Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
I have an 05 TB with 82K. Scaned it today cause I have been having misfires at idle and could feel it. Now when I drive it is sluggish until over 4k rpm. You can feel the motor be sluggish and then drives like normal, then sluggish again. I know the P0410 code is my secondary injection valve and have ordered a new one since mine is stuck closed. But the P0300 random misfire is killing me. I have bosch platnium plugs and someone said that they are to hot for the I6. I will change those to AC Delco's. But does anyone else have any ideas. :(
 

·
Registered
2007 chevy trailblazer_ls
Joined
·
1,240 Posts
Hope this helps you. If it doesn't, I can email you some bullitens regarding P0300.



DTC P0300
System Description
The powertrain control module (PCM) uses information from the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If the PCM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 will set.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0300 Engine Misfire Detected

Conditions for Running the DTC
• DTC P0013, P0014, P0016, P0106, P0107, P0108, P0117, P0118, P0120, P0125, P0128, P0218, P0220, P0315, P0336, P0340, P0341, P0502, P0503, P2125, P2135 are not set.

• The engine is running.

• The ignition voltage is between 10-18 volts.

• The engine coolant temperature (ECT) is between -7 and +130°C (+19 and +266°F).

• The throttle angle is steady.

• The A/C compressor clutch is not changing state.

• The exhaust gas recirculation (EGR) flow test is inactive.

• The fuel level is above 10 percent.

• The fuel cut-off or decel fuel cut-off (DFCO) mode is not active.

• The PCM is not receiving a rough road signal.

• DTC P0300 runs continuously when the above conditions are met.

Conditions for Setting the DTC
The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.

Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
Important: You must perform the CKP system variation learn procedure before proceeding with this diagnostic table. Refer to Crankshaft Position System Variation Learn .

• Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration:

- Thickness variation of the brake rotors--Refer to Symptoms - Hydraulic Brakes in Hydraulic Brakes.

- The drive shaft not balanced--Refer to Vibration Analysis - Driveline in Vibration Diagnosis and Correction.

- Worn or damaged accessory drive belt--Refer to Symptoms - Engine Mechanical in Engine Mechanical.

• There may be more or less cylinders actually misfiring than indicated by the scan tool.

Test Description
The number below refers to the step number on the diagnostic table.

If the actual CKP variation values are not within the learned values, the misfire counters may increment.

Step
Action
Values
Yes
No

1
Did you perform the Diagnostic System Check - Vehicle?
--
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
Start the engine.
Allow the engine to idle or operate within the conditions listed in the Freeze Frame/Failure Records.
Monitor all of the Misfire counters with the scan tool.
Are any of the Misfire current counters incrementing?
--
Go to Step 3
Go to Diagnostic Aids

3
Are any other DTCs set?
--
Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information
Go to Step 4

4
Can any abnormal engine noise be heard?
--
Go to Symptoms - Engine Mechanical
Go to Step 5

5
Inspect the following components:

• The vacuum hoses and seals for splits, restrictions, and improper connections--Refer to Engine Controls Schematics .

• The throttle body and intake manifold for vacuum leaks

• The crankcase ventilation system for vacuum leaks--Refer to Crankcase Ventilation System Inspection/Description in Engine Mechanical.

• The powertrain control module (PCM) grounds for corrosion and loose connections--Refer to Ground Distribution Schematics in Wiring Systems.

• The exhaust system for restrictions--Refer to Restricted Exhaust in Engine Exhaust.

• The fuel for contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Did you find and correct the condition?
--
Go to Step 13
Go to Step 6

6
Remove the spark plugs from the cylinders that indicated a misfire. Refer to Spark Plug Replacement .
Inspect the spark plug. Refer to Spark Plug Inspection .
Do the spark plugs appear to be OK?
--
Go to Step 10
Go to Step 7

7
Are the sparks plug oil or coolant fouled?
--
Go to Symptoms - Engine Mechanical
Go to Step 8

8
Are the spark plugs gas fouled?
--
Go to Step 11
Go to Step 9

9
Did the spark plugs show any signs of being cracked, worn, or improperly gapped?
--
Go to Step 12
Go to Step 10

10
Perform the fuel injector coil test. Refer to Fuel Injector Solenoid Coil Test .

Did you find and correct the condition?
--
Go to Step 13
Go to Symptoms - Engine Mechanical

11
Perform the fuel system diagnosis. Refer to Fuel System Diagnosis .

Did you find and correct the condition?
--
Go to Step 13
Go to Symptoms - Engine Mechanical

12
Replace or gap the spark plugs. Refer to Spark Plug Replacement .

Did you complete the action?
--
Go to Step 13
--

13
Was the customer concern the malfunction indicator lamp (MIL) flashing?
--
Go to Step 14
Go to Step 15

14
Operate the vehicle at the specified value for 4 minutes.
Operate the vehicle within the Conditions for Running the DTC P0420, as specified in the supporting text. Refer to DTC P0420 .
Does DTC P0420 run and pass?
2,500 RPM
Go to Step 15
Go to DTC P0420

15
Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
--
Go to Step 2
Go to Step 16

16
Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information
System OK
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #4 ·
:thxWell, I have figured it out!:bonk: I changed the spark plugs and found out it had Bosch Platniums+2 i it and was told they were too hot of a plug and they melt down. Low and behold, that's what had happened to mine. So I put AC Delco Irdium plugs and everything is gone. i have my power back and no more random misfire. Thanks all for the help:woot:
 
1 - 5 of 5 Posts
Top