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Guest jclay

Shot o2 sensor? please diagnose...

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Guest jclay

O.K, pursuant to several previous posts, i can't pull coded because of a burned out CEL. I've tried and failed to fix it, so i need everyones help to try to determine what it may be. I suspect the o2 sensor, but appreciate all income...

 

The symptoms:

 

Drastic loss of fuel economy-down to around 8 (yes 8) MPG's

Extremely rough idle.

Occaisional dips and surges in power while driving

Constant loss of power in general

regular stalling when not warmed up.

occaisional smell of gas while idling, regular smell of gas when leaving the car after stopping

 

its a 94 legacy gt, all help is greatly appreciated.

 

jared

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How many miles on the current sensor?

 

I would fix the light first before doing anything. Sounds like it may be the coolant temp sensor ("choke" is always on).

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My experience is with older Subarus, but a bad/disconected (broken wire) sensor never sent things that south. I would imagine it would just run in an open-loop mode, maybe just slightly rich. I wouln't think that the variation allowed for O2 signal would be great emough for your problem. Where is the smell of gas? Back of car, engine compartment? Black smoke?

 

If engine compartment smell and no/little smoking, I would go for a leak... fuel leak, that is. If exhaust-pipe smells and smoke, maybe leaking injector or the CTS or one of the other air mass/flow sensors used on the Legacy.

 

my $.02

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Guest jclay

yeah, the dealer wants @ $200 to fix the light, i just may have to bite the bullett...

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Here's my experience w/ O2 sensors;

 

My buddy's '95 outback SW had similar, not as severe symptoms, including (it was a 5-speed) a complete innability to rev over 2.5 or 3 k.

We popped the hood, and there was a little hose on the left side of the engine (right on the surface) that had been disconnected, was a 1/4" black rubber thing. we plugged it back in, and it ran as expected.

 

Now i don't know the engine differences, but this is something to check, if it's just the little hose. i'm also not 100% that this was an O2 sensor, but that's what we figured, and the symptoms went away.

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I would get fixed it ASAP. You probably have raw gas washing down your cylinder walls. After the raw gas removes the absolutelty critical lubrication from your cylinder walls, it ends up in the sump where it dillutes your oil. The unburned gas that makes it out your exhaust valve is probably putting your cat into hyperdrive, if it's still working.

You can pay $200 dollars now, or you can spring for an engine rebuild or replacement a month or so from now. Some car repairs you can let go for a while, this is NOT one of them.

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Hi,

try the simple things first, aircleaner, sparkplug colour, vacum pipes. The dealer should be able to test the O2 sensor and get your codes out using a scanner for a few dollars which will be a lot cheaper than fixing the CEL.

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Or autozone will read the code and reset the CEL for free.

 

Todd

 

Hi,

try the simple things first, aircleaner, sparkplug colour, vacum pipes. The dealer should be able to test the O2 sensor and get your codes out using a scanner for a few dollars which will be a lot cheaper than fixing the CEL.

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My O2 sensor is shot (and unplugged) in my 90 legacy. I get crappy gas milage, exhaust stinks and it runs like ARSE! I just wish they weren't so darn expensive. $85.00! AARRRR!!

 

My cat is hollow so I am not too worried about it clogging up again. HEHE!!

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