elevated HC reading in '95 Camry V6

Yesterday my '95 Camry V6 passed its seventh smog test in a row.
But the HC reading was 83 at 15 mph. The max permissible is 84.
Two years ago it was half. All other tests were fine. The car is
very
seldom driven. Could that be the problem? What needs be done?
Gas additive? Long trip? ... ?

Thanks, Jake

High HC means you have unburned fuel in the exhaust. Retarded timing
(stretched timing belt), valve gap off spec, old spark plugs, vacuum
leaks, valve carbon buildup, etc etc can contribute. Oxygen sensors
can also be the culprit. Use Bosch *planar* type if necessary. These
newer designs are more resistant to contamination. Oxygen sensors,
like spark plugs, are actually wear items. The minute amounts of
sulfur in the gas (plus other combustion contaminants) will gradually
degrade the performance.

http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2

But if it's seldom driven then first try Chevron Techron fuel system
cleaner with fresh tank of gas (gas deteriorates fairly quickly
sitting around). However, with a dirty tank it may dislodge buildup
and may require you to change the fuel filter. But as general
maintenance a fuel filter should be replaced if you haven't done it
since 95. I don't believe the lifetime fuel filter, ATF, coolant type
of marketing. But "lifetime" means different things to manufacturers
and owners.



On Dec 9, 7:48 pm, wrote:
> Yesterday my '95 Camry V6 passed its seventh smog test in a row.
> But the HC reading was 83 at 15 mph.  The max permissible is 84.
> Two years ago it was half.  All other tests were fine.  The car is
> very
> seldom driven.  Could that be the problem?  What needs be done?
> Gas additive?  Long trip? ... ?
>
> Thanks, Jake