Have replaced the throttle position sensor, MAP sensor, cam shsft position sensor, crsnk shaft position sensor, stopped two vfacuum leaks, and clesned the throttle body and still getting codes PO108, and PO300. Any hlp would be greatly appreciated
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Totally worn out trying to repair this jeeep Code PO108 and PO300
- Thread starter lwlambert
- Start date
devildodge
Well-known member
Have you tested your coil packs/rotor and coil, plug wires, and checked your spark plugs?
Have you checked for any issues with the wires to each sensor?
Also sometimes O2 sensors can make other sensors show bad when they are not working properly.
Do you have a scan tool? If not go to harbor freight and get one that reads live data, best money I ever spent
Have you checked for any issues with the wires to each sensor?
Also sometimes O2 sensors can make other sensors show bad when they are not working properly.
Do you have a scan tool? If not go to harbor freight and get one that reads live data, best money I ever spent
P0108 Trouble code definition
Manifold Air Pressure (MAP) Barometric Pressure Sensor Circuit High Voltage Input Problem
What the P0108 code means
P0108 is the code for a problem with the MAP electrical circuit sensor having too high voltage input to the Engine Control Unit (ECU). This means that the voltage input to the ECU is too high and that it is not in the correct range for proper engine operation to work with inputs from the Mass Air Flow Sensor (MAF) and Throttle Position Switch (TPS).
What causes the P0108 code?
The MAP circuit input to the ECU is too high problem may have several causes:
P0108 code will be generally preceded by the Check Engine Light coming on the dashboard instrument display. The vehicle will most often not run well, idle poorly, accelerate erratically, have excessive fuel consumption, or backfire because the MAP sensor and throttle position sensor are not operating together.
How does a mechanic diagnose the P0108 code?
P0108 is diagnosed with an OBD-II scanner. A qualified technician should then reset the OBD-II fault codes and road test the vehicle to see if the code comes back. He can observe this by watching live streaming on his scanner while driving. If the code comes back, then the mechanic will need to do a voltage test with the key turned on, using a multimeter, and verifying that there is 5 volts input to the MAP sensor and a minimum of .5 to 1 volt with throttle closed.
With the engine running at idle, it should have minimum 1 volt on the input to the ECU and then increase with engine speed and load. If the voltages are more than 2 volts at idle and quickly go up to 5 volts or higher, then most likely the MAP sensor is bad and needs replacement
Common mistakes when diagnosing the P0108 code
Diagnostic errors are largely due to not following the test procedure. First, follow the procedure in the diagnosis to ensure there is the correct voltage to the sensor and from the sensor to the ECU.
The technician must verify that the voltage output of the MAP Sensor is in the correct range, fluctuates with the engine speed, and has proper voltage. Idle voltage is normally 1 to 1.5 volts and full throttle is usually around 4.5 volts.
Do not buy a new MAP Sensor or ECU unless it is clearly at fault.
How serious is the P0108 code?
The P0108 code will result in poor running of the engine and requires immediate attention. The MAP sensor high voltage output issue can cause excessive fuel consumption, rough operation, backfiring, difficulty starting in certain circumstances, and can cause other damage if continued to be driven.
Often times, if the Check Engine Light came on immediately at startup, then the OBD- II system can be reset and the vehicle will operate normally.
What repairs can fix the P0108 code?
The most common potential repairs to address the P0108 code are as follows:
Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train.
If the Check Engine Light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.
https://www.yourmechanic.com/articl...uit-high-voltage-input-problem-by-john-nelson
Manifold Air Pressure (MAP) Barometric Pressure Sensor Circuit High Voltage Input Problem
What the P0108 code means
P0108 is the code for a problem with the MAP electrical circuit sensor having too high voltage input to the Engine Control Unit (ECU). This means that the voltage input to the ECU is too high and that it is not in the correct range for proper engine operation to work with inputs from the Mass Air Flow Sensor (MAF) and Throttle Position Switch (TPS).
What causes the P0108 code?
The MAP circuit input to the ECU is too high problem may have several causes:
- The source of the problem is that the sensor range voltage input is higher than what’s required by the ECU, generally above 5 volts.
- The most common problem is a bad MAP sensor.
