help me figure out why im not passing smog

[jefffribourg]

here is a copy of the paper that i got after i failed my smog test


this is for california. the guy at the shop was trying to tell me that the reason why im not passing is because of my K&N air filter and that it should be down by the bumper and right now its located behind the driver side high beam. also he was saying some things like its causing me to waste fuel and that its making my car run hot. idk if its just the air filter or what but if anyone can look at the paper and give me any advise on how i can go about passing the smog test that would be great.


thanks. jeff

[Cabriolet]

is that a bad O2 sensor or a vacuum leak?

[superultrahippo]

You're going to need to provide a bit more info if you expect any real help. Any recent repairs? Your NOx is pretty high and so are your HC's. At 200k miles a new cat will help your nox readings. HC is a result of unburnt fuel. Make sure you dont have leaking injectors. Replaced plugs if not recently serviced. Once you get your hc reading down, your CO(partially burnt fuel) will follow. Seeing as it wasn't THAT far off, it should get you in passing range. A weak spark from worn cap/rotor will also up these readings. Visually inspect those items.

Some tips to help you pass..
-change the oil before smog.
-get the vehicle to operating temp(run it hard and allow little down time with engine off before smog)
-some people swear by SMOG additive's.. (i've never tried em)

[superultrahippo]

is that a bad O2 sensor or a vacuum leak?

A vacuum leak will DEFINITELY up your NOx as it leans out you a/f ratio. Look into that buy spraying some brake cleaner on throttle body/any vacuum or crankcase source.

[jefffribourg]

Thanks guys. im gonig to do an oil change this weekend as well as putting on the stock air box and possibly changing the plugs. while im at it ill stray for leaks.

thanks again, jeff

[foglght]

A vacuum leak will DEFINITELY up your NOx as it leans out you a/f ratio. Look into that buy spraying some brake cleaner on throttle body/any vacuum or crankcase source.

Intake leak could cause high NOx, but if it was running lean, HC levels would be low.

high NOx like that could be a multitude of problems.

High combustion temps cause NOx. If you don't have those, it could be that the converter no longer has the efficiency it once had.

Higher compression can cause the high combustion temps, so a compression test could rule that out.

Improper spark advance can cause it as well.

Does the car run hot?

I suppose if the car was chipped it could be richening out the mixture and advancing timing, which would cause both the problems.

I highly doubt a K&N filter is causing the problem.

This would be way easier to diagnose if you knew the pre-cat measurements. Converter efficiency would tell the story. I would definitely recommend making sure the car has run for at least 15-20 minutes solidly before going back in to take the test. I would not reccomend running the piss out of it though.

[delatlanta1281]

Wait, BRAKE CLEANER? I wouldn't use brake cleaner if I were you, it's a bit too combustable, how bout a little carb cleaner instead. Am i completly off base here?

[tonywonder]

go to castros shop in north hollywood. they do smog there and they know the cars well so they can probably tell you whats really wrong.

[Naplm00]

Wait, BRAKE CLEANER? I wouldn't use brake cleaner if I were you, it's a bit too combustable, how bout a little carb cleaner instead. Am i completly off base here?

not really, I use either...never seems to matter

[jefffribourg]

Does the car run hot?

I suppose if the car was chipped it could be richening out the mixture and advancing timing, which would cause both the problems.

the car was running hot yesterday after i took it in which was weird because ihad to stop and let it cool down after the testing. But before the testing and a few hours later it was running perfectly normal. it ran perfectly to work this morning and perfectly yesterday in the afternoon when i had to run errands for work.

i do know that the car is chipped but i dont know what chip it is though because it came with the car when i bought it. i know that i have to run 91 with it.

how do i do a compression test? would i need to take the car to a shop to be done?


To do list
- oil change
- spark plugs
- check for intake leak/ possibly put on stock intake

[s0urce]

Forget why you're failing...

Here's how you pass:

Hollywood Test Only Station
1787 North Highland Avenue
Los Angeles, CA 90028-4403

(323) 462-2764

Ask for arvin, tell them Chris sent you and said you guys could help him out.

[foglght]

the car was running hot yesterday after i took it in which was weird because ihad to stop and let it cool down after the testing. But before the testing and a few hours later it was running perfectly normal. it ran perfectly to work this morning and perfectly yesterday in the afternoon when i had to run errands for work.

if it was running hot and it is chipped, there could be your answer.

i do know that the car is chipped but i dont know what chip it is though because it came with the car when i bought it. i know that i have to run 91 with it.

