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1988 Blazer 2.8L V6 s-10 4x4. 220 TBI intake. Everything is stock.

This vehicle does not pass emissions. The OBD1 indicates a lean flag, The pvc valve is new. The fuel canister does not appear to have restricitons. Ignition timing is dead on. Gas cap is good. New fuel injectors were installed. What is the specification air pressure on the output side of the smog pump?
Answer:

We have to recommend checking the Oxygen Sensor on your Chevy Blazer. If in fact the trouble code is accurate, you'll have to find out why the engine is producing low carbon monoxide (CO) and triggering a lean flag or lean trouble code. You'll need to do a fuel injection "feedback" test. You'll need to check and make sure the oxygen sensor is working properly and the engine control computer (ECC) is sending the right amount of fuel to the combustion chambers. The "feedback test" is conducted using propane. Propane is added to the air intake system while measuring voltage output from the oxygen sensor as the engine is running at idle; you should see an increase in voltage up to .90 volts, and the injector pulse width should immediately decrease. If this does not happen, we know we have a feedback problem. From there you'll need to find out which part of the feedback system is at fault; the oxygen sensor, the fuel injector, the engine control computer, or the wiring between these components. At the end of the feedback test it will be know whether the low CO fault is electronic or mechanical, and the technician can further diagnose the fault. posted by SmogTips Support

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