Checks 
 | Action 
 | 
Definition: The
fuel ignites in the intake manifold, or in the exhaust system, making  a loud
  popping    noise. 
 | 
Preliminary Check 
 | Refer to 
Symptoms - Engine Controls 
. 
 | 
Ignition System Checks 
 | 
|     •  | Check for crossfire between spark plugs, such as the distributor
cap, spark plug wires, and proper routing of the plug wires. |  
  
 | 
Engine
Mechanical Checks 
 | 
|     •  | Check the engine for the following the items: |  
  
|        -  | Sticking or leaking valves |  
  
|     •  | Check the exhaust gas recirculation (EGR) operation for being
open all the time. |  
  
|     •  | Check the intake and exhaust system for fresh air entering the
exhaust upstream of the catalytic converter or restrictions. |  
  
 | 
Fuel
System Checks 
 | 
 | 
Additional
Checks 
 | 
|     •  | Check the EGR gasket for a faulty or loose fit. |  
  
|     •  | Check the secondary air injection (AIR) system for proper operation,
if applicable. |  
  
 |