2004SSS

iTrader: (25)

why is that? im having a similar problem in my camaro too. its missing at higher rpms when im on it. i do have a bad knock sensor though i need to change it just been lazy. its starting to **** me off though maybe ill get on it tommorrow.

ernie325

No, not yet, believe it or not a back pressure gauge is one tool I don't have. It is on order however. Should have later this week. Stop over when you see the truck up in the air.

2004SSS

iTrader: (25)

well i changed my knock sensors this past weekend( pita) but it solved my mifiring and camaro runs like new again!!

gmforlife

iTrader: (2)

Document ID# 750788
2002 Chevrolet Chevy C Silverado - 2WD


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DTC P0101
Circuit Description
The mass air flow (MAF) sensor is an airflow meter that measures the amount of air that enters the engine. The powertrain control module (PCM) provides the correct fuel delivery for a number of engine speeds and of engine loads using the MAF sensor signal. A small quantity of air that enters the engine indicates deceleration or idle. A large quantity of air that enters the engine indicates an acceleration or a high load condition. The MAF sensor has the following circuits:

• An ignition 1 voltage circuit

• A ground circuit

• A signal circuit

The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency that is based on inlet air flow through the sensor bore. The frequency varies within a range of around 2,000 Hertz at idle to about 10,000 Hertz at maximum engine load. The PCM uses the following sensor inputs in order to calculate a predicted MAF value:

• The manifold absolute pressure (MAP) sensor

• The intake air temperature (IAT) sensor

• The engine coolant temperature (ECT) sensor

• The engine speed

The PCM compares the actual frequency signal from the MAF sensor to the predicted MAF value. This will determine if the signal is stuck because of a lack of variation, or is too low or too high for the operating condition. DTC P0101 sets if the actual frequency signal from the MAF sensor is not within a predetermined range of the calculated MAF value.

Conditions for Running the DTC
• DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0121, P0122, P0123, P1111, P1112, P1120, P1121, P1122, P1220, or P1221 are not set.

• The engine is running.

• The ignition 1 signal is between 11-18 volts.

• The throttle position (TP) sensor angle is less than 95 percent.

• The change in the TP sensor angle is less than 5 percent.

• The manifold absolute pressure (MAP) sensor is more than 17 kPa.

• The change in the MAP sensor is less than 3 kPa.

• The above conditions are met for 1.5 seconds.

Conditions for Setting the DTC
The actual frequency signal from the MAF sensor is not within a predetermined range of the PCM calculated MAF value for more than 0.5 seconds.

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
Inspect for the following conditions:

• A misrouted harness--Inspect the harness of the MAF sensor in order to verify that the harness is not routed too close to the following components:

- The secondary ignition wires or the coils

- Any solenoids

- Any relays

- Any motors

• A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration.

• A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 4-7 g/s at idle to 150 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction.

• The barometric pressure (BARO) that is used in order to predict the MAF value is initially based on the MAP sensor at key ON. When the engine is running, the MAP sensor value is continuously updated at a WOT or near a WOT. A skewed MAP sensor will cause the calculated MAF value to be inaccurate. The value that is shown for the MAP sensor display varies with the altitude. With the ignition ON and with the engine OFF, 103 kPa is the approximate value at the sea level or near the sea level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude.

If you suspect the condition may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Wiring Systems.

If the condition is intermittent, refer to Intermittent Conditions .

Test Description
The numbers below refer to the step numbers on the diagnostic table.

This step will determine if the MAP sensor voltage is within the proper range at idle.

This step will determine if the MAP sensor responds correctly to the change in manifold pressure.

This step will determine if the TP sensor is operating correctly.

This step will determine if any mechanical faults have caused this DTC to set.

Step
Action
Values
Yes
No

Schematic Reference : Engine Controls Schematics

1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls

2
Start the engine.
Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the scan tool display any other DTCs set?
--
Go to Diagnostic Trouble Code (DTC) List
Go to Step 3

3
Observe the Freeze Frame/Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC, or as close to the Freeze Frame/Failure Records data that you observed.
Does the DTC fail this ignition?
--
Go to Step 4
Go to Diagnostic Aids

4
Allow the engine to reach operating temperature.
Observe the MAP sensor voltage with a scan tool .
Is the MAP sensor voltage within the specified range?
0.8-4 V
Go to Step 5
Go to DTC P0106

5
Idle the engine.
Observe the MAP sensor kPa with a scan tool.
Increase the engine speed slowly to 3,000 RPM, and decrease back to idle.
Does the MAP sensor kPa change smoothly and gradually through the specified range of the test?
--
Go to Step 6
Go to DTC P0106

6
Important:: If the vehicle is equipped with a throttle actuator control, continue to the next step.


Turn OFF the ignition.
Turn ON the ignition, with the engine OFF.
Observe the TP sensor angle from a closed throttle to a wide open throttle.
Depress the accelerator pedal completely, and release the accelerator pedal.
Does the scan tool indicate that the TP sensor angle changed smoothly and completely through the specified range of the test?
0-100%
Go to Step 7
Go to DTC P0121

