High Hydrocarbons Cause 1989 Oldsmobile to Flunk Emissions Test

The car in question is a 1989 Oldsmobile Custom Cruiser, a full-size station wagon, VIN 1G3BP1Y6KRxxxxxx. It has the "Y" code 307 cid (5L) V8, carburetor, air conditioning, cruise control, and leveling suspension in the back.The engine management system is the GM CCC system. The car has only 27,100 miles. Yes, that is low. It was my parents' car, and it was given to me in the year 2000. It has to pass the northern Virginia emissions test every two years before I can renew the registration. Test is conducted under standards set by the Virginia Department of Environmental Quality; their website is

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. I have the usual hand tools available to me. I also have a timing light, compression gauge, code scanner, vacuum gauge, dwell tachometer, several voltmeter/ohmmeters, and some oscilloscopes. I have a few decades of experience working on cars on an amateur basis. I have rebuilt the engine and the automatic transmission in my 1976 Cutlass. I feel comfortable working on cars, but I have come to dread the emission test, for the reason that I cannot see parts per million or percents of pollutants in the exhaust.

I had trouble getting this car through this inspection two years ago, but nothing like what I am encountering now. Then, the problem was high NOx. I installed a new EGR valve, and a new O2 sensor for good measure. This year, I took it in for inspection on August 16. The local gas station has two inspectors, Shakur and Leon. The equipment there is a treadmill attached to a workstation. The name of the test is the "ASM2 tailpipe emissions inspection." The process is automated, so I figure that it doesn't matter which inspector is doing the procedure. If you flunk the first test, you get one free reinspection. All the others cost $28 each and every time.

For the first test inspector, I had Shakur. The car flunked. Here are the results:

August 16, 12:46 p.m. Idle 800 rpm according to the test machine's display. HC, ppm: 15 mph: limit 55; actual 116 (fail) HC, ppm, 25 mph: limit 100; actual 138 (fail)

CO, %, 15 mph: limit 0.22; actual 0.06 (pass) CO, %, 25 mph: limit 0.32; actual 0.08 (pass)

NO, ppm, 15 mph; limit 720; actual 256 (pass) NO, ppm, 25 mph; limit 700; actual 309 (pass) Overall test results: fail.

The limit numbers change from year to year, by the way, so if you happen to have a form from a few years back, you might see different limit numbers on your form than those that apply in 2006.

When I got back home, I saw that the gas cap, which had been removed for pressure testing, was missing. The car had been tested with no cap in place. I went back, thinking that with the cap in place, surely the car would pass. Shakur had gone for the day. Leon ran the test, and the car flunked again.

August 16, 4:33 p.m. Idle 800 rpm according to the test machine's display. HC, ppm: 15 mph: limit 55; actual 82 (fail) HC, ppm, 25 mph: limit 100; actual 83 (pass)

CO, %, 15 mph: limit 0.22; actual 0.04 (pass) CO, %, 25 mph: limit 0.32; actual 0.00 (pass)

NO, ppm, 15 mph; limit 720; actual 232 (pass) NO, ppm, 25 mph; limit 700; actual 279 (pass) Overall test results: fail.

"That was your free reinspection," I was told. I didn't think that was right, as it wasn't my fault that the original test had been run incorrectly. The next day, Shakur agreed with that and said he would give me another free test. He said that with a set of new plugs and wires, the car ought to pass the test. He also said to make sure it was good and warm when I brought it in.

So I got plugs and wires. As it develops, one of my wires was bad; the spark plug wire to the #3 cylinder had infinite resistance. Taking a look at the cap and rotor, I found the rotor also had infinite resistance. Obviously, the higher voltage present when the rotor was in use could bridge the open spot in the rotor. The cap had some corrosion, so I threw in the new cap and rotor as well. I put on a new air filter too. I checked the timing; it was right, something like 20 degrees BTDC, IIRC. I turned the idle down to 550 rpm, at which speed the engine was prone to stall. All this was done according to the procedures specified on the label on the radiator shroud. I went back for my third test, this time again conducted by Shakur. I drove it in from the adjacent county, so it was nice and warm. Results:

August 23, 11:06 a.m. Idle 570 rpm according to the test machine's display. HC, ppm: 15 mph: limit 55; actual 145 (fail) HC, ppm, 25 mph: limit 100; actual 232 (fail)

CO, %, 15 mph: limit 0.22; actual 0.06 (pass) CO, %, 25 mph: limit 0.32; actual 0.23 (pass)

NO, ppm, 15 mph; limit 720; actual 269 (pass) NO, ppm, 25 mph; limit 700; actual 398 (pass) Overall test results: fail.

