ENGINE MECHANICAL
Note. The Assembly Line Data Link (ALDL) connector may also be referred to as the Data Link Connector (DLC). The SERVICE ENGINE SOON (SES) light may also be referred to as the Malfunction Indicator Light (MIL).
Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.
VALVE CLEARANCE
Note. All models use hydraulic lifters. No adjustments are required.
4.3L WITH DISTRIBUTOR
- Set parking brake, block drive wheels and place transmission in Neutral or Park. Warm engine to normal operating temperature. Turn A/C off (if equipped). Ensure Malfunction Indicator Light (MIL) is off.
- Disconnect Tan/Black Electronic Spark Timing (EST) by-pass connector wire. DO NOT disconnect 4-wire connector at distributor.
- On models where engine computer is located underhood, on right fenderwell, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness near engine computer harness connectors.
- On models where engine computer is located in passenger compartment under right side of instrument panel, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness where heater box and carpet meet on passenger side floor. Pull back carpet to expose single Tan/Black wire and connector on outside of control module harness.
- On all models, connect timing light to No. 1 spark plug wire. Check timing and adjust if necessary. See «IGNITION TIMING»(/chevrolet/caprice-impala-ss/1995-1996/remont/adjustments/#engine-controls-adjustments-43l) . Reconnect EST by-pass connector. Clear Diagnostic Trouble Code (DTC).
4.3L WITH DIS
Ignition timing is not adjustable.
| Application | Man. Trans. | Auto. Trans. |
|---|---|---|
| With Distributor | 0 @ Idle | 0 @ Idle |
| Distributorless | (1) | (1) |
| (1) Ignition timing is not adjustable. | ||
| (1) | Ignition timing is not adjustable. |
IGNITION TIMING (DEGREES BTDC @ RPM)
CONTROLLED IDLE SPEED CHECK
Note. DO NOT attempt to adjust idle mixture and idle speed. Both are controlled by Electronic Control Module (ECM). Incorrect idle speeds are normally caused by dirty throttle plate or vacuum leaks. Ensure all vacuum components are functioning properly.
Note. Controlled idle speed and IAC count can be checked using scan tester. See CONTROLLED IDLE SPEED & IAC COUNT .
- Ensure no trouble code(s) are present, IAC system is okay, and ignition timing is correct. Block drive wheels. Apply parking brake. Connect Tech 1 scan tester to Data Link Connector (DLC). Put scan tester into OPEN mode.
- Start engine and bring to normal operating temperature. Check for correct state of Park/Neutral switch on scan tester. Check if idle speed and IAC valve pintle position (counts) are as specified. See «CONTROLLED IDLE SPEED & IAC COUNT»(/chevrolet/caprice-impala-ss/1995-1996/remont/adjustments/#engine-controls-adjustments-43l) .
- If idle speed is not within specification, refer to «TESTS W/O CODES - GASOLINE»(ref-20057) article in this section.
| Application | Idle RPM | (1) IAC Counts | |||
|---|---|---|---|---|---|
| CPI | |||||
| "L" Series (A/T) (2) | 625 | 15-50 | |||
| "M", "S" & "T" Series (A/T) (2) | 550 | 5-40 | |||
| TBI | |||||
| "C" & "K" Series | |||||
| Auto. Trans. (2) (4) | 537 | 5-30 | |||
| Auto. Trans. (2) (4) | 650 | 20-35 | |||
| Man. Trans. (3) | 550 | 2-20 | |||
| "G" Series | |||||
| Auto. Trans. (2) | 538 | 5-30 | |||
| Man. Trans. (3) | 650 | 5-30 | |||
| "L" Series | |||||
| Auto. Trans. (2) | 625 | 5-50 | |||
| Man. Trans. (3) | 700 | 3-30 | |||
| "M" Series (A/T) (2) | 538 | 5-30 | |||
| "P" Series | |||||
| Auto. Trans. (2) | 650 | 5-30 | |||
| Man. Trans. (2) | 700 | 5-30 | |||
| "S" & "T" Series | |||||
| Auto. Trans. (2) | 650 | 5-30 | |||
| Manual Trans. | |||||
| Pickup | 725 | 3-30 | |||
| Utility | 700 | 5-30 | |||
| (1) Add 2 counts for engines with less than 500 miles. On 4.3L engines, add 2 counts for every 1000 ft. above sea level. (2) Automatic transmission in Drive. (3) Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. (4) Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. | |||||
| (1) | Add 2 counts for engines with less than 500 miles. On 4.3L engines, add 2 counts for every 1000 ft. above sea level. |
| (2) | Automatic transmission in Drive. |
| (3) | Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. |
| (4) | Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. |
CONTROLLED IDLE SPEED & IAC COUNT
THROTTLE POSITION (TP) SENSOR
TP sensor output voltage should be .85 volt or less at idle (closed throttle).
See also:
• IGNITION TIMING