Detonation/Spark Knock Symptom
Step
| Action
| Value(s)
| Yes
| No
|
DEFINITION: A mild to severe ping
that is usually worse under acceleration. The engine makes sharp metallic
knocks that change with the throttle opening.
|
1
| Did you
perform the On-Board Diagnostic (OBD) System Check?
| --
|
Go to Step 2
| Go to the
Powertrain On Board Diagnostic (OBD) System Check
|
2
|
- Perform a bulletin search.
- If a bulletin that addresses the symptom is present, correct the
condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
| --
|
Go to Step 14
|
Go to Step
3
|
3
| Did you perform a visual/physical check?
| --
|
Go to Step 4
| Go to
Symptoms
for the Visual /Physical Check
|
4
| If the scan
tool readings are normal, refer to
Engine Scan Tool Data List
, and there are no engine mechanical faults,
fill the fuel tank with a known quality gasoline that has a minimum
octane rating of 91 and re-evaluate the vehicle performance.
Is a detonation present?
| --
|
Go to Step
5
|
Go to Step
14
|
5
|
- Check the transmission range switch circuits. Use a scan tool,
ensuring that the scan tool indicates that the vehicle is in Drive with the
gear selector in Drive or Overdrive.
- If a problem is present, diagnose and repair the transmission
range switch as necessary. Refer to
DTC P0705 Trans Range Switch Circuit
.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
6
|
6
|
- Check the TCC operation. Refer to
Torque Converter Diagnosis
.
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
7
|
7
|
- Check for any obvious overheating problems:
• | Restricted air flow to radiator, or restricted water flow through
radiator |
• | Inoperative electric cooling fans |
• | Correct coolant solution should be a 50/50 mix of approved antifreeze/coolant
and water. Refer to Engine Cooling.
|
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
8
|
8
|
- Check the fuel pressure. Refer to
Fuel System Diagnosis
.
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
9
|
9
|
- Check the items that can cause the engine to run lean (Long Term
Fuel Trim significantly in the positive range).
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
10
|
10
|
- Check the spark plugs for the proper heat range. Refer to General Information.
- Replace any incorrect spark plugs that may have been installed,
if necessary.
Did any spark plugs require a replacement?
| --
|
Go to Step 14.
|
Go to Step
11
|
11
|
- Remove any excessive carbon buildup with a top engine cleaner.
Refer to the instructions on top of the engine cleaner can.
- Re-evaluate the vehicle performance.
Is a detonation still present?
| --
|
Go to Step
12
|
Go to Step
14
|
12
|
- Check for the following Engine Mechanical problems (Refer to Engine Mechanical
):
• | A hydraulic valve lifter problem |
• | Leaking cylinder head gaskets |
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
13
|
13
|
- Review all of the diagnostic procedures within this table.
- If all of the procedures have been completed and no malfunctions
have been found, review/inspect the following items:
• | All of the electrical connections within a suspected circuit and/or
system. |
- If a problem is present, repair as necessary.
Was a problem found?
| --
|
Go to Step
14
|
Go to Step
3
|
14
| Operate the vehicle under the same conditions (as closely
as possible) as when the original symptom occurred.
Is the original symptom still present?
| --
|
Go to Step 3
|
Go to Step
15
|
15
| Are any other driveability symptoms still present?
| --
| Go to
Symptoms
.
| System OK
|