ENGINE MECHANICAL
Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.
Tribute 2.0L
- Ensure engine is cold. Remove valve cover. Using feeler gauge, measure valve clearance between base of camshaft lobe and valve tappet. Record measurement and location of all valve tappets. If any tappets are not within specification, go to next step. See «VALVE CLEARANCE SPECIFICATIONS»(ref-134956-S05677517902002022100000) table.
- Remove timing belt and appropriate camshaft for valves requiring adjustment. See appropriate article in ENGINES. Remove appropriate tappet and measure thickness of tappet. Select tappet by adding measured clearance plus base tappet thickness minus most desirable clearance. Lubricate tappets with SAE 5W-30 oil and reinstall camshafts. Ensure valve clearances are as specified. See «VALVE CLEARANCE SPECIFICATIONS»(ref-134956-S05677517902002022100000) table. To complete repair, reverse removal procedure. Install NEW valve cover gasket and timing belt. NOTE: Do not reuse timing belt, install NEW timing belt.
CRANKSHAFT POSITION SENSOR
Note. On all models except Miata, Crankshaft Position (CKP) sensor is not adjustable. If clearance is not as specified, replace CKP sensor or crankshaft pulley.
MIATA
Loosen CKP sensor bolt. Using feeler gauge, adjust air gap between sensor and crankshaft sensor plate projections to.020-0.59" (0.5-1.5 mm). (Scheme 15) Tighten CKP sensor bolt. If clearance is still not within specification, replace CKP sensor or sensor plate behind crankshaft pulley.
Scheme 15
IGNITION TIMING
Note. Before adjusting or inspecting ignition timing, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (M/T) or Park (A/T). Wait for cooling fan to stop. Ensure idle speed is correct. See IDLE SPEED under IDLE SPEED & MIXTURE.
Note. New Generation Star (NGS) scan tool is used to perform following procedures.
626
- Connect NGS scan tool to DLC-2 located under left side of instrument panel, left of steering column. (Scheme 16)and (Scheme 19). Ensure idle speed is correct. See «IDLE SPEED & MIXTURE»(ref-134956-S19728863052002022100000).
- Connect timing light to high-tension lead No. 1 and check timing. (Scheme 20) See «IGNITION TIMING SPECIFICATIONS»(ref-134956-S09065139032002022100000) table. If ignition timing is not within specification, check CMP, CKP, TP and ECT sensors, neutral, clutch and transmission range switches. See «SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE, PROTEGE5 & 626»(ref-134969) article. If all sensors and switches are okay, replace PCM.
| Application | With Ten Terminal Grounded | Without Ten Terminal Grounded | ||
|---|---|---|---|---|
| Miata | 9-11 @ 750-850 | 6-18 @ 750-850 | ||
| Millenia | ||||
| 2.3L | 6-8 @ 600-700 | 5-15 @ 600-700 | ||
| 2.5L | 9-11 @ 600-700 | 6-18 @ 600-700 | ||
| MPV | 4-16 @ 700-800 S | N/A | ||
| Protege & Protege5 | 9-11 @ 650-750 | 6-18 @ 650-750 | ||
| 626 | ||||
| 2.0L | ||||
| A/T | N/A | 6-18 @ 500-800) | ||
| M/T | N/A | 6-18 @ 550-850 | ||
| 2.5L | N/A | 4-16 @ 550-750 | ||
IGNITION TIMING SPECIFICATIONS (DEGREES BTDC @ RPM)
Scheme 16
Scheme 17
Scheme 18
Scheme 19
Scheme 20
IDLE SPEED & MIXTURE
Note. Idle mixture is not adjustable. If idle mixture is incorrect, see appropriate SELF-DIAGNOSTICS article.
Note. New Generation Star (NGS) scan tool is used to perform following procedures.
COLD (FAST) IDLE SPEED
Note. Fast idle speed is computer controlled and is not adjustable.
IDLE SPEED
Note. Before adjusting idle speed, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (M/T) or Park (A/T). Ensure battery is fully charged. Wait for cooling fan to stop. DO NOT adjust idle using Throttle Adjusting Screw (TAS). TAS is preset and if adjusted, will adversely affect engine performance.
