Cuts Out, Misses

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Cuts Out, Misses

Checks	Action
DEFINITION: A surging or jerking that follows engine speed, usually more pronounced as the engine load increases.
Preliminary Checks	Refer to Important Preliminary Checks in Symptoms - Engine Controls .
Fuel System Checks	Test for proper fuel system pressures. Refer to Fuel System Diagnosis . Inspect for proper operation of the CNG fuel injectors. Refer to: Fuel Injector Coil Test Fuel Injector Balance Test with Special Tool Fuel Injector Balance Test with Tech 2 Test the high and low pressure lock-off valves/circuits for proper operation.
Ignition System Checks	IMPORTANT: A higher secondary ignition voltage is required to operate the vehicle on CNG than on gasoline. Check for proper secondary ignition system voltage output using ONLY the J 26792 Spark Tester. Inspect for fouled spark plugs. If fouled spark plugs are indicated the reason for the fouling must be found and corrected. Test for faulty spark plug wires. Test for an open ignition system ground, if equipped.
Engine Mechanical Checks	Test for proper engine operation by checking for the following: Correct engine compression Correct engine valve timing A worn or incorrect camshaft Bent pushrods Worn rocker arms Casting flash in the intake or exhaust manifold passages
Additional Checks	Inspect for electromagnetic interference (EMI) by checking for the following: Monitoring engine speed on the scan tool may indicate EMI is present. A sudden increase in scan tool engine speed while actual engine speed remains constant indicates EMI is present. EMI on the ignition control circuit may cause a missing condition.