Emissions trouble on e24 in California

Dave L

Dave L

Well-Known Member
Messages
130
Reaction score
0
Location
Orange County, CA USA
I have an e24, German Euro market version (in So Cal in the US). I had been sitting for 5 months, run a few times but, not much over those five months. This week I had her all re-registered and today i took her for the the smog test. she passed just fine two years ago and this time I took to the same test center. She had a new Cat put on in 2009. The car passed all the tests except the NO test where she was triple the max at the 15 mph test (passed the 25 mph test).

The car was driven on highway, at speed for 20-25 minuets prior to the test, but that is the only driving since sometime in May.

Does anyone have any suggestions on how to get the NO numbers down to a passing level in CA? Would just driving a lot more prior to the test help? Any additives into fuel help?

Dave L
Orange, CA USA
 
You're first looking for a lean cylinder caused by an air leak, injector, manifold, etc. Can also be a spark plug wire so check for resistance. Aftermarket wire sets sometimes cause this.

Pull the plugs and look at them carefully for the cleanest one to narrow down the possibilities.

You can adjust the MAF/ AFM a bit if it's too rich.

You can using an infared thermometer read both sides of the cat, adjust the co to as equal a temp as you can.

You didn't say if the Euro was federalized with a black box and O2 sensor? If so, read the voltage off the O2 sensor and adjust and report back with the model of the ecu. Maybe the engine number will tell you if it's a "dirty" or "green" Euro.
 
emissions

It was "federalized", has all the stickers. (I've been pulled over and had them all inspected). I'm not sure what a "black box" federalized is. It has passed in CA at least ten times. It has an "059 ecu. The air leak idea sounds logical. I will take that route first and try to give it a lot of TLC prior to taking it over for a re-test.

Dave_L

My e9 is so much easier to register, since it is exempt from emissions. Maybe I'll just trade this e24 to someone for a pre-74 car ;-)
 
There was a time when some federalizers installed an O2 sensor like the US cars. Since Euros don't normally have this, they would add a box, about the size of a pack of cigarettes, to piggyback the ecu for the O2 sensor. If you don't have an 02 sensor; it's just one less item to go futzing with.
 
emissions

I have an o2 sensor, so I'll probably replace it, that should help a bit. I understand the high NO reading to be a "heat" related issue. I'll flush out all the systems, oil, coolant,, etc. change the filters, check the wires, plugs, vac lines, injectors, and we'll see what happens. I think the problem is more in that area because she sat for such a long time and because she passed the 35 mph test, but not the 15 mph.

Dave L
 
from my e30 m3 experience, if you have high NOx readings, its usually cat related. make sure that you take it in after fully warming up the engine + cat.

i presume that your CO + HC passed, which is generally more related to the general tune, condition of ecu + afm as well as o2 sensor.

you might want to post the readings under the two speeds, so that some of the professional guys might be able to give you more guidance
 
emissions

The NO readings were: at 15 mph, max was 1081, I was 3667. at 25 mph, max was 911, I was 906.

I replaced to cat at the last testing in 2009 and the car has probably been driven only a couple thousand miles (or less) in the last two years. I will be angry if it is the cat again.

Dave L
 
Dave L said:
The NO readings were: at 15 mph, max was 1081, I was 3667. at 25 mph, max was 911, I was 906.

I replaced to cat at the last testing in 2009 and the car has probably been driven only a couple thousand miles (or less) in the last two years. I will be angry if it is the cat again.

Dave L
Click to expand...

Is the cat in the same place? Modern cats are very sensitive to engine proximity due to the actual catalyst requiring very high temperatures. At low speeds, due to insufficient flow, the cat can cool down considerably.

Also, what year is the car? I'm rather suprprised that you have to get it emissions inspected at all. The normal cutoff is 25 years old.
 
Dave,

did you really warm up the car / cat prior to testing? like a spirited drive for 20 or so minutes. then test immediately, don't shut it off or allow it to cool.
 
In CA smog is required for 76 and newer vehicles, no rolling 25 year exemption unfortunately. I agree, cat has to be very hot.
 
HB Chris said:
In CA smog is required for 76 and newer vehicles, no rolling 25 year exemption unfortunately. I agree, cat has to be very hot.
Click to expand...

Seriously? Do they think the perhaps 10,000 pre-1985 vehicles left in California are going to wreck the air quality when driven occasionally at best? Then again, they did want to ban dark colors because "It forces you to use the AC more.". Talk about overstepping boundaries.

I hope that they set the emissions requirements to those of the manufacture date and not modern levels. Trying to make a nearly 40 year old car meet modern SULEV standards would be utterly absurd.
 
emissions

This current NO test standard in CA is just a few years old. I never had any issues until this NO test came into being around 2004 or 5. My car is an 85. The cat I had put on in 2009 is OEM and it is a factory set up on the exhaust system. I do need to give it some tune up TLC anyway, because it had not been driven for so long, so that will help. The drive prior to the smog test was about twenty minutes on a highway, however the smog guy was considerably late opening that morning so I was shut off for about 20 mins and then just idled in his parking lot for about ten minutes prior to the test. I'm going to do some of the maintenance items today, drive it over the next two days and re-test it tuesday or wednesday. I will post how the numbers fared at that test. I have gotten some great feedback on things to look for or tweak, so hopefully I can put it all to good use and get a low number on the re-test. I don't really have the equipment or knowledge needed to adjust any of the fuel mix, MAF, measure temperatures or any of that stuff, so I'll rely on the TLC and driving and keep my fingers crossed.

Dave L
 
Dave,

if your CO + HC numbers are fine, that's the ones that tell you whether or not you are in tune, and the injection is working properly. since you are not talking about those - she's running good. leave well enough alone. 20 minutes will chill the cat. i will give it a 90% chance thats your problem ... especially since you haven't been driving it much. you want to come right in after driving in 3rd gear at 4000 rpm for 15 or 20 minutes ... and go right into the test. if they aren't ready for you, go for another drive. DO NOT turn it off or let it cool. you want that cat very hot.

good luck
scott
 
emissions

In doing my round of TLC tonight (and changing the plugs). I found that I have one bad plug wire! The wires have the resistor built in (being that I have only ever had this euro model I'm not sure if all are like that) so the wire cap has a metal fitting with a clamping mechanism that fits over the threaded tip of the spark plug. well, in my wire #6 that entire piece is missing inside that cap (or boot). I'm not sure there any connection but she did not seem to run all that rough. I will replace the wires tomorrow, finish my maintenance and shoot for a re-test on wednesday. I will be going in HOT and we'll see what happens.

Dave L
 
it had to have been making some kind of contact or either your co or hc numbers would have been off the chart. fixing it will help for the long run. good luck, and let us know the good news.

scott
 
Emissions passed!

This morning, after changing the plugs, fixing the bad end on the #6 plug wire and some other minor maintenance items, I took the car for a 45 minute highway drive and straight into the smog test. She passed all the tests, and the failing NO test at 15 mph went down from about 3700 ppm (when she failed) to about 800 ppm. Passed all tests with flying colors. Now that is a testament to what a truly hot cat can do!

One more 26 year old car is back on the road!

Dave L
(Now I can go back to working on my e9)
 
You must log in or register to reply here.
Back
Top