91 Accord LX Emissions Failure HC - Fixed

[PeteCz]

My 1991 Honda Accord LX 4 Cyl with ~250,000 miles failed Maryland emissions test for Hydrocarbons (HC). Failed emission test 3 times with hydrocarbons of 3.2, 1.5 and 2.2 GPM (Grams Per Mile) vs spec of 1.0 max. I tuned up car (spark plugs/wires, distributor cap, rotor, igniter, coil, air filter, and timing). Car still failed emissions hydrocarbons with 2.2 GPM on 3rd try. After 3rd try another mechanic diagonsed that the the EGR Manifold ports 2,3, and 4 were completely clogged. EGR gasses were only being directed to number 1 cylinder. Car accelerated smoothly but hesitated when maintaining speed at about 40 - 45 MPH (2000 - 2500 RPM). Seemed like timing was off, but number 1 cylinder/plug was not firing properly due to input of all EGR gases. EGR System is not active during acceleration explaining the car accelerated so smoothly but hesitated at constant speed.

Took to dealer and had the EGR manifold metal sealing plugs removed, ports/manifold cleaned and new metal sealing plugs installed. Car passed emission test (4th try) with flying colors (0.04 Grams Per Mile Hydrocarbons). Surprising that catalytic converter did not need replacing. Have never replaced catalytic converter. Also had significant reduction in CO (9.37 to 0.42), NOX (0.81 to 0.08), and CO2 (310.80 to 35.65) Gram Per Mile levels on 4th try.

Hope this can help someone pass HC emission tests. Sure was nice seeing the "Fast Pass" sign on the emissions monitor during the test.

[davidis1]

Heard in another thread that it is possible to clean EGR ports via access under the fuel rail. Sounds like this is where I am headed. Thanks for the great post.