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925benjie

Smogged But Failed

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Had to get the '92 ES 300 to smog test station yesterday and failed the test. Had no problems during the prior years passing but not this time. It passed the visual inspection and functional check except the emission test. The HC (ppm) and the NO (ppm) was above max. but below gp(gross polluter). However, the CO (%) was way higher than the gross polluter allowable limit. I warmed up the car for about 30 mins. prior to taking it to the station. Any suggestioms or DIY info i can do before taking it back for a retest would be much appreciated.

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Ok, how many miles ago was that? I know in some spots of the country, people put a lot of miles on their cars. Things to look for (besides the obvious tuneup things ) are the PCV valve, also clean the airflow meter. These cars use a mechanical vane flowmeter. Buildup around the vane will cause all sorts of mixture problems. Also how many total miles do you have on the car? It could very well be time to change the O2 sensors.

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CO, Carbon Monoxide “HIGH”

Air /fuel mixture too rich

Air entering exhaust before 02 sensor

Air filter restricted

Air induction system restricted ; after accident

Air injection system injecting air upstream of 02 sensor

Crankcase breather filter plugged

ECT sensor voltage too high for actual engine temperature

Engine oil fuel saturated SHOULD BE 500 PPM OR LESS

Evaporative canister fuel saturated

Exhaust system restricted

Fuel injector leaking

Fuel pressure regulator manifold vacuum hose plugged

Fuel pressure too high

MAF sensor signal too high for amount of air actually entering system

MAP sensor vacuum hose leaking

MAP sensor voltage signal to PCM too high for actual engine load

M/C solenoid disconnected on feedback carburetor

02 sensor lean biased

02 sensor not functioning

02 sensor voltage too low

PCV valve plugged

PCV vent in air cleaner plugged

power valve leaking

TPS sensor voltage signal to PCM too high for actual engine load.

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Ok, how many miles ago was that? I know in some spots of the country, people put a lot of miles on their cars. Things to look for (besides the obvious tuneup things ) are the PCV valve, also clean the airflow meter. These cars use a mechanical vane flowmeter. Buildup around the vane will cause all sorts of mixture problems. Also how many total miles do you have on the car? It could very well be time to change the O2 sensors.

Did oil and filter change, spark plugs and belt with about 169K miles. It now has 179K. Anyway, I will follow your suggestions and maybe take it further all the way to the intake manifold if that would make a difference. I got time this coming weekend. Thanks "George'.

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If the O2 sensors are original, it would be a good time to replace them. Also check the fuel pressure regulator. If the diaphragm inside the regulator starts to tear, it will allow un-metered fuel into the engine. Also check all your vac hoses, especially the ones to the regulator. After that I would check the coolant temp sensor. Keep in mind that the ECM uses it's own coolant temp sensor, so do not assume that a working gauge in the dash means that the coolant temp sensor is good. A couple cans of fuel injection cleaner would not hurt either. Of course there are other things, but list will get you started.

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Just posting an update. Followed all recommendations suggested by GH and took it further. Removed from air intake,throttle body,valve cover to intake manifold. Replaced all the gaskets, some hoses that i broke, spark plugs,oxygen sensors,pcv and air filter. Did a lot of cleaning due to the amount of dirt built up on most of the parts involved particularly the throttle body,egr valve,idle control valve and the intake manifold. Put them all back together with no excess parts which was good. Anyway, what a difference. The car runs so much smoother and power. Hopefully, it would pass the retest this weekend. I will cross my finger until then.

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Finally went to the smog station for the retest. I waited another week to burn most of the fuel in the tank since i added a can of fuel system formula and also did an oil and filter change. Went to the gas station and put three-quarter tank full of premium unleaded and drove it for at least 30 minutes until the temp. gauge is at the normal operating temp. and went straight to the smog station. The smog tech took it in right away and within 15 mins. came back with a passing grade. He even asked me what i did with the car because the emission test showed so much improvement from the previous one. I told him i owe it the the guys on the club who gave me some pointers. Now, on to the next project, replacing the cv boots. Thanks.

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I'm to hear that we could help, I'm sure that you saved a lot doing it yourself.

You bet! Many thanks for the suggestions,G.J..

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