Lack of Power/Sluggish/Spongy/Stumble

Definition: Engine delivers less than expected power, little or no increase in speed when accelerator pedal is pushed down part way.

^ Perform "Diagnostic Circuit Check - Calif."

^ Perform "System Performance Check - Calif".

^ Visual (Physical) Check

- Vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label.

- Ignition wires for cracking, harness, and proper connections, at both the distributor cap and spark plugs.

- Wiring for proper connections, pinches and cuts.

^ Compare customer's vehicle to similar unit. Make sure the customer's vehicle has an actual problem. Was the customer's old vehicle much more powerful?

^ Make sure hot air tube is connected to air cleaner.

^ Remove air cleaner and check air filters for dirt, or for being plugged. Replace as necessary.

^ Check for proper operation of THERMAC.

^ Check for full throttle valve opening in carburetor by depressing accelerator pedal to floor.

^ Check for proper operation of carburetor air valve (if equipped).

^ Check carburetor float level using external float gage.

^ Check ignition timing. See Vehicle Emission Control Information Label.

^ Check transmission for proper downshift and TCC operation.
^ Check EGR operation. See Chart C-7.


^ Check EST operation. If ALCL tool is available, check for excessive retard. Excessive retard may be caused by carbon build-up in cylinders which can be removed with "Top Engine Cleaner."


^ Check vacuum sensor output as applicable. see C-1E.


^ Check EFE Electric Heater operation. See Chart C-9.


^ Remove spark plugs. Check for cracks, wear, improper gap, burned electrodes, heavy deposits. Repair or replace as necessary.

^ Check for an exhaust system restriction:


1. With engine at normal operating temperature, connect a vacuum gage to any convenient vacuum port on intake manifold.

2. Run engine at 1000 RPM and record vacuum reading.

3. Increase RPM slowly to 2500 RPM. Note vacuum reading at steady 2500 RPM.

4. If vacuum at steady 2500 RPM is more than 3" lower than at 1000 RPM, exhaust system should be inspected for restrictions, see Restricted Exhaust System Check.

^ Check engine valve timing and compression.

^ Check engine for proper or worn camshaft.

^ Poor or contaminated fuel. Suggest owner try different brand.