: Failing Emissions Test

DopeStar 156
07-08-11, 10:58 AM
Hey everyone. I need some emissions help here....

So, for the better part of a year my 89 Fleetwood Brougham has been failing state emissions for mainly hydrocarbons (HC ppm.) So far I've done the following work to the car.....

- New O2 sensor
- Repaired vac leaks
- Smog pump wasn't connected right, reconnected everything
- Repaired bad ground connection to ECM
- New exhaust system with Magnaflow performance catalytic converter.
- Retuned carburetor to factory settings
- Restored correct timing (was retarded about 4 degrees)

Here are my thoughts on what's wrong at this point.

- The inspection station shut my car off for a minute or two, restarted it and after about 30 seconds started doing the emissions test. I feel like the car may have been in open loop when they did the test because the HC ppm went up from 445 to 733.

- My second thought is I heard certain O2 sensors on these cars don't heat up enough and cause malfunction. I put a new Bosch O2 in the car last year, maybe it's no good?

I'm close to just taking the car to an emissions place at this point since I need it ready for a road trip to the CLC Grand National in early August. Can anyone provide some insight here? I'm running low on time and have other work to do before I can go!

07-08-11, 01:03 PM
Try AC Delco O2. If the car is hot, it won't go to open loop when they restart it. Make sure the car is HOT when you get it to the test location. I have no experience, but others have reported that aftermarket "performance" cats don't work as well as stock.

07-08-11, 02:24 PM
^This. Going all stock on the emissions stuff is the best way to help the car get to it's emissions target. And always have the smog tests done when the car is hot. Drive it at least 50 miles before going to the station.

07-08-11, 09:13 PM
Replacing the plugs, ignition coil, and wires should improve hydrocarbon emissions, somewhat, if you haven't done a tune up in a while. You might also want to do a compression test, because low compression in one or more cylinders can cause unburnt fuel to enter the exhaust. You should also verify that the smog pump is actually working, because if the converter isn't getting enough air, it can't get hot enough to burn the hydrocarbons.

07-09-11, 04:18 AM
Run the gas tank to almost empty, down to a gallon or two. Go to the test station, put a whole bunch of Heet fuel additive in the tank and remove the air filter. You'll pass instantly. Then put the filter back in and go fill it up right away, driving very lightly. You'll be running lean. I tried this on a car that consistently could not pass, and it worked like a charm. I don't know how much Heet I put in, could have been three bottles, could have been five or six.

07-09-11, 05:29 AM
When was the last time you changed the oil and filter? With time the oil could get contaminated with fuel, which in turn might cause high HC readings.

07-09-11, 01:40 PM
I just got mine tested, and the first reading was 152 ppm hydrocarbons. The limit here is 99 ppm. I ended up doing a tune up. ( Plugs, wires, cap, rotor, and a fuel filter.) I also did a oil change. After i did that the car wouldn't start right. it sounded like it was misfiring for the first 5 seconds it ran. then It would smooth out. I found out that the vacuum line running from the map sensor to the throttle body was very brittle. so i replaced that an it worked great. I went back to the testing station and I passed. Not by much though, It read a 98.5. The first time I had to get a Echeck when I got the car years ago, it failed horribly. I can't remember what the numbers were. I ended up doing a tune up and a new Catalytic converter with the rest of the exhaust. Also I know here if you spend $300 on emission related things to fix your car within the last 60 days, they will pass you automatically. I hope this helps