A malfunction in the EFC system may result in engine surge, hesitation, rough idle and/or poor fuel economy. Before making any tests, check all vacuum and electrical wiring for proper routing and connections, and check for exhaust and intake manifold leaks.
Check for spark at spark plug wire, for fuel in carburetor, for fouled spark plugs, and for improper engine timing. Using an ohmmeter, check resistance of ignition coil-to-distributor secondary wire. Resistance should be 250-600 ohms per inch (3000-7200 ohms per foot). Replace wire if not to specifications.
Connect ohmmeter leads to ignition coil positive and negative terminals. Coil primary resistance should be 1.6-1.8 ohms. Remove coil secondary wire and connect ohmmeter leads to the coil negative and secondary terminals. Coil secondary resistance should be 9400-22,700 ohms. If either ohmmeter reading is not to specification, replace ignition coil.
If tests in steps 2) and 3) prove satisfactory, system testing may begin.

NOTE: The Spark Control Computer controls ignition timing as well as air/fuel mixture. Before testing EFC system, perform SPARK CONTROL TEST.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Preliminary Tests