'92 Regal failed CA emissions

1992
Buick
Regal
3.8L v6
Automatic
160K miles


Hi, on December 1, my car failed the CA emissions test with high HC and CO. It passed at 15mph, but failed at 25mph with HC measurement of 133 (max is 85) and CO at 3.58, which is at gross polluter level (max is .59). I was surprised because, even though my car is old, it has always passed with no problem in the past. The visual inspection turned up a leaking hose to the canister purge valve. I assume this could be the reason for the high HC readings, but would it also be the cause of the high CO reading?

Then this last Friday, the 15th, the Service Engine Soon light came on for a minute and then went off. I noticed that it would come on when I would accelerate to enter the freeway, pass another car, etc., and then turn off when I would brake quickly. Then I noticed when it was idling it sounded like the engine was surging like someone was pressing on the gas pedal again and again. These things don't seem to have any effect on the way the car runs - it still runs great.

If I replace the leaking hose, is it likely that my car will pass the emissions test? I don't want to take it in for unnecessary repairs if it's just the hose, but I also don't want to just replace the hose and then have it fail again. It has to pass emissions before I can renew my registration. Any advice? Thanks for any help

Welcome to AF.

I doubt the evaporative emissions system is the cause for high HC and CO readings. It is important to make sure the engine is in good tune and the EGR components are operating properly.

Now based on my experiences both high HC and CO levels is due to a bad catalytic convertor. Also, a bad CAT may cause the engine to surge as one of the symptoms.

1992
Buick
Regal
3.8L v6
Automatic
160K miles


Hi, on December 1, my car failed the CA emissions test with high HC and CO. It passed at 15mph, but failed at 25mph with HC measurement of 133 (max is 85) and CO at 3.58, which is at gross polluter level (max is .59). I was surprised because, even though my car is old, it has always passed with no problem in the past. The visual inspection turned up a leaking hose to the canister purge valve. I assume this could be the reason for the high HC readings, but would it also be the cause of the high CO reading?

Then this last Friday, the 15th, the Service Engine Soon light came on for a minute and then went off. I noticed that it would come on when I would accelerate to enter the freeway, pass another car, etc., and then turn off when I would brake quickly. Then I noticed when it was idling it sounded like the engine was surging like someone was pressing on the gas pedal again and again. These things don't seem to have any effect on the way the car runs - it still runs great.

If I replace the leaking hose, is it likely that my car will pass the emissions test? I don't want to take it in for unnecessary repairs if it's just the hose, but I also don't want to just replace the hose and then have it fail again. It has to pass emissions before I can renew my registration. Any advice? Thanks for any help
To add to Bob's info, the high hc's are usually caused by unburned fuel in the exhaust, I would look at the check eng. lite issue first, then that might point you to something, the surging is not normal and may be connected here. Scan it for present or history codes and post back. Watch for fuel contaminated oil also, this can be drawn in thru the pcv.

Hi, thanks for your replies. I got the diagnostic trouble codes. There are two of them. The first one is 13 (Open Oxygen Sensor Circuit) and the second one is 66 (Low A/C Refrigerant Charge). I'm assuming the two problems are unrelated...

I knew that something was wrong with the A/C. It stopped working during a trip I took at the end of October, but since I wasn't going to be using it again for several months, I put off having it checked. Does this new info give us any more clues as to what I need to do to get the car to pass emissions? Thanks again

Replace the o2 sensor or check the wire to it, , change the oil, make sure the vapor cannister is not loaded with fuel, clean air filter and no misfires?, I believe if all this is done and checked, you will pass. Remember the engine/cat must be good and warmed up to pass also.

Here's an update in the continuing saga: Rather than trying to do the repairs myself, I decided to make an appointment at a Gold Shield station. The Gold Shield stations are licensed to do the repairs and retesting of cars that failed emissions at a test only station, and they can certify gross polluters, so I figured that was my best bet. But now I'm not so sure... I don't really understand what they're doing, and it all seems very strange.

