Tune-Up - v6 Pontiac Firebird III

VEHICLE IDENTIFICATION NUMBER CODE

Engines may be identified by the 8th character of Vehicle Identification Number (VIN). The VIN is located at the left front corner of instrument panel and is visible through windshield.

VIN ENGINE CODES

TUNE-UP NOTES

Note. When performing tune-up procedures described in this article, the following notes and precautions must be followed

Due to late changes and corrections, always refer to Engine Tune-Up Decal in engine compartment before tune-up. If manual and decal differ, always use decal specifications.

With the exception of initial ignition timing, normal tune-up adjustments are not required. Perform adjustments only when indicated by the Computer Command Control (CCC) System Performance Check, CCC diagnostic charts and/or poor engine performance.

Do not allow or create a condition of engine misfire in more than one cylinder for an extended period of time. Damage to catalytic converter may occur due to loading converter with unburned air/fuel mixture.

Before making a compression test or cranking engine with a remote starting switch, disconnect ignition switch "BATT" terminal lead at distributor.

Do not add fuel system cleaning agents to fuel tank or carburetor as they can damage the catalytic converter.

Do not remove spark plug wires with engine running. HEI secondary voltage may inflict harmful electrical shock.

Damage to HEI electronic module and/or ignition coil may result if "TACH" terminal in distributor cap connector is grounded.

ENGINE COMPRESSION

Test compression pressure with engine at normal operating temperature. Remove all spark plugs. Set throttle and choke valves wide open.

COMPRESSION SPECIFICATIONS

SPARK PLUGS

SPARK PLUG TYPE

SPARK PLUG INSTALLATION

HIGH TENSION WIRE RESISTANCE

Carefully remove ends of wire from spark plug and distributor. Using an ohmmeter, check resistance while gently twisting wire. If resistance is not to specification or fluctuates, replace wire.

WIRE RESISTANCE (OHMS)

FUEL PUMP

Make all tests at slow idle speed. For models with fuel return line, pinch off return line. For vacuum test, connect vacuum gauge to inlet side of pump.

FUEL PUMP PERFORMANCE

Distributor

All models equipped with distributors use a Delco-Remy High Energy Ignition with Electronic Spark Timing (HEI-EST).

PICK-UP COIL RESISTANCE (OHMS)

IGNITION COIL RESISTANCE (OHMS)

Note. Procedures and specifications for 3.0L (VIN L) and 3.8L (VIN B, 3 & 7) engines are not available from the manufacturer.

1. Connect ohmmeter between ignition coil primary and coil frame. Reading should be infinite on high scale of meter. Disconnect ohmmeter from coil frame and connect it to the other coil primary terminal. Reading should be very low or zero on low scale of meter.
2. Disconnect ohmmeter lead from one of the coil primary terminals and connect it to coil secondary terminal. Reading should not be infinite on high scale of meter.

Note. For more information on ignition system, see DELCO-REMY COMPUTER CONTROLLED COIL IGNITION or DELCO-REMY ELECTRONIC SPARK TIMING (EST) IGNITION in ELECTRICAL section.

VALVE CLEARANCE

VALVE CLEARANCE ADJUSTMENT

2.8L

1. E-I-I-E-I-E (Left bank - Front-to-rear).
2. E-I-E-I-I-E (Right bank - Front-to-rear).

3.0L, 3.8L & 4.3L

1. E-I-E-I-I-E (Left bank - Front-to-rear).
2. E-I-I-E-I-E (Right bank - Front-to-rear).

Starting with 1987 models, 2.8L (VIN S, W or 9) engines are equipped with the C(3)I Ignition System. This system uses: a 3-coil module along with a crankshaft reluctor and a block mounted magnetic sensor instead of a distributor.

The 3.0L MFI (VIN L) and 3.8L SFI (VIN 3 and 7) engines are equipped with C(3)I ignition. The system uses a 3-coil module with crankshaft and camshaft sensors in place of a distributor.

