High HC on smog test

[emolina]

1997 4.0 SOHC with 114,390 miles. Almost failed smog due to high HC. Here are the results.

At idle (RPM=689): %CO2=14.6, %O2=0.4, HC=92, %CO=0.32
At RPM=2377: %CO2=14.6, %O2=.5, HC=35, %CO=0.25

Replaced spark plugs and wires 2 years and 9,000 miles ago. O2 sensor replaced 2 years ago when it threw a code. Cleaned the MAF two days before the test.

What might be the cause of the high HC?
Thanks for your help.

 

[koda2000]

have you ever replaced your o2 sensors? if you stick your finger in the tail pipe and rub the side, does it come out black and sooty? were you due or overdue for an oil change just before the emissions test? is your engine temp normal?

 

[emolina]

O2 sensor replaced. Oil changed 3 days before test. I'll check the tailpipe for oil but it looks clean.

 

[Tbars4]

..You should be able to find a useful link at the top of the first post of this thread...

http://www.explorerforum.com/forums/showthread.php?t=219411&highlight=smog