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Discussion Starter · #1 ·
Hey all...
Perhaps someone here can help me out. I just had both oxygen sensors replaced on my car (a 97 Accent SOHC) after the check engine light came on and I had the codes pulled from the ECU. Before I had the work done, the car was using a lot more gas than usual (because of the faulty O2 sensors, I assumed, as the ECU wasn't getting the correct info to regulate the fuel flow). But it hasn't gotten any better since, and in fact almost seems to have gotten worse. I've driven a little more than 1,000 km (~600 mi) since the sensors were replaced and the check engine light hasn't come back on, at least not yet.
Has anyone else had fuel economy issues with their Hyundais, and specifically with an Accent? <img src=/images/forums/snitz/disapprove.gif width=15 height=15 border=0>


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Edited by - cdchase on 02/04/2002 06:31:48 AM
 

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If BOTH 02 sensors were bad for a long enough period of time, you could have carbon/soot build up everywhere. Valves, exhaust maifold, clogged cats...etc..etc..etc..

Start running "premium" gasoline for the next few fillups, and also try to bring the engine all the way up to redline. This will start to eat up/blow out the carbon build up.

Pull your spark plugs. Clean them off with a wire brush, or just replace them with new Copper plugs. The plugs are probably fouled with carbon.

That should help you. If the above does not, your cat/cats may be clogged and need to be replaced.


<hr width=60% noshade size=1 align=left>quote from 4DoorGL: "Told you. Random is cool as hell in person, even if he is a dick on the net <img src=/images/forums/snitz/wink.gif width=15 height=15 border=0> (j/k)"

Leave it to Random to Needlessly complicate things.
 

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Discussion Starter · #3 ·
Thanks for the reply, Random. The plugs were replaced at the same time the O2 sensors were. Your suggestion about the cat is just what I was afraid of hearing. It doesn't feel like the cat is clogged at all, though I don't know if that would necessarily happen in such a short period of time. The car still has good power, and the engine is not running hotter than normal (which, I believe, would indicate an obstruction in the exhaust).
If the cat was clogged or damaged, would that not throw off the readings of the upstream and downstream O2 sensors? The check engine hasn't come back on, and I've driven almost 1,200 miles (1900 km) since the O2 sensors were replaced.
And to paraphrase your signature, I would say, "leave it to OBDII to needlessly complicate things!"
Thanks a bunch for your suggestions,
Chris.



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If the cat(s) were just minorly clogged, it would create exessive backpressure. That would rob you of HP and mileage, but not throw a CEL, as it would still allow the cats to function.

There are several brands of "cataylitic converter cleaner" on the market. You MIGHT want to consider giving one a shot. That would be much cheaper than outright cat replacement.

Lastly...I can't see where you live, but if you live where they change the "winter gas" to an oxgenated gas, that can cause the decrease in mileage, and it can also cover up a failed cat. Once your gas pumps go back to "summer gas" your CEL might come back on, to indicate your cat(s) as bad.


<hr width=60% noshade size=1 align=left>quote from 4DoorGL: "Told you. Random is cool as hell in person, even if he is a dick on the net <img src=/images/forums/snitz/wink.gif width=15 height=15 border=0> (j/k)"

Leave it to Random to Needlessly complicate things.
 

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Discussion Starter · #5 ·
I live in Ottawa, Ontario, Canada, and yes, the gas stations do switch to winter fuel, so that is a distinct possibility.
I haven't noticed any loss in power and the car is running as well as it ever has. I'll take a look around for some cat cleaner. Is it sold at auto parts and supply stores? I've never seen it before, but I've also never looked. Would it be similar to that stuff that claims it will make your car pass a smog/emissions test?
Thanks again for the suggestions,
Chris.


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It would be in the "gas additives" aisle. (Octane boost, fuel injector cleaner...etc.etc.)

It should be labed as "Cat converter deoderizer" or "Cat converter cleaner".


<hr width=60% noshade size=1 align=left>quote from 4DoorGL: "Told you. Random is cool as hell in person, even if he is a dick on the net <img src=/images/forums/snitz/wink.gif width=15 height=15 border=0> (j/k)"

Leave it to Random to Needlessly complicate things.
 

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Discussion Starter · #7 ·
I'll take a look. Thanks Random.
C.


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