Greetings All,

I am new to the forums and I am looking for information for my 89 S10 4.3L Blazer. I recently failed smog for high HC's and want to check some components prior to purchasing a new CAT. My CO was a little high and I have experienced in the past if I can get my CO's to lower the HC's will sometime follow suit.

HC's MAX AVG MEAS
15 121 55 127
25 75 41 121

CO MAX AVG MEAS
15 .49 .12 .36
25 .63 .14 .34

NO MAX AVG MEAS
15 704 176 234
25 606 149 170



I have done an oil change, new dist cap & rotor, new plugs & wires, new EGR valve, new O2 sensor. In the last two years I have replaced the Ignition Control Module, all vacum hoses, fuel pump & filter and MAP Sensor. I have also replaced the Air and cannister filters. All of this and I still failed smog.

I would like to find out the voltage values and how to test the Electronic Vacuum Regulator, MAP, and O2 sensor.

 

You will need an oscilliscope to be able to watch the O2 sensor.

The MAP sensor is just a straight up voltage output. Its output with the engine-off/key-on changes depending on your altitude.

And I think you are describing the EGR solenoid when you state "electronic vacuum regulator". The EGR solenoid sends vacuum to the EGR valve when commanded to by the ECU.

 

To bring down the HC emissions you can run the gastank down to less than 1/4 and dump in a gallon of alcohol (Methyl Hydrate). Alcohol is clean and hotter burning and gasoline is not. If your fuel is 75 percent gas and 25 percent alcohol, it would make sense that you will drop 25 percent off your HC emissions. I have done this trick myself and it brings down the HC emissions alot. It looks like you dont have to come down very much at all, this should do it. Its one of the favorite BC Aircare tricks. The gallon of Meth is about 10 bucks at your parts store. After you pass go straight to the gas station and fill up to dilute it.