So, it definitely advances the timing. How much, who knows, but chip manufacturers (unless carb legal) do not usually consider the greater emissions by changing the tune.

how do i do a compression test? would i need to take the car to a shop to be done?

It's actually pretty easy, though you will need to pick up a compression gauge. You can do this at the same time you do the spark plugs. I'm not as familiar with the E30, but typically you take the spark plug out, thread the compression gauge fitting in, tighten it down, and rotate the engine until the gauge jumps up. Some car manufacturers tell you to test with the engine cold, some with it hot.

If you do it by cranking the engine, you'd need to disconnect the fuel injector for each cylinder that you are testing so you don't get fuel mixed in there, which can throw off the readings.

Also, maybe check another shop. The analyzers that measure the ppm in the exhaust are very touchy. Every test bench here at work has a separate analyzer for HC, CO, NOx, CO2, hexane, and CH4. We have 3 benches per test cell. Each one of those analyzers has to be calibrated before every test. Along with that, the measurement curve for the analyzer needs to be re-run about once a month.

The analyzers are pretty sensitive and any localized contamination can screw up results as well......like another car running nearby, or lingering constituents.

I hope you get this narrowed down. Typically, we will run a 15 minute warmup before each test. The catalyst even after 5 minutes of warmup still isn't fully up to optimal temperature.

[jefffribourg]

s0urce:
ill check out that shop and let them know that you sent me, thanks a lot!

foglght:
when they tested my car they did it all at one station and it was a small shop to begin with that had other cars running.... there was a car right next to mine that they were reving that was practically painting the floor black with the shit that was coming out of the exhaust. they also spent more time looking in my engine bay at the air filter then mostly anything else. they didn't let the car warm up really and did the test in about 15 minutes after getting i onto the stand. during one of the tests the guy also walked over and took of my gas cap if that has any significance at all. now that i think about it the shop really smelt like exhaust and a few guys were smoking in the shop so it might not have been the best place to get the smog done at.

[foglght]

Well, looks like you just need to take it to a different shop then first before you start dumping money at a problem you might not even have.

Good luck!

[Jon325i]

I just completed going through the Calif smog two-step last week. My car, '91 325i w/ 207K miles, was a borderline fail/gross polluter in 2008, but passed with room to spare this year. Prior to this recent smog test I did the following....

1. Thoroughly go through the intake system (new air filter, remove AFM and cleaned it out with some CRC brand MAF cleaner, checked all intake path hoses/tube for leaks, checked all hose clamps, cleaned around the throttle body path....didn't remove it from the engine, but made sure the air flow path was clean & tidy)

2. All vacuum hoses were checked over for any potential leaks...fortunately none found (tubes are in good shape, no cracking)

3. New ignition components installed (cap, rotor, plug wire harness, spark plugs and coil)

4. New 02 sensor installed

5. 1 can of BG brand 44K fuel treatment in the tank (pour in with a 1/4 tank of fuel, run until empty, refill tank completely)

6. 1 can of CRC brand Guaranteed To Pass syphoned through a vacuum at the intake (you're supposed to put this stuff in the tank and mix with gas, I did the super concentrated technique)....then drive car for 30 minutes afterwards. Lots of white smoke - much like doing SeaFoam treatment.

7. Change motor oil and filter

Now the catalyst on my car is an aftermarket/universal piece a local shop installed 35K miles ago, but I ran a test pipe in its place for a while so there's probably 20-25K miles of actual use on it now. What you must keep in mind is that our cars are heavily dependent on a good condition catalytic converter and 02 sensor in order to pass an emissions test. But those aren't the end all/be all to the solution. I would definately look into components in the ignition system. Spark plugs definately - cap & rotor? Perhaps....depends on the age/mileage of them. Vacuum leaks can be a problem too. You can get some replacement universal hose for the smaller ones at Kragen or AutoZone for cheap. Definately have clean oil in the motor and make sure your clutch fan assembly is functioning properly too. If it isn't cooling your motor sufficiently, too hot of an engine can give bad readings as well.

Lastly, take it for solid 30 minute drive before going in for your smog test - get on the freeway running in 3rd & 4th gears. In the past, I've timed it so that I arrived at the shop w/in 30 minutes of closing when no other customers were having their car tested. This allowed my car to be placed on the rollers and tested right away before anything had a chance to cool down. You would be surprised how much a catalytic converter can loose its prime operating temp in a short amount of time.

One last point: before you have another test run, talk to the technician at the smog testing facility and see about having a pre-test done. The place I went to did this for $20....basically ran a "test" but didn't send the final readings to the DMV electronically. You can get a printout of these results and figure out if the repairs you made are on target to getting your car to pass the real test.

Jon