Chapter 1 Tune-up and routine maintenance
44.10 Loosen the distributor attaching/hold-down nut (arrow)
and turn the distributor to adjust the ignition timing
46.2 Detach the altitude compensator for access to the solenoid
air valve cover (arrow)
(see illustration). Do this before starting the engine to check the ignition
timing.
8 Make sure the wiring for the timing light is clear of all moving engine
components, then start the engine. Race the engine two or three times,
then allow it to idle for a miqute.
9 Point the flashing timing light at the timing iarks, again being careful
not to come in contact with moving parts. The marks you highlighted
should appear stationary. If the marks are in alignment, the timing is cor-
rect. If the marks aren’t aligned, turn off the engine.
10 Loosen the distributor attaching/hold-down bolt/nut until the distribu-
tor can be rotated (see illustration).
11 Startthe engine and slowly rotate the distributor either left or right until
the timing marks are aligned.
12 Shut off the engine and tighten the mounting bolt/nut, being careful
not to move the distributor.
/
13 Restart the engine and recheck the timing to make sure the marks are
still in alignment.
14 Disconnect the timing light and jumper wire.
15 Race the engine two or three times, then allow it to run at idle. Re-
pheckthe idle speedwith the tachometer. If it haschangedfrom the correct
setting, readjust it (carbureted models only).
16 Drive the vehicle and listen for “pinging” noises. They’ll be noticeable
when the engine is hot and under load (climbing a hill, accelerating from a
stop). If you hear engine pinging, the ignition timing is too far advanced
(BeforeTop Dead Center). Reconnect the timing light and turn thedistribu-
tor
to move the mark 1 or 2-degrees in the retard direction (counterclock-
wise). Road test the vehicle again to check for proper operation.
45.2 Locate the EGR valve (arrow) and check the hoses leading
to it for damage
46.3 Solenoid valve air filter details
17 To keep “pinging” at a minimum, yet still allow you to operate the ve-
hicle at the specified timing setting, use gasoline of the same octane at all
times. Switching fuel brands and octane levels can decrease performance
and economy, and possibly damage the engine.
45 Exhaust Gas Recirculation (EGR) system check
Refer to illustration 45.2
1 The EGR valve is located on the intake manifold. Most of the time,
when a problem develops in the emissions system, it is due to a stuck or
corroded EGR valve.
2 With the engine bold to prevenfburns, check the EGR valve hoses for
damage (see illustration). Pull the hoses off and inspect for clogging.
3 If the hoses are cracked or clogged, replace them with new ones.
4 Refer to Chapter 6 for more information on the EGR system.
46 Solenoid valve air filter replacement (1985 through
1989 models)
Refer to illustrations 46.2 and 46.3
.
1 The solenoid valve air filter on 1985 through 1989 niodels must be re-
placed at the specified intervals or it will become clogged, causing rough
idling. The solenoid valve is located in the engine compartment on the driv-
er’s side inner fender, under a cover.
2 Remove cover for access (see illustration).
3 Pull the filter out of the assembly and push a new one securely into
place (see illustration).
47 Oxygen sensor replacement
1 The oxygen (exhaust gas) sensor used on later models should be re-
placed at the specified intervals.
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