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.
IGNITION TIMING
- Set parking brake. Block drive wheels. Place transmission in Neutral or Park. Warm engine to operating temperature. Turn A/C off (if equipped). Ensure Malfunction Indicator Light (MIL) is not on.
- Disconnect Electronic Spark Timing (EST) by-pass connector (Tan/Black wire) which is located near distributor or in cab behind glove box. DO NOT disconnect 4-wire connector at distributor.
- Connect timing light to No. 1 spark plug wire. Check timing and adjust if necessary. See «IGNITION TIMING»(/gmc/suburban/i-1992-1999/remont/adjustments/#engine-controls-adjustments-57l) . Reconnect EST by-pass connector. Clear DTC.
| Application | Man. Trans. | Auto. Trans. |
|---|---|---|
| 5.7L (VIN K) | 0 @ Idle | 0 @ Idle |
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»(/gmc/suburban/i-1992-1999/remont/adjustments/#engine-controls-adjustments-57l) .
- If idle speed is not within specification, refer to «TESTS W/O CODES - GASOLINE»(/gmc/suburban/i-1992-1999/remont/testing-diagnostics/#engine-controls-tests-wo-codes-gasoline) article in this section.
| Application | Idle RPM | (1) IAC Counts | |
|---|---|---|---|
| Under 8500 GVW | |||
| Auto. Trans. (2) | 550 | 5-30 | |
| Man. Trans. (3) | 700 | 5-30 | |
| Over 8500 GVW | |||
| Auto. Trans. (2) | 550 | 5-30 | |
| Man. Trans. (3) | 600 | 5-30 | |
| (1) Add 2 counts for engines with less than 500 miles. On V8 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. | |||
| (1) | Add 2 counts for engines with less than 500 miles. On V8 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. |
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:
• TESTS W/O CODES - GASOLINE
• IGNITION TIMING