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Old 08-29-2009, 04:27 PM   #1
holtian143
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Member#: 4014
Join Date: Feb 2001
Location: Ithaca, New York, USA
Default Misfire and Cat codes

Gentlemen,
I have stock 2000 Impreza RS 2.5, that runs like s**t. It's hard to start, taking about 4 seconds, normally when warm, usually not when the engine is cold.
The check engine light has been on for a few months, and I took it to AutoZone to have the codes read. All four cylinders are showing misfiring, and the "catalyst efficiency below threshold" code also came up. The code numbers were P0301, PO302, PO303, PO304 and PO420, I believe.
So, I changed the plugs today and put in the NGK plugs recommended in the Owner's Manual. The plugs I replaced were the same type, installed 11,000 miles ago. At that time I also had new ignition wires and coil installed.
This may be unrelated, but I also had a new exhaust system installed from the catalytic converter back about a month ago.
Possibly, I need a to catalytic converter. But, there may be something else going on.
I am at the point where I'm considering selling this baby. I just sold a Honda Civic VX today, and with 140,000 miles it still runs great. But I really would rather just be able to get the Subie running well again.
Any suggestions for the cause of the problems, or encouraging words, are appreciated.
Regards,
Randy Olson
Ithaca, NY
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Old 08-29-2009, 04:34 PM   #2
Charlie-III
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Join Date: Dec 2002
Chapter/Region: Tri-State
Location: 07456, North NJ
Vehicle:
1998 Legacy 2.5GT
Silver Sleeper Wagon

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What ignition wires were installed a while back?? If they were Bosch, that is your misfire issue. I stick to OEM wires.

How many miles on the car??
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Old 08-29-2009, 05:57 PM   #3
holtian143
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Location: Ithaca, New York, USA
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Charlie,
The car has 116,827 miles.
The ignition wires to the spark plugs are made by Autoparts International. They are red in color and say Silicone Mag Core on them. They were installed by a mechanic, and that company only sells wholesale (I googled them).
Hope this helps,
Randy
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Old 08-29-2009, 06:31 PM   #4
yarrgh
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Chapter/Region: RMIC
Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

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Is your front O2 sensor plugged in? Sadly enough, I'm not kidding. I made this mistake a couple of months ago and had semi-similar results. The car started fine when cold, but took 4-5 seconds longer to start when warm. Seemed to run fine too.

There are plenty of symptoms of a car running poorly. Give us more detail. How long have you had the car, when was the last time maintenance was performed, have you tried resetting the ECU? Do you have video/audio of it running?
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Old 08-29-2009, 07:06 PM   #5
holtian143
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Hey Yarrgh (is that your real name?),
Here are my comments IN CAPS (SORRY!):
Is your front O2 sensor plugged in? Sadly enough, I'm not kidding. IT WAS REPLACED BY A MECHANIC, AND I'M NOT SURE WHERE IT IS. CAN YOU TELL ME AND I'LL CHECK. I made this mistake a couple of months ago and had semi-similar results. The car started fine when cold, but took 4-5 seconds longer to start when warm. Seemed to run fine too. MINE RUNS FINE ON THE ROAD, TOO.

There are plenty of symptoms of a car running poorly. Give us more detail. How long have you had the car, I'VE OWNED IT FROM 2000 AND BOUGHT IT NEW. when was the last time maintenance was performed, THERE'S NEVER BEEN ANY REGULAR SHOP THAT HAS DONE MAINTENANCE ON IT. IT'S BEEN ME, OR AN OCCASIONAL MECHANIC FOR THE BIG ITEMS, LIKE THE HEAD GASKET. have you tried resetting the ECU? HELP ME OUT HERE. HOW CAN I RESET IT? Do you have video/audio of it running? NO, THERE'S NO AFTERMARKET A/V EQUIPMENT.
Randy
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Old 08-29-2009, 10:25 PM   #6
Charlie-III
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1998 Legacy 2.5GT
Silver Sleeper Wagon

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Front O2 sensor, is in the exhaust right in front of the front CAT (in the header).

ECU reset, disconnect the battery and let the car sit an hour or so.
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Old 08-30-2009, 09:44 AM   #7
holtian143
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Location: Ithaca, New York, USA
Default

I checked the O2 sensor and it looks like it's connected right in front of the catalytic converter, with the wiring and connector intact all the way into the wiring bundle where it disappears. So, it's fine.
The "check engine light" is now off, after disconnecting the battery for an hour. That's a pleasant, although probably temporary, relief.
Does anyone have an opinion on the ignition wiring from Autoparts International?
Lastly, I reread one posters comments about uploading a audio visual clip of the car while it was running. I can probably do that. Do I use the "insert link" icon at the top of this page? Or, do I use the "insert image" icon?
Randy
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Old 08-30-2009, 11:32 AM   #8
holtian143
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Join Date: Feb 2001
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Default Video

Here's a link to the video of the car while running:

Hope this works; this is the first time I've posted anything on YouTube.
Randy
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Old 08-30-2009, 11:34 AM   #9
yarrgh
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Join Date: Jan 2005
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Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

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Inserting a link should be fine. Have you tried cleaning up the grounds in the engine bay? do a search for "big 3" or "grounding mod" in the electrical section, that may help your car run a little smoother.

that's good that you've owned it this long, since you know the history of the car. When did it start running poorly? Was there a significant change right before? I can only assume that it was the recent plug wire/coil pack change that led to this.

Try to re-seat the plug wires both on the coil pack and the plugs themselves to see if that has any effect.
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Old 08-30-2009, 11:38 AM   #10
holtian143
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Location: Ithaca, New York, USA
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Let's try linking the video again; the first time didn't work.



If that link didn't work, you can just go to YouTube and search for this video:


I think this should work.

Randy
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Old 08-30-2009, 12:18 PM   #11
yarrgh
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Join Date: Jan 2005
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Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

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when's the last time your valve lash was adjusted?
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Old 08-30-2009, 01:03 PM   #12
Back Road Runner
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Silver

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Does the car run fine cold?

Does the car run fine under heavy throttle?
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Old 08-30-2009, 01:43 PM   #13
holtian143
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Join Date: Feb 2001
Location: Ithaca, New York, USA
Default

Yes, the car runs fine when cold or warm. It also accelerates well, running fine under full throttle. It just is a little slow starting compared to all my other cars (three Honda Civics, a '69 Jag, and '77 MGB).
And, the check engine light seems to keep coming back, although it's off for the moment after disconnecting the battery for an hour.
Valve lash? I don't think the valves have ever been adjusted if that's what you mean. Did they sound loud in the video?
I haven't checked all the ground connections, but can look around later.
The car also seems to smoke a little more than it should when I start it up in the morning. White smoke. Smells oily. Could be from the plugs not igniting all the full and clogging up the catalytic converter (just one theory).
Thanks for all the help so far.
Randy
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Old 02-15-2010, 09:06 PM   #14
skifree09
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I'm having similar problems. So far replaced coil, wires, plugs, O2 sensors, cat converter... not sure what the ultimate cause is at the moment. Fun times.
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Old 02-15-2010, 09:10 PM   #15
dohtohrhi
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Location: Simi Valley
Vehicle:
2000 2.5rs
silver

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compression test/front o2 sensor...
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