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91 Camry Le.. Failed emissions NOx and very high % O2... Help

I just had my 91 Toyota Camry Le inspected for emissions. It passed everything but NOx. I had the following readings

High Speed Test Low Speed Test

Standard Current Standard Current

HC 123 26 128 127 CO (%) .69 .13 .71 .31 C02(%) 14.6 14.4 O2 (%) 19.7 20.4 NOx 878 1093 970 947

The part that I am especially puzzled about is the very high O2 readings. In my test of last year, I had readings in the .5% range. How in the world can I get a reading of 20% or more? In fact, isn't the atmospheric % of O2 in the range of 20%? Is it possible that I had a reading which reflects only that of atmospheric O2?

I would appreciate opinions on what is going on.

Thanks, Al

Reply to
Al Kondo
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Several things can cause high Nox.

Check your EGR valve function by applying vacuum to the EGR while the engine is idling. If the EGR is functioning properly, the engine will start to stall if you apply EGR at idle. If the engine starts to stall when applying vacuum, check the vacuum switching valves that control the EGR. This link

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explains some of the emissions control systems, including the EGR valve and controls. Also check ignition timing and advance.

This link has info for the rest of the car:

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Reply to
Ray O

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