emissions test

|I will be taking my truck for inspection next month (Texas). Last year it |failed NOX test-all other passed. I was able to get 1 year exemption. | | I replaced EGR valve last year (after failing first test), but still failed |NOX. I believe carbon buildup is main cause of failing the emissions test, |but don't know this for sure. The truck runs well. I don't drive it much |anymore, which could be cause of carbon buildup. It has low mileage for the |truck's age. | |Any suggestions on how to pass the NOX test, or how to reduce carbon |buildup? Mechanics have quoted $300-$500 to remove & clean intake |manifold-too much for an old truck. | |Thanks | |1982 F100, 302 V8 |131000 miles-purchased new in '82

Berryman's makes a couple of kits for that purpose. I haven't used them but we started selling the heck out of them when the new testing came in in January.

Product # 2610 TOTAL COMBUSTION SYSTEM CLEANER KIT - POURIN

-------------------------------------------------------------------------------- Formulated with High Energy Solvent Technology (H.E.S.T.) to clean the intake valve and combustion chamber. One treatment provides two instant emission improvements! Total Combustion System Clean-Up removes preformed deposits in the combustion chamber, reduces intake valve and port deposits and prevents recurring deposits. Enhances performance, reduces maintenance and improves hydrocarbon and carbon monoxide emissions. High Energy Solvent Technology (H.E.S.T.) Sizes Available:

2610 NET 16 fl. oz. Pour Can Line Art

Products 2616 B-12 CHEMTOOL® TOTAL FUEL SYSTEM CLEAN-UP (T.F.S.C.) - POURIN

-------------------------------------------------------------------------------- Formulated with High Energy Solvent Technology (H.E.S.T.) and state of the art detergent to maximize and accelerate the cleaning of intake valves, fuel injectors and combustion chambers. TFSC attacks carbon deposits in the entire fuel system to help restore peak performance, improves starting, driveability and gas mileage. One application is good for 3000 miles. High Energy Solvent Technology (H.E.S.T.) Sizes Available:

2616 NET 16 fl. oz. Long Neck Aluminum Bottle (NOTE: Also available as part of kit #2620)

Let me know if theses help. I have the same problem on my '94

Rex in Fort Worth

Here's what I do to pass the emissions test in my 67 F-100 352:

• Timing at 5 BTDC (should be 8)

• Very lean fuel mixure

• New plugs and wires

• No vacuum leaks

• New oil and filter

• New or cleaned air filter

• New PCV valve

• Add one gallon of denatured alcohol to 18 gallons of fuel

• High idle speed

• 3 Hail Mary's a 4 Glory Bes Good luck jor

Retarding the timing will reduce NOx levels , maybe enough to pass the test. It will probably run like crap but you could always put the timing back after the test. You can also try a lower temperature thermostat.

High NOx levels are caused by high combustion temperatures. Many things can cause this such as a lean mixture , too advanced timing malfunctioning EGR sytem, all of which often give higher HC levels due to misfire.

I heard some good things about Chevron Techron for dealing with carbon buildup. Can't say for certain if its effective or just another snake oil.

update- After failing the first emissions (NOX) test, I did the following;

-spark plugs, wires, dist. cap & rotor

-air cleaner, PCV valve

-oil change

I also removed the EGR valve, which was replaced last year, and discovered there was a lot of carbon buildup on one port. I cleaned this as best I could. I also started the engine with EGR valve removed to blow out some carbon.

As a result, I passed the emissions test. Actual emissions measurements were actually quite good.

I believe the carbon buildup was the primary cause of NOX failure, and cleaning and blowing out some of the carbon enabled the EGR valve to function as it should. I should also note that when I reinstalled the cleaned EGR valve, the engine ran much smoother.

High NOx levels are caused by high combustion temperatures. Many things can cause this such as a lean mixture , too advanced timing malfunctioning EGR sytem, all of which often give higher HC levels due to misfire.

I heard some good things about Chevron Techron for dealing with carbon buildup. Can't say for certain if its effective or just another snake oil.