Right. It was worse than before I put on the new parts, a lot worse. Talk about a sinking feeling. I couldn't work on the car for a while, but when I got back to it, I took a close look at the hoses. I found three that were bad, including one with a split about an inch long. One of the leaking hoses provided vacuum for the cruise control. I replaced all the bad hoses and dug out my vacuum gauge. I hadn't used one in so long that I had forgotten how to use it. None of the manuals I could find had information on its use, but a website told me what I should be looking for.

"How to Use and Interpret a Vacuum Gauge"

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With the bad hoses replaced, I could get 23 inches vacuum as soon as the car started, with the engine running at a substantial rpm. The needle was steady. Satisfied there were no vacuum leaks, I took the car in for its fourth test. Shakur ran the test. As the car was on the treadmill, I watched the test machine's display. The screen flashed red several times before the machine announced that the test was being aborted due to something called "low flow." That will be $28, said Shakur.

August 28, 10:33 a.m. I didn't notice the idle on the test machine's display. HC, ppm: 15 mph: limit 55; actual N/A (N/A) HC, ppm, 25 mph: limit 100; actual N/A (N/A)

CO, %, 15 mph: limit 0.22; actual N/A (N/A) CO, %, 25 mph: limit 0.32; actual N/A (N/A)

NO, ppm, 15 mph; limit 720; actual N/A (N/A) NO, ppm, 25 mph; limit 700; actual N/A (N/A) Overall test results: failed/invalid.

Well, what in the world? Shakur said there must be a leak somewhere in my exhaust. Back home, I rolled the car up onto a set of ramps and inspected the exhaust. It had been replaced behind the catalytic converter in about 1999, so it was good and rusted. The metal donut that goes between the right hand exhaust manifold and the exhaust that pipe that leads to the catalyic converter had deteriorated and called for replacement, but there were no gross leaks. The system as basically tight and leak free.

I got on my bicycle and made the ten minute trip to the Cadillac dealer. Since some Cadillacs used the 307 motor, I figured they might have some insight. I couldn't talk to the inspectors until the evening, and when I went back, I showed them the test results. They told me right away that the problem with low flow was not with my car, but with the test machine. An exhaust leak would not cause that condition. I ought to get another test at no charge.

The next morning, I called the Virginia DEQ and expressed my frustration with what was going on. I pointed out that I had no problem with the person running the test; rather, I couldn't understand what had happened. The person at the DEQ pulled up my test results at his own terminal and handed it to the DEQ inspector. The inspector said he couldn't understand the results either, so he went over to the gas station where the test was being conducted to look at the machine. I didn't have the time to go down to the gas station to talk to him there, but he called after he got back to the office and said that Shakur wanted me to bring the car back in for another free test.

I got back to work on the car. When the weather permitted, I installed the new metal donut. During that procedure, I broke the air tube that connects the air injection check valve to the catalytic converter. That was a special order. Eventually, I had all the parts in place. I got in the car to drive off the ramps, started it, and put my foot on the brake pedal. The pedal went all the way to the floor. The rusted brake line to the left front wheel was obvious. Recall that the car has only

27,100 miles, and you'll understand that the left front wheel could be so rusted in place that it took two days to remove it. I wanted to check all my brakes. I found the left rear wheel rusted in place too. The wheels on the right side were fine. OK, with a one-time extension on my car's license plates, I went back to the gas station, taking the long way to get the car warm. I checked the vacuum on the way; it was 21 inches and steady.

October 4, 11:17 a.m. Idle 538-540 rpm according to the test machine's display. HC, ppm: 15 mph: limit 55; actual 59 (fail) HC, ppm, 25 mph: limit 100; actual 79 (pass)

CO, %, 15 mph: limit 0.22; actual 0.01 (pass) CO, %, 25 mph: limit 0.32; actual 0.04 (pass)

NO, ppm, 15 mph; limit 720; actual 136 (pass) NO, ppm, 25 mph; limit 700; actual 188 (pass) Overall test results: fail.

