the code P1491 pops up in the system. I replaced and even cleaned out the egr valve really good, reset the check engine light and it still will not pass smog. What can I do? The smog tech said that everything looks good in my emissions and my engine but that code still pops up. Now my check engine light is back on again.
why Will my car not pass smog? on 1996 Acura TL
The egr ports inside your intake manifold are probably clogged, it may have to be removed to thoroughly cleaned. Or it may be a problem with the egr control solenoid.