Cuts Out/Misses

CUTS OUT, MISSES
Definition: 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

IMPORTANT PRELIMINARY CHECKS
Before using this section you should have performed the "On-Board Diagnostic System Check" - Powertrain/On-Board Diagnostic System Check and determined that:
1. The control module and MIL (Service Engine Soon) are operating correctly.
2. There are no diagnostic trouble codes stored, or there is a diagnostic code but no MIL (Service Engine Soon).
^ Several of the following symptom procedures call for a careful visual/physical check. The importance of visual/physical checks cannot be over stressed. because they can lead to correcting a problem without further checks and can save valuable time.

VISUAL / PHYSICAL CHECK
This check should include:
^ Control module grounds for being clean, tight, and in their proper location.
^ Vacuum hoses for splits, kinks and proper connections, as shown on "Vehicle Emission Control Information" label Check thoroughly for any type of leak or restriction.
^ Air leaks at all mounting areas of the intake manifold sealing surfaces.
^ Ignition wires for cracking, hardness, proper routing, or carbon tracking.
^ Wiring for proper connections, pinches, and cuts.
^ The following symptom charts contain groups of possible causes for each symptom and cover several engines. These procedures are not necessarily meant to be done in consecutive order. If Tech 1 scan tool readings do not indicate the problems, then proceed in a logical order, easiest to check or most likely cause first. To determine if a particular system or component is used on a specific vehicle, refer to the "Electronic/Powertrain Control Module (ECM/PCM)" Wiring Diagrams for application. Electronic/Powertrain Control Module (ECM/PCM)

^ If there is spray from only one injector on a TBI system, then, there may he a malfunctioning injector assembly, or in the signal to the injector assembly. The malfunction can be isolated, by switching the injector connectors. If the problem remains with the original injector, after switching the connector, the injector is defective. Replace the injector. If the problem moves with the injector connector, the problem is an improper signal in the injector circuits. Refer to "CHART A-3".

IGNITION SYSTEM
^ CHECK: For cylinder miss by:
1. Start engine, allow engine to stabilize then disconnect IAC motor. Remove one spark plug wire at a time, using insulated pliers.

NOTICE: Do not perform this test for more than 2 minutes, as this may cause damage to the catalytic converter.

2. If there is a RPM drop, on all cylinders, (equal to within 50 RPM), go to "Rough, Unstable or Incorrect Idle, Stalling" symptom. Reconnect IAC motor with ignition "Off".
3. If there is no RPM drop on one or more cylinders, or excessive variation in drop, check for spark, on the suspected cylinder(s) with J 26792 (ST-125) Spark Tester or equivalent.
4. If no spark, refer to Ignition System Check. Ignition System Check
5. If there is spark, remove spark plug(s) in these cylinders and check for;
- Insulation cracks.
- Wear
- Improper gap. Burned electrodes.
- Heavy deposits.

^ CHECK: Spark plug wire resistance (should not exceed 30,000 ohms), also, check rotor and distributor cap.
^ CHECK: If the previous checks did not find the problem:
- Visually inspect ignition system for moisture, dust, cracks, burns, etc. With engine running, spray plug wires with fine water mist to check for shorts

FUEL SYSTEM
^ CHECK: Fuel pressure. Refer to "CHART A-6". Related Tests, Information and Procedures
^ CHECK: For contaminated fuel or restricted fuel filter.

ENGINE MECHANICAL
^ CHECK: For proper valve timing, low compression, bent pushrods, worn rocker arms, broken or weak valve springs, worn camshaft lobes.
^ CHECK: Intake and exhaust manifold passages for casting flash.