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Failed Smog Test

1983 Buick Electra Park Avenue 5.0 307 High NO

My Buick Electra passed everything on the smog test except for the NOX. Its extremely high in 3000's. What are some ways I can reduce them besides an engine flush. I have replaced the thermostat all sensors and senders except throttle position sensor and I have already had it tested.


We recommend checking your Buick Electra's fuel control system first to make sure your engine is not running "lean". A lean fuel condition means enough fuel is not being delivered to the combustion chambers, causing the engine to run hot. NO is created when engine combustion temperatures rise above 2500f.

If fuel control is optimal (as close to 14.7:1 as possible) check engine compression. If compression is high (check your vehicle's repair manual for proper compression requirements - they should be on average around 110 PSI) you'll need to decarbonize the engine to lower compression and get your Buick's engine running cooler.

You should also make sure your Buick Electra's EGR system is functioning correctly. The EGR system is also responsible for lowering NOx emissions.

For more high NO faults click here.

posted by SmogTips Support

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