Models that use a distributor are equipped with the High Energy Ignition (HEI) system with Electronic Spark Timing (EST).

2.8L Firing Order. Scheme 9

3.8L (VIN A) Firing Order & Timing Marks. Scheme 10

3.0L MFI & 3.8L SFI Firing Order. Scheme 11

4.3L TBI Firing Order & Timing Marks. Scheme 12

IGNITION TIMING

Note. Engines are equipped with receptacle for a magnetic timing probe timing meter, located at 9.5° ATDC. Do not use receptacle for timing with conventional light. Timing adjustment is not required on 2.8L (VIN S, W or 9) with Direct Ignition System (DIS), or 3.0L (VIN L) and 3.8L SFI (VIN 3 and 7) engines with Computer Control Coil Ignition (C(3)I) ignition.

1. Engine must be at normal operating temperature. Turn off all accessories and A/C.
2. On 4.3L (VIN Z), with TBI, "CHECK ENGINE" light must be off. On all engines, put HEI-EST in by-pass mode by unplugging "Set Timing" connector.
3. On 2.8L (VIN S, W & 9) with MFI and 4.3L (VIN Z) with TBI, "CHECK ENGINE" light must be off. On 2.8L engine, cooling fan must be off. On all engines, put HEI-EST in by-pass mode by unplugging "Set Timing" connector.
4. "Set Timing" connector is a Tan/Black wire which breaks out of the engine wire harness near the distributor. On some vehicles, "Set Timing" connector may be on the firewall near blower motor housing. DO NOT unplug 4-wire connector at the distributor. Place Automatic transmission (if equipped) in "D". Adjust timing at engine idle. Clear ECM trouble code after adjustment.
5. On 3.8L (VIN A), verify if "CHECK ENGINE" light is not on. Disconnect 4-wire connector at distributor. "CHECK ENGINE" light will come on. Place automatic transmission (if equipped) in "D". Adjust timing with engine at idle. Reconnect 4-wire distributor connector. Clear ECM trouble code after adjustment.

IGNITION TIMING SPECIFICATIONS

HOT (SLOW) IDLE RPM

Note. On fuel injected models, engine idle speed varies. This fluctuation is considered normal, and should not be adjusted unless throttle body components have been replaced.

MFI, SFI & TBI

1. On 2.8L (except for VIN 9), 3.0L and 3.8L engines, use an awl to pierce minimum idle stop screw cover. Apply leverage to remove cover. On all engines, ground ALDL diagnostic test lead.
2. Turn ignition on, but do not start engine. Wait 30 seconds. Disconnect Idle Air Control Valve (IACV) harness connector. Remove ALDL diagnostic test lead ground and start engine. Place auto. trans. (if equipped) in "D".
3. Adjust minimum idle stop set screw to specification. See «MINIMUM THROTTLE BODY IDLE SPEED»(/pontiac/firebird/iii-1982-1992/remont/adjustments/#tune-up-v6) chart. After adjustment, turn ignition off and reconnect IACV connector. Clear any trouble codes.

