Hi All,

Just failed :mad the Connecticut emissions test in my '94 530i. Here are the readings:
HC - 75 PPM (Limit 100)
CO - 0.73 % (Limit 0.53) FAIL
NOx - 443 PPM (Limit 1167)
RPM - 2316

The car passed 2 years ago. Here are the readings:
HC - 21 PPM (Limit 100)
CO - 0.02 % (Limit 0.53)
NOx - 161 PPM (Limit 1167)
RPM - 1769

All scheduled maintenance has been done (oil changes, air filter changed, etc)

What can I do to fix the car or do I need to take it to the shop/stealership for them to look at?

Change your plugs and get a new O2 sensor and go from there.

Mine failed a long long time ago. They never pulled the plates though.

I'm in Cheshire, where are you located? If you need a hand PM me.

You are very close and probably nothing is too wrong. How old are the spark plugs, air filter etc? Do you run fuel injector cleaner. If the plugs are more that 25-30k miles old - I'd do those, run injector cleaner and take iit out on the highway and really blow it out before restest (also check for air leaks).

New plug at 114K - now at 135K, I'll be putting new ones in tonight.
Air filter and oil done just 2 weeks ago. As alway full synthetic.
Will also run a bottle of injector cleaner through it and cruise the highways.

dont cruise the highway, blaze the highway, really drive it hard, then take it imedietly to the emmisions testing, hot cats=pass

my exhaust smells like crap im probably getting new O2 sensors soon :)

The smell is just sulfur in your gas, (like the kind that ruined the Alumasil engines) - although the cost of gas is going up - the quality is going down. You O2 sensors and cat are probably doing their job of reducing NOx when you smell rotten eggs (H2S) as you need to go from reducing to oxidizing conditions with the lamda loop for your 3-way cat. to work correctly. Refineries can only remove a set nunmber of tons of sulfur per day from the fuel stocks, the rest has to end up somewhere. Higher sulfur crude will result in more sulfur in your gas (unless you live in California) - new diesel rules could also mean more sulfur in gasoline.

I thought H2S smell was the sign of a failing cat? I have a caprice that burns oil due to leaking valve seals and a lazy owner (me). The oil fouled the O2 and cat to the point where the smell was intolerable (and performance bogged).

Fortunately here there is no testing and any vehicle older than 15 years can have emissions equipment removed legally so cat gone, problem gone.

The smell is just sulfur in your gas, (like the kind that ruined the Alumasil engines) - although the cost of gas is going up - the quality is going down. You O2 sensors and cat are probably doing their job of reducing NOx when you smell rotten eggs (H2S) as you need to go from reducing to oxidizing conditions with the lamda loop for your 3-way cat. to work correctly. Refineries can only remove a set nunmber of tons of sulfur per day from the fuel stocks, the rest has to end up somewhere. Higher sulfur crude will result in more sulfur in your gas (unless you live in California) - new diesel rules could also mean more sulfur in gasoline.


u meen the nikosil block the alusil is the one u want. :redspot

Put a bottle of Gumout Fuel System Cleaner through the system and changed the spark plug and had the car retested after burning up the highway for a good 30 miles and here are the results:
HC - 82 PPM (Limit 100)
CO - 0.53 % (Limit 0.53) PASS:cool
NOx - 465 PPM (Limit 1167)
RPM - 2185

I'm still going to change the O2 but at least it meets the minimum for getting the registration renewed. Still why would the HC go UP???:confused

I thought H2S smell was the sign of a failing cat? I have a caprice that burns oil due to leaking valve seals and a lazy owner (me). The oil fouled the O2 and cat to the point where the smell was intolerable (and performance bogged).


Fortunately here there is no testing and any vehicle older than 15 years can have emissions equipment removed legally so cat gone, problem gone.


Hey, great you passed! Nilosil - yeah - oops - failed because of the high sulfur (largely unreported and unsuspected by our trusting friends in Bavaria) in US gasoline.


