sick Snowball

Still, its a pretty sweet looking little car. Looks like my buddie's fiancee's old car we called zippy. It was auto, but it was a real screamin deamon. I dunno what if anything had ever been done to it, but I have not driven an automatic before or since that put the hammer down like that thing could.
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it IS a pretty sweet little car, had a blast driving to work on April Fool's Day Blizzard morning....days like this are what the RS was built to do! It's color is called Alpine White, so it's a borned snow-mobile.

looked at 5 RSes while shopping this time round, bought the best of the bunch. time to attack the dang rust bubbles tho!

 
I've never done just the o2 without the reflash. I suppose there have been plenty of o2 changes without the reflash, I just don't know about them.

 
so...old sensor flunked the bench torch test. OK, cool.

ordered up fresh Bosch A/F sensor...quick install super easy to reach, BUT car still stumbles/farts/coughs at low revs

gaaargh now what??!!
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swappin out coil pak on lunch break today, we'll see

I really hate the "throwing parts at it" way of solving probs.

 
coil pak switch, no difference.

double-triple checked vac lines, seem ok

what's next. throttle position sensor? unhooked it, car ran worse. hooked back up, still chuggin

my book is the Haynes manual up to 98, not much help troubleshooting an 00!

main symptom is chugging/hesitation under accel from low revs. at higher revs or light load, runs fine.

W T F ??!!

 
Can't your car be hooked up to a diag tool at the dealer that can identify which sensor is malfunctioning? It was my understanding something like this was done on our RS back when it was running bad. Or they just got lucky replacing O2...

 
Iboc_C64 said:
Maybe your CAT is actually clogged and its not a faulty sensor.
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Maybe this is true... or is damaged from ongoing issues with running. Mine died on my car, so maybe I fixed it with a hammer... funny how mine opened up after that. Also hows your fuel filter, HAS CAR SAT LONG? If it has E10 fuel and sat longer than 2 months on one tank with no stabilizer than possible that water separating out of your fuel (killed my dads snow sled (until flush tank) 2 years running). take line off your filter if suspect true, see how much fuel comes out when crank (fill a clear dry soda bottle, use little hose from fuel outlet of filter), hold bottle up to light if cloudy it is no good, if let sit long cloudiness with clear with two distinct separated liquids, water on bottom and fuel(ish) on top. I see bad fuel from some small gas stations kill vw's at dealer all time, can run ok with wierd sporadic misfires. If not bad fuel rec check pressure, and at least replace fuel filter.

 
AWD.FTW said:
Maybe this is true... or is damaged from ongoing issues with running. Mine died on my car, so maybe I fixed it with a hammer... funny how mine opened up after that. Also hows your fuel filter, HAS CAR SAT LONG? If it has E10 fuel and sat longer than 2 months on one tank with no stabilizer than possible that water separating out of your fuel (killed my dads snow sled (until flush tank) 2 years running). take line off your filter if suspect true, see how much fuel comes out when crank (fill a clear dry soda bottle, use little hose from fuel outlet of filter), hold bottle up to light if cloudy it is no good, if let sit long cloudiness with clear with two distinct separated liquids, water on bottom and fuel(ish) on top. I see bad fuel from some small gas stations kill vw's at dealer all time, can run ok with wierd sporadic misfires. If not bad fuel rec check pressure, and at least replace fuel filter.
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good ethanol tip Jake.

car is a DD, so it don't sit much and I doubt fuel/water sludgin is the culprit. I've had real probs with ethanol fuel in my boat, which of course sits more than a DD subie.

checking fuel filter is something I haven't done yet. guess it's time. and adding a dab of Techron fuel treatment may lick them probs anyway.

...and the the time-tested hammer on the cat trick, yah, that'll be theraputic for sure. good reminder, tanks!!

 
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Yup just thought I would mention fuel cause it can get overlooked a lot, causing parts chucking. Never know if a gas station got a bad fuel too. Easy to check and rule out.

Also I should mention when I "fixed" my cats creates a "hollow" sound
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, wrapped them with header wrap helped quiet them down again (wrapped were all factory shields used to be, eliminated rusty broken ones at same time)

Also if you have no fuel issue, and you have a maf I would look there closely I hear k and n filters can lead to early maf death if the filter oil get too them if you have one installed too. Lucky my 01outback is federal emissions model with none.

 
Mikey already mentioned his was map sensor based. Po420 is for the secondary o2 sensor in the exhaust, but the actual fault in the ecu shouldn't cause problems, only the mechanical fault that it detects.

Is that the only code? Does that year detect misfires? Maybe do a compression check...

Thought I would list that since it hasnt been mentioned yet.

Good luck dave.

 
This may sound stupid, but make sure your spark plug wires are fully seated. One of mine wasn't pushed in enough for the rubber to seal to the valve cover, and I'm not sure if that cylinder was even firing. I guess it depends how far the contact goes within the wire.

Anyway, I had no CEL (yes the light works) and it does make some sense that this unevenness would be felt in the car.

 
drvsdwz said:
Mikey already mentioned his was map sensor based. Po420 is for the secondary o2 sensor in the exhaust, but the actual fault in the ecu shouldn't cause problems, only the mechanical fault that it detects.

Is that the only code? Does that year detect misfires? Maybe do a compression check...

Thought I would list that since it hasnt been mentioned yet.

Good luck dave.
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Missed that on the maf.
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Front o2 def issues there can cause mixture woes, front o2 important for driveability.

P0420 is usually "catalyst efficiency below threshold bank 1" which indicates the catalyst material is not functioning withing permissable range for effective emissions, this can be due to the cat itself being used up, plugged etc, or the engine running poorly enough that cat cannot correct the levels of NOx, CO, and such to a point which is withing tolerances specifically for emissions (bad front o2, misfire can idirectly cause false bad cat test). Secondary o2 sensor issue itself would be its own fault such as is persistant in my car, and not affect driveability at all. Agree that if cannot isolate o2, spark, fuel, cat, compression test may be necessary with no other issues found.

 
def do a compression check, check the plugs health while you're at it. A good carbon cracked plug could do it.

could also be a POOP coilpack or a crank/cam position sensor gettin' funky on ya

being an internet mechanic is fun!!!

 
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