new CC, carbon cleaned a month ago with B12.
Passes at 25mph but fails at 15 (very hard), any Ideas? no EGR, clean PCV.
Passes at 25mph but fails at 15 (very hard), any Ideas? no EGR, clean PCV.
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Stumped - Smog
- Thread starter Sepultura
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Other possible causes listed in the local Aircare manual:
excessive spark advance
lean air/fuel ratio
O2 sensor malfunction
cat converter malfunction
faulty thermostatic air cleaner
defective air flow meter
excessive spark advance
lean air/fuel ratio
O2 sensor malfunction
cat converter malfunction
faulty thermostatic air cleaner
defective air flow meter
What make/model car?? What miles?
Sepultura
Thread starter
1993 civic 175,000.
spark advance would be timing right? the guy said it was at 17, but it would not really change anything either way when it's that high.
lean air/fuel would be due to timing?
O2 is a year old
no idea what those last 2 are or where to check them, it just seems very odd that the NOX would be THAT high at 15, and it's the ONLY gas that fails at any speed.
spark advance would be timing right? the guy said it was at 17, but it would not really change anything either way when it's that high.
lean air/fuel would be due to timing?
O2 is a year old
no idea what those last 2 are or where to check them, it just seems very odd that the NOX would be THAT high at 15, and it's the ONLY gas that fails at any speed.
13+ year old converter, eh? Bet it's tired, and can no longer clean up NO at leaner running conditions. The tip-off is the still relatively high NO reading at the 25-mph speed shown on your results (when you'd be deeper into the throttle and presumably running richer).
You can probabably find a new bolt-on three-way converter at Kragen (Meritor probably makes one). If the '93 Civic is anything like my '83 was, the converter has flanges at each end secured by three bolts to the rest of the pipe.
TIP: If the converter *is* a bolt-on, TIGHTEN (yes, tighten) the nuts first, and THEN loosen them. You can avoid breaking a nut or bolt this way. Some PB Blaster would do well here if you have any.
Once you've passed your smog (and you will), you can simply remove the new converter and bolt the old one back on. Stash the new one in the rafters for two years down the line, when you'll have another opportunity with the CARB folks.
Use some high-temp anti-seize on the bolt threads so you can get the converters off easily each time, too.
You can probabably find a new bolt-on three-way converter at Kragen (Meritor probably makes one). If the '93 Civic is anything like my '83 was, the converter has flanges at each end secured by three bolts to the rest of the pipe.
TIP: If the converter *is* a bolt-on, TIGHTEN (yes, tighten) the nuts first, and THEN loosen them. You can avoid breaking a nut or bolt this way. Some PB Blaster would do well here if you have any.
Once you've passed your smog (and you will), you can simply remove the new converter and bolt the old one back on. Stash the new one in the rafters for two years down the line, when you'll have another opportunity with the CARB folks.
Use some high-temp anti-seize on the bolt threads so you can get the converters off easily each time, too.
My apologies, Sep -- you already have a new converter.
Aftermarket or OEM Honda?
It would seem that your car is running lean. Check your plug readings as a start.
Aftermarket or OEM Honda?
It would seem that your car is running lean. Check your plug readings as a start.
Sepultura
Thread starter
Aftermarket, magnaflow.
Will check my plugs, how do I make it run richer? how much richer would it need to be in order to overcome that massive NOX output? you're probably right about since CO is a byproduct of combustion and mine is low, REAL low so that means it isn't combusting, therefore it's running lean. Thanks for everyone's help, keep it coming.
Will check my plugs, how do I make it run richer? how much richer would it need to be in order to overcome that massive NOX output? you're probably right about since CO is a byproduct of combustion and mine is low, REAL low so that means it isn't combusting, therefore it's running lean. Thanks for everyone's help, keep it coming.
For self help try - Your advance is probably right as its part of the CA test.
www.recarbco.com/technical/smog/smoginfo.html
www.recarbco.com/technical/smog/smoginfo.html
With that mileage -
my quess is NOX is a by-product of too high of combustion temp. A very common cause of high temp is effective compression ratio. Carbon! If you've formed lots of carbon due to oil consumption through the valve guide seals- you may be too hot. Cure is to decarbon the system.
Other causes - vaccum and exhaust leaks, egr plugged - carbon again.
my quess is NOX is a by-product of too high of combustion temp. A very common cause of high temp is effective compression ratio. Carbon! If you've formed lots of carbon due to oil consumption through the valve guide seals- you may be too hot. Cure is to decarbon the system.
Other causes - vaccum and exhaust leaks, egr plugged - carbon again.
If you're running too hot - either with air leaks
or high compression that the test won't allow you to adjust timing for then take the the plugs out to lsee if they are too hot eg white , elements even melted. See some plug charts.
When was the converter changed - I only see O2 changed.
or high compression that the test won't allow you to adjust timing for then take the the plugs out to lsee if they are too hot eg white , elements even melted. See some plug charts.
