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740 Emission Test Failure

posted by  dan52 on  Sun Nov 7 19:51 CST 2004
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High NOx comes from excessive combustion temperature and or too much air in the fuel mix. Look for any place excess air can be entering the intake. Look at all intake hoses for holes or leaks. The corrugated hose is known for failure and hard to see unless you remove it from the car. Check vacuum hoses for condition and leaks. The seals around the fuel injectors are suspect as well as the intake manifold gasket. These can be checked by spraying with carb cleaner while engine is running. If idle improves, you have found a leak.

Timing is adjusted by rotating the distributor at the rear of the engine.

O2 sensor is located in the exhaust pipe before the catalytic converter. There are good instructions for testing posted here. Check the FAQ for the technique for setting base idle and CO.

Good luck,
Dan






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