- The wiring or connector may be bad or have a bad connection, or could be too close to higher voltage consumption components, especially alternators, ignition wires, etc. which causes elevated voltage readings. A poor electrical ground can cause problems also.
- The sensor itself may be simply operating out of range from age or damage to the sensor’s internal components.
- MAP sensors must operate within specific ranges to send correct signals for the ECU to coordinate with the throttle position sensor so it can adjust correctly for proper engine operation. The specified range is .5 to 5 volts.
- If the engine is not in good condition, is missing, has poor fuel pressure, or has an internal issue with the engine like a burned valve, these things can prevent the MAP sensor from getting a correct output. The ECU could also be bad but that is rare.
P0108 code will be generally preceded by the Check Engine Light coming on the dashboard instrument display. The vehicle will most often not run well, idle poorly, accelerate erratically, have excessive fuel consumption, or backfire because the MAP sensor and throttle position sensor are not operating together.
How does a mechanic diagnose the P0108 code?
P0108 is diagnosed with an OBD-II scanner. A qualified technician should then reset the OBD-II fault codes and road test the vehicle to see if the code comes back. He can observe this by watching live streaming on his scanner while driving. If the code comes back, then the mechanic will need to do a voltage test with the key turned on, using a multimeter, and verifying that there is 5 volts input to the MAP sensor and a minimum of .5 to 1 volt with throttle closed.
With the engine running at idle, it should have minimum 1 volt on the input to the ECU and then increase with engine speed and load. If the voltages are more than 2 volts at idle and quickly go up to 5 volts or higher, then most likely the MAP sensor is bad and needs replacement
Common mistakes when diagnosing the P0108 code
Diagnostic errors are largely due to not following the test procedure. First, follow the procedure in the diagnosis to ensure there is the correct voltage to the sensor and from the sensor to the ECU.
The technician must verify that the voltage output of the MAP Sensor is in the correct range, fluctuates with the engine speed, and has proper voltage. Idle voltage is normally 1 to 1.5 volts and full throttle is usually around 4.5 volts.
Do not buy a new MAP Sensor or ECU unless it is clearly at fault.
How serious is the P0108 code?
The P0108 code will result in poor running of the engine and requires immediate attention. The MAP sensor high voltage output issue can cause excessive fuel consumption, rough operation, backfiring, difficulty starting in certain circumstances, and can cause other damage if continued to be driven.
Often times, if the Check Engine Light came on immediately at startup, then the OBD- II system can be reset and the vehicle will operate normally.
What repairs can fix the P0108 code?
The most common potential repairs to address the P0108 code are as follows:
- Verify the code with a scanner. Then reset the fault codes and perform a road test with a scanner attached with live data streaming.
- If the P0108 code comes back, then follow the test procedure.
- Check the MAP sensor voltage, which is normally 5 volts in and .5 out at idle, and a maximum of 5 volts to the ECU. Also check the electrical connector and wiring. Disconnect the electrical connector and then reinstall it to ensure a fresh electrical connection. Then check the voltage output on the MAP sensor to see if it is in the correct range.
- At this point it is necessary to determine if the MAP sensor is defective and if it has no or incorrect output, then replace the sensor. If all checks are good, then a final test to determine if the ECU is bad must be done.
Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train.
If the Check Engine Light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.
https://www.yourmechanic.com/articl...uit-high-voltage-input-problem-by-john-nelson
P0300 code definition
Random/multiple cylinder misfire detected
What the P0300 code means
Most vehicles will have 4-6 cylinders. Each cylinder will fire a spark plug, one after another, in a smooth and continuous manner. The spark plug fires a spark, using the flammable fuel air mixture, and sets fire to the fuel. The fuel then releases energy that powers the crankshaft, which must continuously turn smoothly as the car is moving.
If more than one cylinder misfires, this will increase or decrease the revolutions per minute (RPM) of the crankshaft. If that increase and/or decrease is more than 2 percent, the Powertrain Control Module will store the P0300 trouble code.
If the percentage of the increase or decrease in revolutions per minute (RPM) is between 2 percent and 10 percent, the Check Engine Light will come on. If the percentage of the increase or decrease in revolutions per minute (RPM) is greater than 10 percent, the Check Engine Light will blink on and off, as to alert the driver of a more serious misfiring problem. The P0300 trouble code indicates that there is a misfire in random or multiple cylinders.