Oil has lots of sulfur compounds (like gear lube), continous rich operation overheats the cat and exacerbates the rotten egg smell. Tampering with pollution controls is illegal and not something I would admit to on a public forum.

i have this rotten egg smell after letting the power loose. what would i need to change maby O2 sensors, new cats.

Put a bottle of Gumout Fuel System Cleaner through the system and changed the spark plug and had the car retested after burning up the highway for a good 30 miles and here are the results:
HC - 82 PPM (Limit 100)
CO - 0.53 % (Limit 0.53) PASS:cool
NOx - 465 PPM (Limit 1167)
RPM - 2185

I'm still going to change the O2 but at least it meets the minimum for getting the registration renewed. Still why would the HC go UP???:confused

High HC is usually a sign of a misfire so you may have a coil or two going south. If your NOx was off the charts high then that is a sign of lean conditions or extreme carbon build up leading to knocking/pinging - which you dont appear to have. Appears to be either a rich condition (misfire, leaking injectors etc) or vacuum leak post MAF which is limiting the ECU's ability to get spot on air/fuel mixtures and the car is running rich as a result.

HTH,
G

Today, I just failed also on my 93 525iT (which passed 2 years ago):

HC - 115 PPM (Limit 120)
CO - 0.76 % (Limit 0.64) FAIL
NOx - 0 PPM (Limit 1400)
RPM - 1817

I don't think I ran the car hot enough before inspection. How could my NOx be 0 PPM? I have also been using Plus gas rather than Premiun Gas, would this affect the CO? Thanks for your input. I hate this emissions stuff as it is so nebulous!

You want a balance between rich and lean operation - ultra low NOx and high CO and HC means your car is not looping between rich and lean and hanging around the more on the rich side. Could be the O2 sensor, FPR, coolant temp sensor, MAF air temp sensor, leaky injectors - you could search for a list of things that might make it run a bit rich. Its not way off or your numbers would be worse - running a bit rich is not good for fuel economy either. Bentleys can help you test these things - injector cleaner and good turnup never hurts. More ethanol in the fuel will help lean things out also.

[quote=edgedude;13009777]Today, I just failed also on my 93 525iT (which passed 2 years ago):

HC - 94 PPM (Limit 120)
CO - 0.79 % (Limit 0.64) FAIL
NOx - 0 PPM (Limit 1400)
RPM - 1890

So I changed the spark plugs with OEM Bosch copper plugs and ran it on the highway at 5000 rpms for 8 miles before testing. I got my HC # down from 115 to 94 but I failed the CO #. The guy said the CO is too high and that I needed a new catalytic converter. Is he right, how can I get my CO # down?

Today, I just failed also on my 93 525iT (which passed 2 years ago):

HC - 94 PPM (Limit 120)
CO - 0.79 % (Limit 0.64) FAIL
NOx - 0 PPM (Limit 1400)
RPM - 1890

So I changed the spark plugs with OEM Bosch copper plugs and ran it on the highway at 5000 rpms for 8 miles before testing. I got my HC # down from 115 to 94 but I failed the CO #. The guy said the CO is too high and that I needed a new catalytic converter. Is he right, how can I get my CO # down?

It would appear from your numbers that you have a misfire resulting in high amounts of hydrocarbons (both HC and CO) remaining post cat. Does the car get good mileage still? How old is the O2 sensor and coilpacks? Does the car roun rough/stumble at all during warm up? If you have a leaky injector or bad vacuum leak that could also be a contributor to your problem.

I believe your cat is still working as it appears (from your numbers) to be using up all the O2 coming into the engine and converting all unburnt fuel with that remaining O2 to CO. It still had fuel left over that it could not convert fully to CO2.

Did the test also give you CO2 and O2 results? If you know the O2 results that will help analyze if all the oxygen is getting used up for combustion and can help isolate rich/misfire and rule out any potential for lean burn conditions. If you have O2 remaining in tailpipe then you have a more complicated problem to diagnose.

OT - organic and advanced biochemistry does get some use later in life. :D