Check Exhaust Manifold Restriction

^ Remove the exhaust manifold and inspect ports for casting flash by dropping a length of chain into each port.

NOTE: Do not use a wire or a lamp to check ports. Restriction may be large enough for wire or light to pass through but small enough to cause excessive back pressure at high rpm.

^ Is the manifold free of casting flash?

YES -- Return to Diagnostic Routines.

NO -- Replace the exhaust manifold. Go to Rerun Exhaust Emission Test. Rerun Exhaust Emission Test