Standard Emissions

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.

PRELIMINARY CHECKS
Perform the "Visual and Physical Checks" as described in Preliminary Checks. Testing and Inspection

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

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

2. If there is an RPM drop, on all cylinders, (equal to within 50 RPM), go to Rough, Unstable Or Incorrect Idle, Stalling symptom. Rough, Unstable, or Incorrect Idle, Stalling
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 or equivalent. If no spark, refer to Chart A1-3 Engine Cranks But Will Not Run. Chart A1-3 Engine Cranks But Will Not Run

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 ignition and connections.

NOTICE: If the previous checks did not find the malfunction:
^ 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 A1-7B Fuel System Pressure Check for fuel pressure check procedure. Chart A1-7B Fuel System Pressure Check

For additional checks, refer to On-Board Diagnostic System Check. Testing and Inspection

CHECK: For contaminated fuel or restricted fuel filter.

ENGINE MECHANICAL
CHECK: For proper valve lash adjustment.
CHECK: Low compression. Perform compression check.
CHECK: Intake and exhaust manifold passages for casting flash.