Smog emissions test

Hi All,

Just had a smog test for our 1990 E30. It passed... but barely.

@ 15mph (1888 rpm)
%CO2 = 14.5
%O2 = .2
HC = 43/108(max)
CO = .17/.71(max)
NO = 681/767(max)

@ 25mph (1948 rpm)
%CO2 = 14.6
%O2 = .1
HC = 16/83(max)
CO = .12/.40(max)
NO = 706/706(max)... heh...

So I looked up high NO emissions...

1. Lean Fuel Mixture
2. Defective EGR System
3. Defective Catalytic Converter
4. High Engine Mileage - carbon build-up
5. Engine Overheating

High NO (nitrous-oxide)

I guess now that it passed smog, I can just forget about it for 2 years if the car survives until then. But it just bugs me and I don't want it hanging over my head 2 yrs from now.
This is the car where we replaced the head late last year after my son forced the car home with a blown water hose.

I really don't know where I could start and I don't exactly want to dump a lot on money on this car at this time...

#1. Says O2 sensor could be bad.. I've never replaced it.. how do I know if it's bad?

#2. Does this car have a EGR system?

#3.. Bad CAT... Suppose that's possible.

#4. High mileage. YES.. but odometer has bad gears.. shows 192k but its got to be at least 230k if not more... I haven't driven the car in 7 years so I don't really know the miles. But it says carbon buildup.. well the head was replaced recently and it was pretty clean. Pistons had some carbon, but I don't know that it was that bad. Buildup elsewhere?

#5. Overheating? Gauge shows OK temps unless it's bad... IDK

Anyone have any ideas? Kinda tough to diagnose this... and going back to a smog station after every "fix" is not a good option either.. I suppose replacing the O2 sensor would be a cheap fix and good for the car in general.. No?

Quote
sdp
Hi All,

Just had a smog test for our 1990 E30. It passed... but barely.

@ 15mph (1888 rpm)
%CO2 = 14.5
%O2 = .2
HC = 43/108(max)
CO = .17/.71(max)
NO = 681/767(max)

@ 25mph (1948 rpm)
%CO2 = 14.6
%O2 = .1
HC = 16/83(max)
CO = .12/.40(max)
NO = 706/706(max)... heh...

So I looked up high NO emissions...

1. Lean Fuel Mixture
2. Defective EGR System
3. Defective Catalytic Converter
4. High Engine Mileage - carbon build-up
5. Engine Overheating

High NO (nitrous-oxide)

I guess now that it passed smog, I can just forget about it for 2 years if the car survives until then. But it just bugs me and I don't want it hanging over my head 2 yrs from now.
This is the car where we replaced the head late last year after my son forced the car home with a blown water hose.

I really don't know where I could start and I don't exactly want to dump a lot on money on this car at this time...

#1. Says O2 sensor could be bad.. I've never replaced it.. how do I know if it's bad?

#2. Does this car have a EGR system?

#3.. Bad CAT... Suppose that's possible.

#4. High mileage. YES.. but odometer has bad gears.. shows 192k but its got to be at least 230k if not more... I haven't driven the car in 7 years so I don't really know the miles. But it says carbon buildup.. well the head was replaced recently and it was pretty clean. Pistons had some carbon, but I don't know that it was that bad. Buildup elsewhere?

#5. Overheating? Gauge shows OK temps unless it's bad... IDK

Anyone have any ideas? Kinda tough to diagnose this... and going back to a smog station after every "fix" is not a good option either.. I suppose replacing the O2 sensor would be a cheap fix and good for the car in general.. No?

Hey, Any idea how old the cat is?, and how long you have owned the car. Or, and, if you have the history so we can know certain things needed to make suggestions; often cats will come apart and lodge in the rear section if they've been on there too long. This is usually easy to figure out. Is your motor a 4 or a 6 cylinder???

Hows your gas mileage?

These cars are pretty simple; if you replace the cat and 02 sensor (if you don't have any serious other problems) the cars usually respond well on the smog machine tester thingy, speaking of which, what state are you in. Here in new york we have tests every year, on a dyno and they're serious!

Cheers, Rick



Edited 1 time(s). Last edit at 04/15/2011 03:58PM by rkj.

Hi Rick,

I'm the original owner 1990, 6 cylinder 325is... The CAT is original, O2 sensor is original.. 200k++++ miles

I haven't driven the car in 7 years so it's hard to even estimate the mileage especially since the odometer doesn't really work..
This car has the extended onboard computer with the extra buttons.. is the gas milage on that independedent of the "odometer"?
I guess I can have my son reset the computer and see if it registers mileage.. The backlight in it is burned out, but you can still see the numbers with a flashlight or in the sunlight.

If the CAT is dead, if I were to shake it, would I hear noise.. Does it physically fall apart inside?

I'm in California.. it's every 2 years here on a dyno.

Thanks,
Peter



Edited 3 time(s). Last edit at 04/15/2011 05:19PM by sdp.

I would wager that if you had the injectors cleaned and changed the o2 sensor you would be good to go.

Bob in Lake Havasu

Quote
sdp
Hi Rick,

I'm the original owner 1990, 6 cylinder 325is... The CAT is original, O2 sensor is original.. 200k++++ miles

I haven't driven the car in 7 years so it's hard to even estimate the mileage especially since the odometer doesn't really work..
This car has the extended onboard computer with the extra buttons.. is the gas milage on that independedent of the "odometer"?
I guess I can have my son reset the computer and see if it registers mileage.. The backlight in it is burned out, but you can still see the numbers with a flashlight or in the sunlight.

If the CAT is dead, if I were to shake it, would I hear noise.. Does it physically fall apart inside?

I'm in California.. it's every 2 years here on a dyno.

Thanks,
Peter

Hi Peter

Yes, often when cats get to a certain age they can come apart internally and the pieces go in to the rear section so the whole shootin match gets fouled... A useful life of a cat is about 100k, anything more is a gift, although my eta had almost 200k before it crapped out completely on the way home from south Carolina one year!

Give your car a break ; a complete exhaust and an 02 sensor, it will love you back instantly. Running motors with those clogged up exhaust systems will do damage.

Rick

Philosophically, I line up with Bob. My 87 325 just passed emissions here in CA with 231K miles, original cat, 02 sensor about 60,000 miles. My CO and HC aren't that much different than yours and my NO is around 500. Depending on your goal here, you have two years before you need to test again. If the car is working good, drive it and enjoy it. Before the next test, run a can of Sea Foam through one tank of gas. Then run Chevron 91 octane for a tank (Hot Rod Magazine did some kind of test and said it made a difference-I'm kind of skeptical but I do it and my 325 has never failed smog in CA so I keep doing it). I do think if you have never changed the O2 sensor, I would change it before your next test. You probably don't have carbon build up or EGR issues....you would have other problems if you did.

Just my two cents, drive and enjoy.
Doug S

Thanks all...

I think an O2 sensor change would be a easy fix and would probably help the gas mileage, no?
BavAuto and PelicanParts are in the $80-90 although I see them for sale on Amazon & EBay for about ~$55.
Anyone have any experience with parts through Amazon/Ebay?
EBay O2 Sensor
Amazon O2 Sensor

These cars would have real problems if the EGR plugged up

I am going to have to get under the hood and find that pesky EGR valve...

Bob in Lake Havasu