When was the converter changed - I only see O2 changed.
Sepultura
Thread starter
converter was changed earlier this week, i did B12 through the intake about a month ago.... about a whole can, any other way ?
car came without an EGR, which is odd, maybe it is one of those cars that was not meant for cali. I have read that you (original owner) must pay a smog fee and the vehicle now has to only meet federal standards, no idea how to find out if my vehicle is one since the underhood label is missing dude to hood replacement before i got it.
CO2% is fine which indicates combustion (not lean), HC is below average (not rich), but CO and O2 (oxygen?) are low, what does that mean?
unless im mistaken, islavistaman?
maybe i should just bring a big ice chest next time and let my oil pan sit in ice water while they do the test? lol..
car came without an EGR, which is odd, maybe it is one of those cars that was not meant for cali. I have read that you (original owner) must pay a smog fee and the vehicle now has to only meet federal standards, no idea how to find out if my vehicle is one since the underhood label is missing dude to hood replacement before i got it.
CO2% is fine which indicates combustion (not lean), HC is below average (not rich), but CO and O2 (oxygen?) are low, what does that mean?
unless im mistaken, islavistaman?
maybe i should just bring a big ice chest next time and let my oil pan sit in ice water while they do the test? lol..
I'd guess vaccum or exhaust leaks and smoke test to find them. CA cars get cooked in 173K miles.
You can retard timing within the allowable range of maybe 2-4 degree and that will get you maybe 100ppm off for each degree while increasing HC. I don't see enough room on timing to solve your over NOX and still pass the timing check part of the test. Look on the hood for timing info for timing decal to see if you can change it and retard it.
You can retard timing within the allowable range of maybe 2-4 degree and that will get you maybe 100ppm off for each degree while increasing HC. I don't see enough room on timing to solve your over NOX and still pass the timing check part of the test. Look on the hood for timing info for timing decal to see if you can change it and retard it.
One easy way to make an engine run richer is to simply plug up the intake. BTDT twice in fact, to get the NO down.
You'll have to experiment with this, of course. See if you can find a place in the airbox where you can securely tape off a section (something like duct tape and cardboard will work) and reduce the air flow. You might try taping off the whole thing and then punching five or six holes in it with a pencil, to start.
Crude, but effective -- but that's the idea. You've got a lot of room to work with in regards to higher allowable HC. Bring the car to a somewhat boggish state (it should idle okay, but have no power), take it in, and get another reading. NO should drop dramatically and HC rise. Your car doesn't have to run perfectly to pass smog, after all.
All you're looking for is that balance point that will let you pass.
Make sure your temporary (did I say that?) "smog repair" isn't visible to the tester, of course.
You'll have to experiment with this, of course. See if you can find a place in the airbox where you can securely tape off a section (something like duct tape and cardboard will work) and reduce the air flow. You might try taping off the whole thing and then punching five or six holes in it with a pencil, to start.
Crude, but effective -- but that's the idea. You've got a lot of room to work with in regards to higher allowable HC. Bring the car to a somewhat boggish state (it should idle okay, but have no power), take it in, and get another reading. NO should drop dramatically and HC rise. Your car doesn't have to run perfectly to pass smog, after all.
All you're looking for is that balance point that will let you pass.
Make sure your temporary (did I say that?) "smog repair" isn't visible to the tester, of course.
Sepultura
Thread starter
just visually check for cracks? it looks pretty rusty, but how would a crack change nox? wouldnt a crack allow for exhaust out instead of going down the pipe to be picked up and actually help me?
Sepultura
Thread starter
what about maybe the MAP sensor?
Your right on the exhaust crack - that would make the o2 sensor overcorrect and fail hc.
Propane torch w/o lighting it will find you some of those intake leaks as the car rpm will speed up if you want to home test for some leaks on intake.
Propane torch w/o lighting it will find you some of those intake leaks as the car rpm will speed up if you want to home test for some leaks on intake.
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Well, the guy was FOS. That's how I got my minivan to pass NOX. The CO and HC were in the basement. NOX high. Turn the distributor back ...PASS. That's the only thing to control NOX without an EGR ..that and cam overlap.quote:
Originally posted by Sepultura:
1993 civic 175,000.
spark advance would be timing right? the guy said it was at 17, but it would not really change anything either way when it's that high.
If your timing is adjustable ..there is where you need to look.
Sepultura
Thread starter
islavistaman - good idea, now if it wasn't $50 a pop id do it all day until i found a way to pass.
Gary - yes you can move the dist back and forth, however it's almost retarded all the way.
I am going to apply for that cap program thing and hopefully they can fix it for $500, if not i don't know, i hate smogging.
Gary - yes you can move the dist back and forth, however it's almost retarded all the way.
I am going to apply for that cap program thing and hopefully they can fix it for $500, if not i don't know, i hate smogging.
High NO is a bad EGR or cat.
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