I dropped my car off at 9:00AM today, and they were supposed to perform diagnostic tests and then call me and let me know what they had found, in about an hour and a half, they said. Finally at noon they called me and said that they had started doing the tests but couldn't finish because it was "too rich". He said my car's computer wasn't working properly and so it wasn't storing any diagnostic codes. (very odd, because I had retrieved 2 codes from it just a few days before, and I didn't reset it). He said something about the voltage not changing like it should. He thought it needed to have the 02 sensor replaced, and once that was done, maybe then he could check the catalytic converter. But not today - he wanted me to pick up my car and come back next week, or next year, so they can finish the diagnostic test then and find out what needs to be done.

Here's what he wrote on the invoice: "Perform diagnostic tests and advise CO & HC high. 02 sensor bad - fixed at 195MV rises to 330MV with propane. After 02 sensor is replaced, diagnosis can continue." He also told me they ran the emissions test again and got much higher readings than when it failed. HC reading was 423, and CO was 10.1.

The original estimate for just the diagnostic tests and advice was $145. Now, they didn't really complete either of those things, and yet they still charged me $97. And sent me away half done, with no more answers than I had before the appointment!

Does this seem right? Can someone help make some sense of this for me? Thank you

I think they just confirmed what MAX said in post #5, that the 02 sensor is bad! Also, when an engine operates “rich” for an extended period of time, it can kill the converter. When the 02 sensor is functioning properly, the ECM will control the fuel curve using the feedback from the 02 sensor. When the 02 sensor drops to around 300mv, the ECM commands the fuel system to “go rich”. When the 02 output reaches 600mv, the ECM commands the fuel system to “go lean”. If you observed this function on a scanner, you should see a rapid flash, back & forth, between rich and lean.

Basically, the oxygen sensor measures the amount of oxygen in the exhaust system to determine if the engine needs more or less fuel. A regular oxygen sensor, commonly referred to as a” narrow band” o2 sensor (NB/O2) is only accurate at stoich (14.7) air fuel ratio (AFR)) and that is where an engine will produce the least emissions. A NB/O2 is only good at telling you if you are rich or lean, but never how rich or how lean you actually are.

Since 14.7 AFR is where it is most accurate and it is required to operate in such a narrow range, it is almost impossible to hold it there. When the ECM is using the O2 sensor to correct the fuel tables it measures how long it is lean and how long it is rich, if they are equal then the AFR is at 14.7, right where it should be. O2 "counts" is how many jumps back and forth it makes.:popcorn:

Thank you for your reply. It doesn't seem quite as strange to me now that you've explained it to me so well. I agree they just confirmed what MAX said in post #5. I guess I just expected them to at least try to fix it. It was like the guy really had no idea what to do. He was even vague about when I could bring it back in. Definitely didn't inspire much confidence. Now, you guys here really seem to know what you're talking about. You can even explain it to someone like me that knows next to nothing about cars. Thanks so much for the help and advice.

There is a high probability that after the 02 sensor is replaced you may still fail the test. As mentioned when you run rich for extended periods of time the CAT convertor internal temperature rises to unsatisfactory levels and may cause melt down. Also, old or high mileage CATs do not have adequate oyxgen storage capabilities. The readings you are currently getting sounds like what you would get with a gutted CAT or straight pipe bypass but definitely worse than the first readings.

Under California law how many days do you get to pass emissions after a failure. For example in Texas they only give you 15 days. You can do the work DIY or at a shop/dealer. In your case it looks like you are getting snowed by that certified "Gold Shield" station and as a result spending more money than necessary. Why don't you replace the 02 sensor yourself since it has been confirmed bad. The AC Delco part number is AFS20 and it is easy to replace. All you will need is a universal 02 sensor 7/8 "socket which has the cutout for the 02 sensor wiring harness. Located on the exhaust manifold/crossover. Available at places like Autozone, Advance, Checker/Kragen/Schucks.

The part I don't understand is why it passed the 15 mph test and failed only at the higher 25 mph test. You'd figure with solely a bad 02 sensor it would fail both tests. Do they actually run the car on a test fixture like on a dynometer for the 15 and 25 mph tests with the wheels spinning? All they do here is run two static tests at low rpms and high. The standard is HC-220, CO-1.20 on both tests in Texas which is obviously less stringent than California.

