sick Snowball

Nigel Prodrive

Nigel Prodrive

Dirt surfer
poor Mr Snowball is very unhappy. bucking/chugging on accel @ low revs, then smoother but with a lil s-st-sttutter as revs rise. runs ok on light throttle. intermittent PO540 code, cat below efficiency bank 1, code has been present ever since Borla headers went on. chugging is getting gradually worse to point where sometimes it sounds like there is backfire in intake.

no misfire codes, no sparkage around coil pak. no vac leaks that I can find. plugs and wires are recent. no oil leaks around cam covers, plug boots are clean. no sign of HG probs except oil leak under pass side head.

have my own theories, what does the assembled wisdom of MS remote diagnostics crew think?

 
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Unplug the sensor and see what happens. A plugged cat makes a very distinctive sound. You could try and remove and o2 sensor before the cat and see if it revs normally.

 
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It did something like that when I first got it. I replaced the front o2 sensor, and it went away. I don't think I had it scanned for a code at the time.

 
tanks guys, apparently applying $71.99 at the neighborhood AutoZone will make all my problems go bye bye (well at least some of em anyway)

a bit o googling turned up a great home remedy 02 sensor test that involves voltmeter, vise and a propane torch....can't wait to burn the bejeezus out of that lil sucka whether it passes or fails!

will report full results here (or you may read about results in log of Camden fire dept)
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Post up that test, please. (maybe Mods could make it a "sticky".....) I'll bet we all could use that eventually.

 
Interested in results. I've got similar, though probably not as bad, symptoms and also have oil in one side of the heads (forget what leaked, but I remember hearing its hard to fix on a phase 2 and not really necessary).

edit: valve cover gasket

 
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Stein said:
Interested in results. I've got similar, though probably not as bad, symptoms and also have oil in one side of the heads (forget what leaked, but I remember hearing its hard to fix on a phase 2 and not really necessary).

edit: valve cover gasket
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it's necessary to fix if the oil leak is making one or more of the plugs or plug booties go bad and cause a misfire, BTDT

 
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My 97 OBS did that when the MAF was bad. Inski brought over his car and we tried his and it ran like a champ. I'd check that MAF.

 
Our RS was running and accelerating like crap for a bit a couple years ago. After normal testing and tune up replaced front O2 and could feel the difference the first time I let the clutch out. I hope that's your case, I have heard of other sensors going bad, but O2 is the best place to start.

 
<OT>

So I hadn't put it all together until just now. You bought this RS from 4WRXter right? If I follow my members right this is your car from a STM group drive back in 06 that I led...

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</ot>

Hope its running better soon.

 
FYI for all you 00-02 peeps.

The front O2 sensor that has a cam lock type connector have been very problematic over the years and Subaru has a reflash to go with the new O2 sensor.

While watching the AF#1 correction percentages on the Subaru monitor you could see +/- 25% which is maxed out for what the computer can adjust to. A good o2 will show +/-5%-10%. The reflash seems to make the O2s last longer but I have no idea whether or not theres an actual parameter change going on during the reflash. Every car in this era I've come across with similar symptoms as you're describing has needed this reflash and o2 sensor.

P0540 code does not exist for your car.

P0420 is Cat efficiency below threshold.<---I don't think this has anything to do with your lack of performance

A problem O2 wont necessarily set a code. that's why we look for the AF correction percentages.

Nigel, which code do you have?

 
inski said:
FYI for all you 00-02 peeps.

The front O2 sensor that has a cam lock type connector have been very problematic over the years and Subaru has a reflash to go with the new O2 sensor.

While watching the AF#1 correction percentages on the Subaru monitor you could see +/- 25% which is maxed out for what the computer can adjust to. A good o2 will show +/-5%-10%. The reflash seems to make the O2s last longer but I have no idea whether or not theres an actual parameter change going on during the reflash. Every car in this era I've come across with similar symptoms as you're describing has needed this reflash and o2 sensor.

P0540 code does not exist for your car.

P0420 is Cat efficiency below threshold.<---I don't think this has anything to do with your lack of performance

A problem O2 wont necessarily set a code. that's why we look for the AF correction percentages.

Nigel, which code do you have?
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PO420, it has been lit more or less continuously since I got the car. strange thing is, it's gone out my itself a few times. if cleared with my reader, it almost always comes back on after a couple starting/cooldown cycles.

so is the reflash a dealer thing? Snowball tends to skeer dealer service writers and techs, they don' like how much he has been modded.

and yes, Snowball is 4WRXters old ride. He reports having similar prob with the car a couple years ago, tossed in a new sensor and fixed issue immediately. new sensor din't last long, guess it's time for a new 02 sensor and ECU lobotomy.

 
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