MINIMUM THROTTLE BODY IDLE SPEED

Scheme 13

Scheme 14

1. Remove plunger. Measure and record length of plunger (distance "A"). (Scheme 13) Install plunger into ISC and position so that distance measured from back side of plunger to ISC is less than distance "B". See «IDLE SPEED CONTROL PLUNGER SETTING»(/pontiac/firebird/iii-1982-1992/remont/adjustments/#tune-up-v6) chart.
2. Place transmission in Neutral (man. trans.) or in "P" (auto. trans.). Set brakes and block wheels. Connect tachometer to engine. Connect dwell meter to mixture control solenoid (Green) lead. Set dwell meter on 6-cylinder scale. Turn A/C off (if equipped). IDLE SPEED CONTROL PLUNGER SETTING Application Dimension "A" In. (mm) Dimension "B" In. (mm) 3.8L (VIN A) 41/64" (16.3) 5/16" (8.0) (Scheme 13): Measuring Idle Speed Control Plunger
3. Start engine. Run until engine enters "Closed Loop" operation (dwell meter needle starts to fluctuate). Stop engine. CAUTION: DO NOT disconnect or connect ISC connector with ignition in the "ON" position or damage to ECM may result.
4. Unplug ISC connector from motor. Retract plunger by applying 12 volts to terminal "C" and grounding terminal "D" of ISC motor. (Scheme 14) DO NOT leave 12 volts connected to ISC motor any longer than necessary to retract plunger. (Scheme 14): Idle Speed Control Adjustment Connections CAUTION: NEVER connect a voltage source across terminals "A" and "B" or internal throttle contact switch will be damaged.
5. Start engine and run until dwell meter starts to vary (Closed Loop operation). Place transmission in "D" (auto. trans.). With plunger fully retracted, adjust carburetor slow idle screw to Minimum Authority Idle RPM. With idle adjusted, place transmission in "P".
6. Extend ISC plunger by applying 12 volts to terminal "D" and grounding terminal "C" of ISC motor connector. (Scheme 14) Place transmission in "D" and adjust plunger to Maximum Authority Idle RPM. Recheck adjustment RPM by applying voltage to extend plunger (plunger will ratchet at full extension).
7. After adjustment, recheck distance "B". (Scheme 13) Distance must not exceed specified dimension. MINIMUM & MAXIMUM AUTHORITY IDLE RPM Application Minimum Maximum 3.8L 2-Bbl. (VIN A) 450 900
8. Retract plunger and turn engine off. Disconnect all test equipment and wires. Ensure ignition is off. Reconnect ISC motor 4-terminal connector. Clear diagnostic trouble code by removing ECM fuse from fuse block.

THROTTLE POSITION SENSOR

1. On E2ME carburetors, use a 5/64" drill bit to drill a hole in the steel cup plug covering the TPS adjustment screw. (Scheme 15) Do not damage adjustment screw head.
2. On all models, unplug TPS connector. Jumper all 3 sensor terminals to harness. Connect a high impedance digital voltmeter to TPS terminals "B" and "C".
3. With ignition on and engine stopped, A/C off, and throttle in specified position, turn TPS adjusting screw until correct voltage is reached. Remove jumpers and reconnect harness.

TPS ADJUSTMENT VOLTAGE

E2ME Idle Air Bleed Valve Location. Scheme 15

Idle Air Bleed Valve Adjustment (Remove Gauge To Complete Adjustment On Vehicle). Scheme 16

IDLE MIXTURE ADJUSTMENT

Note. Idle mixture should only be adjusted if vehicle fails testing or carburetor has been disassembled. MFI, SFI or TBI fuel injection models cannot be adjusted.

MIXTURE SCREW PLUG REMOVAL

1. Remove carburetor from engine, invert carburetor and drain fuel into a container. Place carburetor on a holding fixture up-side down.
2. Use hacksaw to make 2 small cuts below mixture plugs on bottom of throttle body. Use flat punch or chisel to break out a piece of throttle body to gain access to plugs.
3. Use a punch to drive out plug. If hardened steel plug shatters, remove loose pieces. Repeat last 2 steps to remove remaining plug (if equipped).