What causes the P0300 code?
One common mistake is ruling out the possibility of a faulty cylinder, fuel injector, or PCM. It is also common that the diagnosis and repair of other related trouble codes, is not completed.
Other related trouble codes, a faulty cylinder, a faulty fuel injector(s), and/or a faulty PCM can all cause the misfiring problem.
How serious is the P0300 code?
The P0300 trouble code is considered serious. The reason for this is the resulting driveability problems that are present when this trouble code is stored in the PCM. The car may not start and/or cause hazardous conditions during the operation of the vehicle. For these reasons, the P0300 trouble code requires immediate attention.
What repairs can fix the P0300 code?
Do not assume that the spark plugs and wires are responsible for the P0300 trouble code. There are other components of the system that could cause this error code that should be diagnosed and inspected prior to repair.
Also, there are other related trouble codes that could cause the P0300. After repairs, if the P0300 trouble code returns, inspect and diagnose these other trouble codes if applicable. Always test drive the vehicle to see if the P0300 trouble code returns after making any repairs.
Make sure the spark plugs are gapped properly and with precision. To gap the spark plugs properly, it will be necessary to use a feeler gauge.
If the spark plug gap is not precise, this will cause a misfire.The vehicle manufacturer provides the spark plug gap specifications. These specifications can be found on a sticker under the hood of the vehicle or obtained from any local part store.
https://www.yourmechanic.com/articl...le-cylinder-misfire-detected-by-jamahl-walker
Random/multiple cylinder misfire detected
What the P0300 code means
Most vehicles will have 4-6 cylinders. Each cylinder will fire a spark plug, one after another, in a smooth and continuous manner. The spark plug fires a spark, using the flammable fuel air mixture, and sets fire to the fuel. The fuel then releases energy that powers the crankshaft, which must continuously turn smoothly as the car is moving.
If more than one cylinder misfires, this will increase or decrease the revolutions per minute (RPM) of the crankshaft. If that increase and/or decrease is more than 2 percent, the Powertrain Control Module will store the P0300 trouble code.
If the percentage of the increase or decrease in revolutions per minute (RPM) is between 2 percent and 10 percent, the Check Engine Light will come on. If the percentage of the increase or decrease in revolutions per minute (RPM) is greater than 10 percent, the Check Engine Light will blink on and off, as to alert the driver of a more serious misfiring problem. The P0300 trouble code indicates that there is a misfire in random or multiple cylinders.
What causes the P0300 code?
- Spark plugs that are damaged or worn
- Spark plug wires and/or coils that are damaged or worn
- Distributor cap that is damaged or worn (only if applicable to the vehicle)
- Rotor button that is damaged or worn (only if applicable to the vehicle)
- Fuel injectors that are defective
- EGR valves or tubes that are clogged
- Ignition timing that is off
- Vaccum leaks
- Fuel pressure that is low
- Head gasket(s) that are leaking
- Distributor cap that is cracked
- Camshaft sensor that is faulty
- Crankshaft sensor that is faulty
- Mass air flow sensor that is faulty
- Oxygen sensor that is faulty
- Throttle position sensor that is faulty
- Catalytic converter that is faulty
- PCM is faulty
- Check Engine Light that is on or flashing
- Car may take longer to start up, or does not start up at all
- Car dies while stopped
- Car idles rough
- Car may hesitate while accelerating
- Lack of power while driving
- Increase of fuel consumption
- Uses OBD-II scanner to retrieve freeze frame data and all of the trouble codes that have been stored by the Primary Control Module (PCM)
- Completes a test drive of the vehicle to see if the P0300 trouble code comes back
- Reviews live data to identify which cylinders are showing misfire data
- Inspects spark plug wires or coil packs for wiring that is damaged or worn
- Inspects spark plugs for excessive wear, cracks, or breaks
- Inspects coil pack wiring at the harness and connector, for breaks, or corrosion
- Replaces spark plugs, spark plug wires, coil packs, coil pack wiring at harness and connector, as necessary
- If the P0300 trouble code is still present after the spark plugs, spark plug wires and/or coil packs have been replaced, they will inspect the fuel injectors and fuel injector system for faults
- Older vehicles have a distributor cap and rotor button system. For these vehicles, the mechanic will inspect the distributor cap and rotor button for damage, cracks, or excessive wear
- If other related trouble codes have been stored by the PCM, the mechanic will need to diagnose and repair these issues as necessary. Test drive the vehicle again to see if the P0300 trouble code comes back.