7
Inspect for the following conditions:

• A restricted air intake duct or a collapsed air intake duct

• A dirty air filter element or a deteriorating air filter element

• Any objects that block the air inlet screen of the MAF sensor

• Any unmetered air that enters the engine downstream of the MAF sensor

Did you find and correct the condition?
--
Go to Step 10
Go to Step 8

8
Test for an intermittent and for a bad connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 10
Go to Step 9

9
Replace the MAF/IAT sensor. Refer to Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement .

Did you complete the replacement?
--
Go to Step 10
--

10
Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC.
Does the DTC run and pass?
--
Go to Step 11
Go to Step 2

11
With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK



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Document ID# 750788
2002 Chevrolet Chevy C Silverado - 2WD

gmforlife

iTrader: (2)

hey i just assumed it was a 2wd, and a silverado, couldn't get much from your sig. Hope this helps

gmtechnician

stopped up cats will cause the MAS to set a code because of the backpressure in the system. anyway check you fuel pressure it can cause your engine to miss at high rpms. same as the cats.

gmforlife

iTrader: (2)

DTC P0300
Circuit Description
The powertrain control module (PCM) uses information from the crankshaft position (CKP) sensors and from the camshaft position (CMP) sensor in order to determine if engine misfire is occurring. By monitoring the variations in the crankshaft rotational speed for each cylinder, the PCM is able to detect individual cylinder misfire events. A misfire rate that is high enough can cause damage to the 3-way catalytic converter (TWC). The malfunction indicator lamp (MIL) will flash if TWC damaging conditions are present.

Conditions for Running the DTC
• DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0335, P0336, P0341, P0343, P0502, P0503, P1114, P1115, P1120, P1220, P1221, or P1336 are not set.

• The engine speed is between 375-5,001 RPM for an automatic transmission.

• The engine speed is between 450-5,001 RPM for a manual transmission.

• The ignition voltage is between 10-18 volts.

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

• The fuel level is more than 10 percent.

• The throttle position (TP) sensor angle is steady within 1 percent.

• The antilock brake system (ABS) and the traction control system are not active.

• The transmission is not changing gears.

• The secondary air injection (AIR) diagnostic test is not in progress (RPO NC1 only).

• The A/C clutch is not changing states.

• The PCM is not in fuel shut-off or decel fuel cut-off (DFCO) mode.

• The ABS signal is not exceeding rough road thresholds.

Conditions for Setting the DTC
• The PCM determines that an emission type misfire is present.

• The PCM determines that a catalyst damaging misfire is present.

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: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Verify that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.


• Running the vehicle out of fuel causes sufficient misfire to set DTC P0300. A vehicle that is out of fuel may have fuel level DTCs also set.

• A restricted fuel filter can cause sufficient misfire to set DTC P0300. Refer to Fuel System Diagnosis .

• Excessive vibration from sources other than the engine can cause a misfire DTC. The following are possible sources of vibration:

- Variable thickness brake rotor

- Drive shaft not balanced

- Certain rough road conditions

• Observe, if more then one cylinder is misfiring, the scan tool may only display one cylinder misfiring. This will not be apparent until the repair is completed. Also, if an ignition coil ground circuit is open for one side of the engine, the scan tool may only display 2 or 3 cylinders misfiring. Inspect the ground circuit for the ignition coil on the cylinder bank of the engine that has more then one cylinder misfiring.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

Wetting down the secondary ignition system with water from a spray bottle may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.

If the Misfire Current counters are incrementing and there is no apparent misfire, an erratic CKP sensor signal could be the cause. Perform the diagnostic table for DTC P0335 first if this condition is suspected.

If a misfire is present and you suspect a fuel control problem, force the fuel system into Open Loop using the scan tool and allow the engine to run for a few minutes. If this eliminates the misfire, refer to any fuel control related DTCs which are set. If no other DTCs are set, refer to the Engine Scan Tool Data List.

A misfire may not be apparent at idle. The misfire may only occur above idle under a load. Road test the vehicle and monitor the misfire current counters.

If more than one cylinder is misfiring, the misfire current counters may only increment for one cylinder. Example: Cylinders 1 and 8 are both misfiring, yet only cylinder 8 increments on the misfire current counter.

If one of the injector fuses is open, only two or three misfire current counters may increment for the corresponding side of the engine.

The cylinder with the more significant misfire may cause another cylinder counter to increment only by a small amount.

If the engine misfire moves with the spark plug, this is good indication that you should replace the spark plug.

An engine mechanical problem can cause a spark plug to gas foul. Inspect for loose rockers, collapsed lifters, or worn camshaft lobes.

If the customer concern is the MIL flashing, this indicates that a Catalyst Misfire has occurred. Drive the vehicle in the conditions to run the catalyst diagnostic.

ernie325

Turned out to be the bank 2 cat. Running great now