Honda Car Forum

Failed inspection 1st time so I poured in a bottle of fuel cleaner (premium gas) and run off 3/4 tank of gas.

It failed again (NOX) by a small margin. I was advised to use up at least 2 cycles of of my gas tank before bringing it in again. Did that (poured in 2 bottles of cleaner and filled tank with premium gas) but it failed the 3rd time. and the margin of failure was worst than the 1st.

Swapped out the EGR valve and oxygen sensor but it failed the 4th time.

A mechanic performed a vacumn test on the line going into the EGR valve. Since engine did not studder he concluded that the EGR ducts in the manifold was clogged.

I took out the intake manifold. The 4 ducts leading into the cylinders coated with gunk but that was easily cleaned up.

The duct leading from the EGR port and branches to a small hole at the top of each manifold cylinder was a different story. Due to lack of access i can only pour in carb cleaner. How do i verify that its already unblocked?

In an earlier posting someone mentioned that those ports need to be drilled and some port pulled out with a sliding hammer.

1993 Accord LX wagon automatic - Engine hesitation/misfire

Does this apply here?