- If the P0300 trouble code returns, the compression system should be checked. A fault in the compressor is rare but possible for this code.
- If the P0300 trouble code still persists, there could be a problem with the PCM. This may require replacing or reprogramming. This is also rare.
One common mistake is ruling out the possibility of a faulty cylinder, fuel injector, or PCM. It is also common that the diagnosis and repair of other related trouble codes, is not completed.
Other related trouble codes, a faulty cylinder, a faulty fuel injector(s), and/or a faulty PCM can all cause the misfiring problem.
How serious is the P0300 code?
The P0300 trouble code is considered serious. The reason for this is the resulting driveability problems that are present when this trouble code is stored in the PCM. The car may not start and/or cause hazardous conditions during the operation of the vehicle. For these reasons, the P0300 trouble code requires immediate attention.
What repairs can fix the P0300 code?
- Replacing damaged spark plugs
- Replacing damaged or worn spark plug wires and/or coils
- Repairing or replacing clogged EGR valves and/or tubes
- Repairing vacuum leaks
- Repairing or replacing leaking head gaskets
- Replacing faulty camshaft sensor
- Replacing faulty crankshaft sensor
- Replacing faulty mass air flow sensor
- Replacing faulty oxygen sensor
- Replacing faulty throttle position sensor
- Replacing faulty fuel injectors
- Replacing faulty catalytic converter
- Diagnosing and repairing other related trouble codes
- Replacing distributor cap and rotor button, as well as wires, coils, and plugs, (only if applicable to the vehicle)
- If necessary, repair fault internal engine components.
- Replacing engine (if cylinder damage exists)
- Replacing a faulty PCM
Do not assume that the spark plugs and wires are responsible for the P0300 trouble code. There are other components of the system that could cause this error code that should be diagnosed and inspected prior to repair.
Also, there are other related trouble codes that could cause the P0300. After repairs, if the P0300 trouble code returns, inspect and diagnose these other trouble codes if applicable. Always test drive the vehicle to see if the P0300 trouble code returns after making any repairs.
Make sure the spark plugs are gapped properly and with precision. To gap the spark plugs properly, it will be necessary to use a feeler gauge.
If the spark plug gap is not precise, this will cause a misfire.The vehicle manufacturer provides the spark plug gap specifications. These specifications can be found on a sticker under the hood of the vehicle or obtained from any local part store.
https://www.yourmechanic.com/articl...le-cylinder-misfire-detected-by-jamahl-walker
devildodge
Well-known member
I see from another post you do have a scan tool. If it has live data, do a little research and learn what the values mean and take a ride safely watching the info...mine has record also so you can look at it all when you get back.
It isn't rare that replacement parts...especially electrical...aren't well.
If you can check the operation of the sensors you put on, with the info @redriderbob gave above.
Make sure you have all other wires routed away from each other.
I am not very familiar with jeeps, but I have done a lot of this with my 99 V10. Not a lot of info on that, so I did a lot of training myself on the ins and outs of the motor.
Look at wiring diagrams, and those O2 sensors can really screw with everything.
But don't just throw more parts at it. Check them with the specs.
Good luck. If I can offer anymore help I will try my best.
It isn't rare that replacement parts...especially electrical...aren't well.
If you can check the operation of the sensors you put on, with the info @redriderbob gave above.
Make sure you have all other wires routed away from each other.
I am not very familiar with jeeps, but I have done a lot of this with my 99 V10. Not a lot of info on that, so I did a lot of training myself on the ins and outs of the motor.
Look at wiring diagrams, and those O2 sensors can really screw with everything.
But don't just throw more parts at it. Check them with the specs.
Good luck. If I can offer anymore help I will try my best.
devildodge
Well-known member
Oh, and always remember to get the brand listed as OEM. I bought Bosh sensors for my truck thinking they are good...turns out the V10 really does have to use NGK components