones. With a little ingenuity they can be tested, but that doesn't mean it will work properly on the engine.

You did the best thing by replacing it.

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