Charlie:
I just failed the bi-annual California emissions test on my '89 L-Jet
Spider for marginally high CO at 25mph. Here are the results:
2801 @15mph, Max CO Allowed 0.78%, Measured CO 0.78% PASS
2870 @25mph, Max CO Allowed 0.66%, Measured CO 0.78% FAIL
The other tests (HC, NOx) passed and actually get better with speed, so
the
catalytic convertor is working.
Have you done anything on the car since the last time it was tested? Does
it seem to otherwise be running just fine?
They way the L-Jet system is designed, it should be correcting the mixture
if the O2 sensor is working correctly--even if some other factors are off.
Here are some things to consider:
- With a working O2 sensor and everything else in working order, if the
converter isn't working properly you'll still get measurable CO and HC
emissions.
- With the O2 sensor NOT working and everything else--including the
converter--in working order, you should see almost no CO or HC emissions.
With a solidly working converter, the mixture *can* be ever-so-slightly rich
and the car will still produce little CO or HC.
I'd suggest putting in a new air filter, checking the O2 sensor and having
the converter checked.
With the car warmed up and idling, disconnect the O2 sensor, place the
positive lead of a VOM on it, and the negative lead on a good ground. You
should see a varying signal around 0.5 volts. If the signal doesn't vary,
the sensor is shot. If the voltage is high (meaning the mixture is rich),
then there is either something wrong with the engine or the sensor is shot.
If it shows a low voltage but the engine isn't stumbling, the sensor is
shot. If the signal high and varies, I'd trust that the engine IS rich and
pursue that problem.
If you take the car to a shop with an emissions tester, they can put the car
on a lift, running, and check the emissions level in front of the converter
through the O2 sensor's mounting boss. Then, they can burn a small hole
through the pipe just after the converter and check the emissions there.
(They'll close the hole when they're done.) That will tell whether the
converter is working. And that is the only valid test that I know of.
Rich Wagner
Montrose, CO, USA
'82 GTV6
--
to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi
or email "unsubscribe alfa" to [email protected]