E2ME Carburetor

1. Mixture control solenoid plunger travel should be checked before adjustment. Stop engine and remove air cleaner and gasket. Insert Float Gauge (J-34935-1 or BT-8420-A) in "D" shaped hole in air horn (next to idle air bleed valve cover). It may be necessary to grind material off gauge to allow it to enter the vent hole.
2. Press down on gauge to determine travel of plunger. Total movement should be 2/32-6/32" (2.4-4.8 mm). If solenoid movement is not correct, carburetor must be disassembled and adjusted. See ROCHESTER E2ME 2-BARREL in FUEL SYSTEMS section. If solenoid movement is correct, proceed to step 3).
3. Set parking brake and block drive wheels. Disconnect and plug canister purge hose. Connect tachometer. Check ignition timing and adjust if necessary.
4. Connect a dwell meter to Green wire from mixture control solenoid in carburetor. Set dwell meter on 6-cylinder scale. Start engine and run at idle until normal operating temperature is reached and a varying dwell is noted on dwell meter. NOTE: Run engine long enough to ensure engine coolant sensor and oxygen sensor are at full operational temperature.
5. Adjust curb idle speed (on models with ISC, do not adjust). With engine idling in Neutral (man. trans.) or "D" (auto. trans.), observe dwell reading. If dwell needle is moving within 10-50°, no adjustment is necessary. If needle is fixed at one point or outside this range, see SYSTEM PERFORMANCE CHART in COMPUTER CONTROLS article in COMPUTER CONTROLS section. Return to next step if flow charts indicate carburetor adjustments, calibration or service are necessary.
6. With engine stopped, cover carburetor air intakes and vents with tape. Drill rivet heads on idle air bleed cover (above primary bores). Remove plug and blow out metal chips and rivet pieces.
7. Install Air Bleed Valve Gauging Tool (J-33815-2 or BT-8253-B) in "D" shaped hole on throttle side of air horn. Position gauge so upper end is over open cavity next to idle air bleed valve. (Scheme 16)
8. Lightly hold gauge down to seat solenoid plunger against its stop. Adjust idle air bleed valve so that gauge will pivot over and just touch top of valve. Remove gauge. CAUTION: The idle air bleed valve is very sensitive. It should be turned only in 1/8 turn increments.
9. If after performing this adjustment, the dwell reading does not vary and is not within the 25-35° range, it will be necessary to remove plugs covering the idle mixture screws.
10. Turn mixture screws in until lightly seated. Back screws out 3 turns. Reinstall carburetor with new flange gasket. Disconnect and plug canister purge hose. Bring engine to normal operating temperature and check dwell.
11. While idling in Drive (Neutral for manual transmissions), adjust mixture needles equally until dwell reading is within 25-35°. Dwell should be as close to 30° as possible. Allow reading to stabilize after each adjustment.
12. Seal idle mixture screws with silicone sealant or RTV. Reset idle speed on models without ISC. Remove test equipment and reconnect all hoses.

3.8L 2-Bbl.

With engine off, place throttle on high step of fast idle cam. Disconnect and plug EGR valve vacuum hose. Start engine without touching throttle and adjust fast idle speed.

FAST IDLE SPEED (RPM) (1)

AUTOMATIC CHOKE

No adjustment is necessary or possible.

FUEL SYSTEM

CARBURETORS

FUEL INJECTION

BATTERY

BATTERY SPECIFICATIONS

STARTER

All models are equipped with a Delco-Remy solenoid actuated starter with overrunning clutch.

STARTER SPECIFICATIONS

ALTERNATOR

All models are equipped with Delco-Remy alternators with integral voltage regulators.

ALTERNATOR SPECIFICATIONS

ALTERNATOR REGULATOR

All use a Delco-Remy non-adjustable voltage regulator integral with alternator.

REGULATOR OPERATING VOLTAGE

SERVICE INTERVALS

To reset "Service Interval Light" used on Pontiac 6000 STE with Driver's Information Center (DIC), proceed as follows: With service item displayed, press and hold down the reset button. The distance between service intervals will decrease at a rate of 500 miles every 5 seconds. The reprogrammed distance to next service interval will be displayed when button is released. When the mileage interval reaches zero, the service item will light up. Repeat this operation to reset each service item (if required).

If the service interval light for each item is reset within 10 miles of coming on, the light will go out immediately. If the service interval light is left on longer than 10 miles, the display will remain on for 10 miles before going out.

REPLACEMENT INTERVALS

BELT ADJUSTMENT

BELT ADJUSTMENT

CAPACITIES

COOLING CAPACITIES

ENGINE OIL & FUEL CAPACITIES

TRANSMISSION & DIFFERENTIAL CAPACITIES

SYSTEM REFRIGERANT CAPACITIES

See also:
• MINIMUM THROTTLE BODY IDLE SPEED