Michael Jose wrote:
>
> My '79 doesn't pass emission, and they say the CO is high, and likely
High CO and High HC - Running rich. Lean it out.
Be careful too lean and you'll have lean misfire (in which case you'll
have high HC and low CO).
Also as you lean it it will become harder to ignite. So you may want to
go over the ignition system (good coils, wires and plugs) so that the
spark is strong (a nice fat spark is needed). Poor ignition will cause
high HC and either high or low CO (depending on mixture strength), you
also may get a high oxygen reading.
High idle speed (if the state allows it) and a tight leak free exhaust
system will also help. Both of these help remove the exhaust from the
cylinder. Exhaust remaining in the cylinder dilutes the fuel-air
mixture and make it harder to ignite (again high HC). Along this vane
make sure the EGR valve is seating well. You may want to disconnect the
EGR vacuum control for an idle test (but I never said that).
Dieseling and overheating can both be caused by too advanced ignition
timing. Retarding the timing usually lowers the CO (by allowing
combustion to continue in the exhaust).
While in theory a vehicle tuned for low emissions should run fine (other
than possible lean operation when opening the throttle due to poor
carburetor designs) it ain't necessarily so. If the clean tuning causes
poor performance return the setting to where they were (I never said
this either).
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