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Failed Emissions OX2
Posted 17 April 2004 - 07:19 PM
Oxides of Nitrogen (NOx): FAIL
State Standards 2.2000 GPM
Inspection Reading 4.01666 GPM
What do you think could be the cause? Here are some things to look at (according to the emissions):
Air to fuel mixture too lean
Oxygen sensor not functioning properly
Inproper EGR re-circulation
Malfunction of engines spark advance
Air intake temp too high
Cooling system not functioning properly
Corbon deposits on engine intake valves
Catalytic converter partiallly clogged or not functionsing properly
Here is what I have replaced in the past few months:
Temp coolant sensor
I checked all the hoses and they are fine. The PVC is good. I ran some fuel injector cleaner about a month ago.
I heard that the "Guaranteed to pass" that they sell in the auto parts store cleans out the fuel and intake system. Is that true?
Does anyone else have any suggestions? I have read over the previous posts about emissions. Iam guessing the car is running hot. The temp gauage is normal, but the fans always run constantly. Should I replace the thermastat? Could the cat be bad? Or, too much carbon buildup? I would think that is the cats were bad and the car was running fine, it would still pass.
Posted 17 April 2004 - 11:17 PM
Posted 19 April 2004 - 02:12 AM
Posted 19 April 2004 - 01:33 PM
NOx is a result of high combustion temps. Do you know what the limits are? Do you know how far you were out?
Premium gas *MAY* lower NOx numbers, it also *may* raise the others.
No EGR on the '93. Hmm.
You might try a combustion chamber cleaner. Carbon may have built up, artificially raising the compression ratio, and causing detonation.
Posted 19 April 2004 - 01:43 PM
Run the gas down to about 1/4 tank, then put in 4-5 bottles of Heat, this is a winter gas line dryer. I have passed several cars that failed at 1st, then did nothing but this and they all have passed.
These were in Colorado, so not sure if altitude may change, or if this will work for you but cheap easy try for a fix.
Posted 19 April 2004 - 04:30 PM
Posted 19 April 2004 - 10:03 PM
Alcohol in the fuel aka HEET will lower all numbers dramatically, if enough is used. Do what rweddy suggests.
Posted 20 April 2004 - 06:10 AM
Posted 26 April 2004 - 11:07 AM
Please check out the link:http://www.letsmow.com/gold.html
Posted 26 April 2004 - 11:36 AM
i hope I don't come across as an rump roast....not in the best of moods right now.
NOx is high heat, and is typically caused when the mixture goes lean.
The 90-94 legacies do not have an EGR valve. These motors also tend to run pig rich.....so to fail on a NOx test is a huge indicator something is not right with the engine or catalytic converter.
Where did you fail the NOx test.....at idle or higher rpm? They didn't load test your car because it's AWD correct?
I would check for a vacuum leak of some sorts, and I would also be curious to know the condition of the cat converter.
If you pull the plugs out....what do they look like? If they look good and everything's normal......I'd really start wondering about the cat converter.
Subaru uses a two stage cat converter. The first converter handles reduction stages of the chemical reaction and then the second handles the oxidation stage. I'm pretty sure that's the right way.
Posted 26 April 2004 - 11:37 AM
Posted 26 April 2004 - 05:10 PM
I took off the Air Control Valve and cleaned the carbon off of it. I just replaced the plugs about a month ago. The old plugs looked fine, but the car was running terriable at that time. It was missing and hesitating very bad. What could make the plugs fail? After replacing the plugs, it runs perfect. This makes me think that the CAT's are clogged or needs to be replaced and are causing the car to run HOT? They do not smell nor sound like "rocks" inside. What do you think about the cAY cleaners they have on the market?
I do not know if this is normal, but there is alot of pressure that is released when I unscrew the gas cap. Is this normal? Could the purge seloniod valve be faulty and will that cause pressure in the gas tank?
I just replaced the thermostat the other day. I have noticed that on occasion driving at 55+ in cold weather, the temp would rise past the mid point. Then, if I would downshift or accelerate, the temp world drop past the midpoint. I thought the thermostat could have been stuck partically closed?
We have the "treadmill" test here. I have a feeling it failed at higher RPM's because two years ago they just did a tailpipe test and the car passed (the tradmill was not working at the time).
It looks like the Emissions pricing has gone up here in Maryland for failed autos. If you fail, you must show $450.00 work of receipts done to the vehicle relating to emissions. They started at $250 and keep going up and up!!
Posted 26 April 2004 - 07:21 PM
Does the CEL blink all the time even when the diagnostic connectors aren't plugged in? You may want to check out my site for more info on how to pull any codes.
Posted 27 April 2004 - 06:16 AM
The last options for me is to replace the CATs I would think. iam going to run some of the CAT cleaner through the system and then run some of the carbon buildup cleaner through. Hopefully, this will cut down on the high level.
What do you think would cause alot of gas pressure in the tank? purge valve bad?
Posted 27 April 2004 - 10:18 AM
There is bound to be vacuum/pressure in the tank......I get that hiss when I get gas.....it's not a big deal.
I guess try the cat stuff......
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