I failed emissions. What do the #'s mean and what can i do?

[Vicarious]

Yea i failed emissions today. NOx is 2909, and says standard is 1134. HC is 178 and standard is 146. I got a '91 318is, M42 block. I just bought the car a few weeks ago so still dont know much about it. It needs a new valve cover gasket, which I ordered and gonna install as soon as it comes. The exhaust was redone by the previous owner and looks pretty good and pretty new.

Do those solvents really work? like guaranteed to pass or somethign.

[NC325iC]

looks like its running a little rich to me, have you tried to pull any check engine codes?

[Vicarious]

nope. dont got a code tool. Im gonna wait for the gasket to come in, do that, change the plugs, give it an oil change, then drive the shit out of it before i go back. It was also really hot today.

[kellie]

looks like its running a little rich to me, have you tried to pull any check engine codes?

High NOx is an indication of a LEAN condition, along with high O2. High Co would indicate a rich condition, and high HC indicates a misfire. OP, please post ALL of the numbers and the RPMs.

[Vicarious]

ok.
NOx: 2909
HC: 178
CO%: .64 (Pass)
CO2%: 13
O2%: 1.1
RPM 0.

This is exactly how it looks on the print out he gave me. This is NJ inspection by the way.

[kellie]

I'm a little rusty on my emissions analyzing, but everything looks pretty normal. I'd definitely check for vacuum leaks even though your O2 doesn't look terribly high. Change the oil, fill up with a fresh tank of premium gas, change your plugs, try a can of seafoam to clear out carbon, and try again. I'm not sure if the ignition timing is adjustable on our cars, but if it's overly advanced, that could also cause high NOx.

[NC325iC]

guess your smarter with emmisions than i am, last time i failed my HC was in the 300s, o2 sensor replaced fixed it, that was my last emmisions inspection

[dark89e30]

Rule of thumb, a new cat will make the car pass almost every time. Try pouring a bottle of isoprophyl alcohol(99%) in your tank, thats all that the smog pass additive is anyway, and that will raise the fuel octane and help drop the nox. With how abnormally high the nox is, and since your C02 is awsome, I can almost guarantee that the cat is bad anyway.

[Vicarious]

Yea, i need to change the valve cover gasket, when i do that i'm also chanign the spark plugs, and putting in new oil. Plan to drive the shit out of it before i go back to take the test again. Should be fine right? I'll try the iso alcohol, but if your saying that my cat is bad anyway, then would those things even do anythhign?

[NC325iC]

i doubt those things will do much of anything to help your scores, but thats just me

[dark89e30]

Those things alot will definitely drop your nox and but I think that you will be lucky to pass. But I you don't have the $150 for a new cat, I might be worth trying for $20 for a retest.

[Vicarious]

since when are cats $150? i found $80 ones on jegs or summit. I think im just gonna get a new cat. Mine sounds like someone dropped a penny inside.
Anyone know what best size dimensions to go with for a cat for a 318is? I know its 2.25 in/out, what about length? Does it matter if its oval or sound? Whats the deal with the air inlets? and whats the diff between 2-way and 3-way.

[dark89e30]

2 way gets rid of HC and CO and the 3 way adds NOX elimination. 2 way cats are outdated.

[thereisnoyun]

cat is last

Check the most important sending units to make sure its functional

- ignition - wire, coil
- vacuum leak
- throttle adjustment
- temperture sending unit
- o2 sensor

these are the top things that screw up emissions. Then seafoam the car and get g2p and you'll pass even with bad cat, unless its totally melted.

[Vicarious]

Ok i got tested again a few weeks ago, and although the numbers are a little better, they are still nowhere near passing.

All i did was new sparks, oil change, taped upu some vaccum cracks because i couldnt get new hoses in time, had to order.

here are the #'s now:

NOx: 2572
HC: 167
CO%: 0.75
CO2%:13.8
O2%: 0.9

I was thinking of doing Seafoam, get the vac lines finally. I can't realy afford a new O2 sensor at the moment. And plus the exhasut part from the headers to the cat looks new, so does the cat. Could it be possible that whoever did the exhaust reused the O2 sensor? I can't really afford one, theyre like $100.