On my wife's '99 Regal LS here are the results on 12/14/06:

RPM: 2540 - HC=9, CO=0.20
RPM: 706 - HC=21, CO=0.02

Nice to know I would pass California emissions with flying colors. :grinyes:

BTW - The convertor was replaced about 18 months ago and I recall the HC and CO readings were higher but it has never failed emissions.


Hi, on December 1, my car failed the CA emissions test with high HC and CO. It passed at 15mph, but failed at 25mph with HC measurement of 133 (max is 85) and CO at 3.58, which is at gross polluter level (max is .59).

To add to Bob's usual comprehensive info, make sure the fuel pressure is within range and the oil is not contaminated. I've heard stories about these specialty shops gauging as a result of the desperation and paranoia about the emissions test. Here in NY we are doing an obd11 plug in test only, in the NYC area they do a tailpipe/dyno test on pre obd11 cars. We have an emissions waiver here, if 450$ work is done and the car improves from the failed area on the initial test, but still fails, you get a one year hardship waiver. You can do a cat efficiency test on your own to get an idea what's what after checking all the suggested issues and replacing the o'2 sensor. If you can get a non contact infra-red thermometer, get the car good and warmed up by driving it then check the cat inlet vs outlet temp, the outlet should be at least 100 degrees more than inlet temp, if the cat is working.

Here in NY we are doing an obd11 plug in test only, in the NYC area they do a tailpipe/dyno test on pre obd11 cars.

Shep, that is interesting you raised that about odb-ii plug-in testing. Effective 1/1/07 17 counties in Texas to include El Paso are going to that for '96 and up odb-ii cars. No more sniffer in the exhaust tailpipe test except for pre odb-ii cars. That Actron CP9145 scanner I bought a few years ago should really come in handy now to check IM readiness for the odb-ii emissions test. One down, two to go under the new standards. Better safe than sorry. :thumbsup:

Bob, it seems the tailpipe test on obd11 going by the wayside all across the country. The 9145 is a great quick check for IM readiness, also cuts down on drive cycle worries and time after clearing a code, while driving you can see the monitors come online, Here in NY you are allowed 2 monitors not ready and it will still pass.

Hi guys!

I'm not sure if we have a time limit for when we have to pass after a failed test or not. I checked around and couldn't find any info on that. But I can't get my tags until it passes the test, and of course I put it off until the last minute so my registration is already expired.

I have no idea why it would pass at 15mph (1711 rpm) but not at 25mph (1654 rpm). Your guess is better than mine! When the guy told me that the computer wasn't working the way it should, I told him maybe it had a virus :iceslolan

The test they do here is called BAR-97 ASM (dynometer). I believe ASM stands for Acceleration Simulation Mode, or something like that. They put your car on a machine that's like a treadmill for cars and it makes the wheels spin while they perform the various tests. They have some sort of probe that's hooked up to a computer that they stick in the tailpipe, and all the readings are recorded and immediately sent in electronically. They also do a visual test and a functional test so they can identify crankcase and cold start emissions which aren't measured during the ASM test. My car failed the visual test, too, because of the leaking hose. But of course, you probably already know all of this - I'm sorry!

I don't think California has a spending limit on emissions related repairs, but we do have a program that will help people who qualify with the cost of repairs that go over $500. And if you decide not to have your car repaired, they will give you $1000 to retire it.

I'm probably going to change the 02 sensor myself (or maybe I should say, I'm probably going to have my husband help me change the 02 sensor). Which is what I had originally planned after talking to you guys here, but for some dumb reason I changed my mind and decided to let the so-called pros handle it. You know, expired registration... I don't want to get a ticket... blah, blah, blah. But the whole situation with the smog place gave me a bad feeling - it just seemed off.

Here's a funny coincidence - a friend came over yesterday, and for some reason gave me a non contact infra-red thermometer. Can you believe it? It must be some sort of a sign!

I'll keep you guys posted on what happens. And I'll most likely have more questions before it's all over, if that's ok. I really appreciate all the help and good advice I've been given by everyone here. Thanks so much - you guys are pretty cool!


I need to make a correction - the CO reading on the new test was 7.40 and not 10.1. The CO2 reading was 10.1. Still higher, but just not as high as I had originally told you.