Diagnosis & Repair

Check for misfire during engine warm up only. Check for use of improper fuel. Check proper connector connections. Also check for proper vacuum hose connection. Repair as necessary. If connector connections and vacuum hoses are okay, go to next step.
Check spark plugs and check for spark. See BASIC TESTING article. Repair as necessary. If spark plugs are okay and spark exists, go to next step.

Turn ignition on. Backprobing, measure voltage between ground and injector terminals at ECM E16 or E15 connector. See Figure. See IDENTIFYING INJECTOR TERMINALS table. If using oscilloscope see illustration for correct waveform pattern. See Fig 1. If measured voltage is 9-14 volts for each circuit, go to step 5). If voltage is not 9-14 volts, go to next step.

IDENTIFYING INJECTOR TERMINALS

Injector No.

Terminal No.

Wire Color

5 ⁽¹⁾

Yellow

6 ⁽¹⁾

Red

1 ⁽²⁾

Black

2 ⁽²⁾

Black/Red

3 ⁽²⁾

White/Blue

4 ⁽²⁾

Red/White

5 ⁽²⁾

Blue/Red

6 ⁽²⁾

Green

⁽¹⁾	Terminals are located in ECM E16 connector. See Figure.

⁽²⁾	Terminals are located in ECM E15 connector. See Figure.

Disconnect injector of misfiring cylinder. Using ohmmeter, measure resistance between injector terminals. With injector temperature at 68°F (20°C), resistance should be 13.4-14.2 ohms. If resistance is as specified, check for open or short circuit in wiring harness between ECM E16 or E15 connector and injector. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article. Repair as necessary. If resistance is not as specified, replace suspect injector.
Check fuel pressure. See BASIC TESTING article. Repair as necessary. If fuel pressure is okay, check fuel injectors. See SYSTEM/COMPONENT TESTS article. Replace as necessary.
If all injectors are okay, check MAF sensor or ECT sensor. See SYSTEM/COMPONENT TESTS article. Replace as necessary. If MAF sensor and ECT sensor are okay, check engine compression, valve clearance and valve timing. Repair as necessary.

Fig 1: Fuel Injectors Signal Waveform