Idle System 2Gc Except California; Choke Check Procedure; Idle Speed Adjustment - Pontiac TRANS AM 1977 Service Manual

6C-24
1977
PONTIAC SERVICE M A N U A L
*
E.G.R. (EXHAUST GAS
TIMED
RECIRCULATION)
CANISTER
RESTRICTION
"E.G.R. TUBE
DISCHARGE
PORTS
HOLE THROTTLE
VALVE
4560
Fig. 6C-4 1 ldle System 2GC Except California
connection, cracking, abrasion or deterioration and correct
or replace as necessary.
Choke Check Procedure
1. Remove air cleaner. With engine off, hold throttle half
open. Open and close choke several times. Watch linkage to
be certain all links are connected and there are no signs of
damage.
2. If choke or linkage binds, sticks or works sluggishly,
clean with United Delco Choke Cleaner X-20-A or
equivalent. Use cleaner as directed on can. If cleaning does
not correct, replace binding parts.
3. Visually inspect carburetor to be certain all vacuum
hoses are connected. Inspect hoses for cracks, abrasion,
hardness or signs of deterioration. Replace or correct as
necessary.
4. Make sure vacuum break diaphragm shafts are fully
extended when engine is off. If shafts are not fully extended,
replace vacuum break assembly. Start engine, primary
vacuum break diaphragm shaft should fully retract. If unit
fails to retract, replace vacuum break assembly.
Electric Choke
If the electric choke fails to open, the following checks
should be made:
1. Check voltage at the choke heater connection with the
engine running. If voltage is between 12 and 15 volts, replace
the electrical choke unit.
2. If the voltage is low or zero, check all wires and
connections. If the connection at the oil pressure switch is
faulty, the temperature pressure warning light will be off with
the key "on" and the engine not running. Repair wires as
required.
3. If steps 1 & 2 check OK, replace oil pressure switch.
ADJUSTMENTS
ldle Speed Adjustment
Refer to Vehicle Emission Control Information label on
vehicle for latest certified specification information.
1. With engine at normal operating temperature, choke
full open, and air conditioning OFF, connect a tachometer
to engine.
2. Set parking brake and block drive wheels.
3. Disconnect and plug hoses from vapor canister and
EGR valve.
4. Start engine and position transmission in PARK or
NEUTRAL.
5. Disconnect vacuum advance hose and set ignition
timing at specified rpm.
6. Reconnect advance line and adjust idle speed.
8. Unplug and reconnect hose from vapor canister and
EGR valve.
8. Shut off engine and remove tachometer.
Carburetor Adjustments
Refer to Figs. 6C-52 thru 55 for carburetor adjustment
procedures and specifications.