Emissions Test
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New User
Joined: Jul 2001
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Emissions Test
I have an 82 Bronco with a stock 300 that passed the Md emissions test 2 years ago. My number just came up again and the truck failed for hydrocarbons. I did all the tune up stuff (plugs,wires,pcv valve,air cleaner, timing,idle speed) and took the truck back and it failed again for hydrocarbons. I seem to recall over the years hearing about some things that could be done to ensure passing these tests, but my memory fails me. Any suggestions?
Posting Guru
Joined: Mar 2001
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Emissions Test
You could try leaning the heck out of it (just for the test). I've read that changing the oil a few times can help flush out some of the built up nastities and allow the fresh oil to absorb some of the HC's before they get out of the engine.
Elder User
Joined: Apr 2001
Posts: 772
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From: Glen Burnie Maryland
Emissions Test
Jason;
Did you try and get a waiver based on parts purchased and work done. I live in Md too. Also did they run the treadmill or the static test.
Hydrocarbons usually indicate running richer than specifications.
Couple of things you might want to try.
1st; Make sure your temps are UP! Drive it for NO LESS THAN 30 Minutes before testing. Preferably on Interstate or Beltway. Cold engine will run richer.
2nd; Lean out the mixture with the mixture screw (pop off the metal cover and turn down 1/8 turn at a time until idle speed starts to drop. Back off 1/8 turn.
Your cats might also be starting to get plugged causing the engine to run poorly and rich. (your standing on the gas harder and the exhaust system is restricting flow.)
Double check your timing, spark plug gaps, PCV Valve and vacuum hoses.
Larry
Did you try and get a waiver based on parts purchased and work done. I live in Md too. Also did they run the treadmill or the static test.
Hydrocarbons usually indicate running richer than specifications.
Couple of things you might want to try.
1st; Make sure your temps are UP! Drive it for NO LESS THAN 30 Minutes before testing. Preferably on Interstate or Beltway. Cold engine will run richer.
2nd; Lean out the mixture with the mixture screw (pop off the metal cover and turn down 1/8 turn at a time until idle speed starts to drop. Back off 1/8 turn.
Your cats might also be starting to get plugged causing the engine to run poorly and rich. (your standing on the gas harder and the exhaust system is restricting flow.)
Double check your timing, spark plug gaps, PCV Valve and vacuum hoses.
Larry
