Why did you replace your DPFE for HC? The DPFE is a EGR component that takes care on NOx, not HC. I have an old Hot Rod tech article that states the following:
"Gasoline consists of hydrogen and carbon atoms, thus levels of hydrocarbon represent unburned fuel in the exhaust. Mistakenly thought of rich air/fuel(A/F) mixture, HC is known as a misfire meter. HC levels escalate when the engine is not experiencing complete and efficient combustion. Residual HC is created by ignition problems, excessively lean A/F mixtures, camshaft design, and excessive crevice volumes or carbon deposits in the combustion chamber."
BigJim explained that some cats only reduce NOx, while oxidation catalysts take care on HC and CO. Contiques cats probably are dual-bed or three-way catalysts that take care of all three emissions "culprits".
So my point is to double check the ignition and the fuel delivery systems before maybe needlessly replacing your cat(s). BTW before replacing my DPFE and doing some other stuff only my NOx levels were elevated.
1st attempt CA emissions test results
@ 15mph 14.91 CO2(%)
0.02 02(%)
9 HC (ppm) (55 max)
0.01 CO(%) (0.50 max)
935 NOx (ppm) (437 max)FAILURE
2nd attempt CA emissions test results
@ 15 mph 14.9 CO2
0.1 02
7 HC
0.01 CO
44 NOx
I think this shows that HC should be alot lower than 220ppm.