Right. Failed again. At this point I had no idea what to do. I went back to the Cadillac technician. He suggested pouring into the carburetor a can of a product that GM sells called "Top Engine Cleaner." I've used it in this car before, back in 1998 or so. I had asked him in August if I should try that, but at the time, he had said it would be a waste of money. Clearly by now his mind had changed. He also said that after doing that I should "drive the car hard." Following the instructions on the can, I poured it in. I had non-automotive chores to take of later that day, so I have not gone for the brisk drive yet. It was at this point that I composed my post at sci.electronics.repair and sci.environment. I noticed an old post at rec.autos.tech in which the poster, discussing a similar situation, suggested looking at the air injection system. I haven't done anything along those lines yet.

If the car does not pass, it cannot be registered. A waiver is possible, but only after I have spent $680 on repairs. The work must be done by a certified technician at a certified repair facility. All the work I have done and the parts that I have installed up until now do not count. According to my latest tax statement, the car's value is $700. I would probably end up selling the car to someone who lived outside the area where the test is required. That person would be the big winner, as he would get a car that would serve him well for years and years. Inevitably, as the car drives absolutely flawlessly, he would put not 1500 miles per year on the car, but 1500 miles per month. The hydrocarbon emissions would still be high, but no one would care. I would lose a car, and the environment would be worse off.

You now know what I have done in an attempt to get my car through the emissions test. Please give me your ideas.

Thank you.

Reply to
Beloved Leader
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Reply to
Shep

It's funny you should mention that. Earlier this year, I was certain that I had a gas tank leak. Due to the cost of gasoline, I never filled the tank. Rather, I kept only enough gas in the tank to take care of any errands that may arise. When I parked the car after putting in a few gallons of gas, there would be a strong odor of gas around the back of the car. Also, there would be a drop of gasoline on the bottom outside of the tank. The ground beneath the tank would not be wet with gasoline, as the drop of gasoline evaporated in place. I thought the seam where the top half of the tank joins the bottom half of the tank had rusted through, and I was prepared to replace the tank, at no small expense.

For the emissions test, I removed the charcoal canister, cleaned its filter, and cleared out the loose leaves and dirt in the vicinity of the bottom of the canister. Later I found and replaced three hoses with holes or a split, eliminating my vacuum leak. To my surprise, once I did that, I eliminated my gas tank leak too.

I have know for some time that vacuum leaks manifest themselves in unusual ways, but I was surprised to discover that my gas tank leak was actually a vacuum leak. At least I dodged the bullet of having to spend $170 on a new gas tank.

Reply to
Beloved Leader

Wait a sec, it's possible to interpret that situation another way:

Before you had a slow gas tank leak, but only when the tank was under pressure. Most cars pressurize the fuel tank a little bit as part of their vapor recovery system.

After you messed with the canister, you may have introduced a small air leak. That would cause the gas tank pressure to drop to zero very quickly after turning off the engine. Without pressure, the rusty gas tank seam or whatever doesnt leak. So this "improvement" may actually be a step backwards. With low or no gas tank pressure, the vapors may not be getting scavenged by the charcoal canister, and/or the vapors may not be being purged during normal engine operation. I'd take a whiff of the canister-- if it smells strongly of gas, it's probably gas-soaked and needs replacement, or fix the problem in the scavenging system and run the engine for a few hours and that *might* clean out the canister. In many cases of a really soaked canister, replacement is the only viable option.

Reply to
Ancient_Hacker

Well, that _would_ be the story of my life.

I'll do that. Thanks for pointing out something I had not considered at all.

Reply to
Beloved Leader

(Later) I opened the hood, leaned in, and took in a big ol' snort. There is no smell of gasoline in the vicinity of the charcoal canister. Bonus observation: this canister, and the vacuum supply tank for the cruise control, are located in what would be the battery tray in a car with dual batteries. That would be the diesel engine Oldsmobile. I had never noticed that before.

Thanks again for the suggestion.

Reply to
Beloved Leader

Try removing one of the lines going to the canister and sniff the canister end.

Reply to
Ancient_Hacker

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