Chart 9
Spark Knock
| SYSTEM/COMPONENT | REFERENCE ( PINPOINT TEST - CNG, FLEX-FUEL & GASOLINE ) unless noted |
|---|---|
| Verify engine operates at normal temperature | Visual (refer to STEP 2: NO DTC(S) PRESENT SYMPTOM CHART INDEX or the appropriate ENGINE COOLING article, to diagnose any cooling system concerns that are present). |
| Verify correct coolant level and coolant concentration | Refer to the appropriate ENGINE COOLING article for proper fill concentrations and fill procedures. |
| Mass Air Flow (MAF) Sensor | GO to C: Mass Air Flow Sensor STEP DC25. |
| Base Engine | Engine System - Refer to the appropriate ENGINE article. |
| Fuel Delivery System | Natural Gas Applications: GO to B: Natural Gas Fuel Delivery System STEP HB1. All Others: GO to C: Fuel Delivery System STEP HC1. |
| Secondary Ignition System | For vehicles equipped with a coil pack ignition system, GO to PINPOINT TEST JC
. For all others, GO to PINPOINT TEST JB . |
| PCV System | GO to G: Positive Crankcase Ventilation (PCV) System STEP HG1. |
| Engine Oil Quality | Visual |
| Additional Testing | GO to Z: Intermittent STEP Z1. |