B-Series Truck, MPV & Tribute
| CAUTION | Throttle body bore and plate area have a special coating and should not be cleaned. |
Idle speed is controlled by Powertrain Control Module (PCM) and is not adjustable. If engine idle concerns are present, check for contaminated fuel, vacuum leaks and incorrect ignition timing. Ensure throttle bore, EGR system and PCV system are clean. If these are okay, check PCM for Diagnostic Trouble Codes (DTCs). See appropriate SELF-DIAGNOSTICS article. If no DTCs are present, go to TROUBLE SHOOTING - NO CODES article.
Connect NGS scan tool to DLC-2 located under left side of instrument panel
- B-series trucks - Under steering column
- MPV and Tribute - Left of steering column
Miata, Millenia, Protege & Protege5
- Connect NGS scan tool to DLC-2 located under left side of instrument panel: Miata, Protege and Protege5 - Left of steering column Millenia - Right of steering column (Scheme 16)or (Scheme 17). Connect a jumper wire between terminals TEN and GND at DLC-1 in engine compartment. (Scheme 18)
- Start engine and allow it to idle. Turn off all electrical loads. Using NGS scan tool, select PID/DATA MONITOR AND RECORD and monitor RPM. If idle speed is not within specification, rotate Air Adjusting Screw (AAS) on throttle body. (Scheme 21)- (Scheme 24). See «IDLE SPEED SPECIFICATIONS»(ref-134956-S09893003642002022100000) table.
- Connect NGS scan tool to DLC-2 located under left side of instrument panel, right of steering column. (Scheme 16) Start engine and allow it to idle. Using NGS scan tool, select PID/DATA MONITOR AND RECORD, press TRIGGER.
- Select RPM and press TRIGGER. Verify idle speed. See «IDLE SPEED SPECIFICATIONS»(ref-134956-S09893003642002022100000) table. If idle speed is not within specification, select HDLMP under PID/DATA MONITOR AND RECORD. Press TRIGGER. Verify HDLMP status changes from OFF to ON when operating headlight switch (PASSING position). If HDLMP status changes, go to next step. If HDLMP status does not change, see appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.
- Connect inductive-type tachometer. Select DIAGNOSTIC TEST MODES. Press TRIGGER. Select KOER ON-DEMAND SELF-TEST. Press TRIGGER. After scan tool displays FOR EXAMPLE BOO, PSP AND TCS, operate headlight switch to (PASSING position) 3 times (for 2 seconds each time). Ensure idle speed is fixed. Within 2 minutes, adjust idle speed to specification by turning Air Adjusting Screw (AAS). (Scheme 23)and (Scheme 24). See «IDLE SPEED SPECIFICATIONS»(ref-134956-S09893003642002022100000) table.
| Application | Specification | ||
|---|---|---|---|
| B2300 | (1) | ||
| B3000 | 760-800 | ||
| B4000 | 760-800 | ||
| Miata (2) | 750-850 | ||
| Millenia (2) | 600-700 | ||
| MPV | 700-800 | ||
| Protege & Protege5 (2) | 650-750 | ||
| Tribute | |||
| 2.0L | 800-900 | ||
| 3.0L | 730-750 | ||
| 626 | |||
| 2.0L | |||
| A/T | 500-800 | ||
| M/T | 550-850 | ||
| 2.5L | 550-750 | ||
| (1) Information is not available from manufacturer. (2) With fused jumper wire connected between ground and TEN terminal at DLC-1. | |||
| (1) | Information is not available from manufacturer. |
| (2) | With fused jumper wire connected between ground and TEN terminal at DLC-1. |
IDLE SPEED SPECIFICATIONS
Scheme 21
Scheme 22
Scheme 23
Scheme 24
THROTTLE POSITION SENSOR
Note. DO NOT adjust Throttle Adjusting Screw (TAS). Throttle adjusting screw is preset and if adjusted, will adversely affect engine performance.
Note. New Generation Star (NGS) scan tool is used to perform following procedures.
MILLENIA 2.3L
Note. Throttle position switch is an integral part of TP sensor. After performing this procedure, ensure TP sensor is within specification. If not within specification, replace TP sensor. See INSPECTION & ADJUSTMENT USING NGS SCAN TOOL (MIATA, MILLENIA, MPV & 626) or INSPECTION USING DVOM under THROTTLE POSITION SENSOR VOLTAGE under THROTTLE POSITION SENSOR.