2006-06-12 15:27:23 · 3 answers · asked by gaensebl 1 in Cars & Transportation ➔ Maintenance & Repairs
fix the egr flow rate and or system
check basic timing
check that it's not running to hot or too lean of an air/fuel ratio
replace the lazy or defective upstream oxygen sensor
last but just as important, Replace the defective catalytic converter with a OBD II Calif. Appproved unit
2006-06-12 15:37:11 · answer #1 · answered by Magikmann 4 · 0⤊ 0⤋
1. Test your vehicle on a nice day only--avoid very cold or windy days. Cold weather requires that the engine be run longer for the coolant, oil, and catalytic converter to reach and maintain optimum operating temperature.
2. Make sure your battery is in good condition. A weak or low-voltage battery causes many fuel-injected engines to run rich (use too much fuel).
3. Change engine oil before having the vehicle tested. Dirty or contaminated oil increases exhaust emissions.
4. Use premium gasoline to help reduce nitrogen oxide (Nox) emissions.
5. Do not overfill the gas tank. After the nozzle clicks off, add no more than a dime’s worth of fuel. If the tank is overfilled, liquid gasoline can be drawn into the engine through the canister purge system.
6. Drive at least 20 miles before having the vehicle tested.
7. Arrive at the test center with only a quarter- to a half-tank of gasoline.
8. While waiting for the inspection, place the gear selector in “park” or “neutral,” and keep the engine running at fast idle (about 2500 rpm).
9. Before testing begins, turn the air conditioning/heating or defroster to the off position.
2006-06-12 15:41:05 · answer #2 · answered by Steve-o 3 · 0⤊ 0⤋
NOx emissions which are too high are caused by temperatures being too hot in the combustion chamber.
The typical emissions device that is used to reduce NOx emissions is the EGR valve, which would be the first thing I'd check. Make sure it's working properly and not clogged. If you can remove it and clean it that would be best.
Otherwise you're looking for ways to reduce temperature in your combustion chamber.
What type of car is it, what year and what's the mileage?
How far off are you from passing the NOx emissions?
2006-06-12 15:41:30 · answer #3 · answered by hsueh001 5 · 0⤊ 0⤋