Ccc Tests W/o Codes: Diagnosis Chevrolet RV Cutaway G30

HOW TO USE THIS TROUBLE SHOOTING ARTICLE

The Trouble Shooting section should be used only AFTER the SYSTEM CHECK chart procedures have been performed to verify that

1. On-Vehicle Diagnostics are working.
2. There are no trouble codes stored, or only intermittent ones.
3. Fuel control system is operating properly as verified by Field Service Mode Check.

Verify customer complaint and locate the correct symptom below. Check items indicated under that symptom. These procedures will normally lead to a component system on the vehicle, such as EGR, EST, TCC, etc. These are covered in the Component charts.

The flow charts are located in the TBI CEC TESTING article in this section. If the first flow chart leads you to another flow chart, all the test charts are in the TBI CEC TESTING article. If a flow chart leads you to trouble shooting procedures, that information will be in this article.

Check items indicated under that symptom. These procedures will normally lead to a component system on the vehicle, such as EGR, EST, TCC, etc. These sytems are covered in the component charts.

Several of the following symptom procedures call for a careful visual check. Visual check should be performed CAREFULLY and THOROUGHLY as it can correct a problem without further checks or diagnosis. This check should include

1. Vacuum hoses for splits, kinks and proper connections, as shown on Emission Control Information label.
2. Air leaks at throttle body mounting and intake manifold.
3. Ignition wires for cracking, hardness, proper routing, and carbon tracking.
4. Wiring for proper connections, pinches, and cuts.

Note. If engine cranks but will not run, see CHART A3 - ENGINE CRANKS BUT WON'T RUN chart in the TBI TESTS W/ CODES article in this section.

SYMPTOM DEFINITION

Intermittent problem(s) may or may not turn on "SERVICE ENGINE SOON" light. Code(s) may or may not be stored.

Engine cranks but doesn't start for a long time. Engine eventually runs, or engine starts but immediately dies.

Momentary lack of response as accelerator is depressed. May occur at any vehicle speed. Usually most severe when first trying to make vehicle move. May cause vehicle to stall if severe enough.

As determined by actual road test, fuel economy is significantly lower than expected. Also, fuel economy is much lower than had been previously shown by an earlier road test.

Engine continues to run after ignition is turned off, but runs very rough. If engine runs smoothly, check ignition switch and adjustment.

Fuel ignites in intake manifold, or exhaust manifold, making a loud popping noise.

Engine runs unevenly at idle. If severe enough, vehicle may shake. Engine may display varied idle RPM ("hunting"). Either condition could be severe enough to cause stalling. Engine idles at incorrect speed.

Excessive odors (high concentrations of CO and HC) that are more noticeable when engine is under load and at normal operating temperatures.

Engine power variation under steady throttle or cruise condition. Feels like vehicle speeds up and slows down without changing accelerator pedal position.

Engine delivers less than expected power. Little or no increase in speed when accelerator pedal is depressed part way.

A mild to severe ping, usually worse under acceleration. Engine makes sharp metallic knocks that change with throttle opening.

Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. The exhaust has a steady spitting sound at idle or low speed.