PO code 108, I changed the MAP sensor with no change, I have changed the IAC, with no change. Engine starts rough and the rpm goes from 500 to 2,000 while running very rich, after a minute or so the engine will actuall settle down and idle without running rich or pulsating in rpm. Any help please
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Re: 2001 Dodge 1500 4x4 fault code PO 108
If you don't find that vacuum leak,( which is a common cause too) look with a scan tool at the reading on reported intake air temperature sensor. It should be within 10 Deg of your ambient temperature.
An air temperature sensor fault can cause flooding/starving of the engine. Some of the ones I've seen will report temperatures over 50F higher than the normal air temperature and fluctuate rapidly. Such a jump really affects how the computer calculates the mixture.
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Four digit codes are brand specific. Code 2302 for a Chrysler product means the secondary circuit for the coil on cylinder one is at fault. If you have replaced the coil and plug wires, it could be a problem in the wiring harness between the coil and the engine computer.
Possible causes P406 include EGR Valve clogged, dirty or leaky
- EGR valve damaged/defective
- EGR volume control solenoid valve
- EGR temperature sensor and circuit
- EGR volume control solenoid valve harness is open or shorted
- EGR volume control solenoid valve circuit poor electrical connection
Possible causes P0108 - Faulty Manifold Absolute Pressure sensor
- Manifold Absolute Pressure harness is open or shorted
- Manifold Absolute Pressure sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)
Preliminary Checks Prior to starting this symptom test routine, inspect these underhood items:
All related vacuum lines for proper routing and integrity.
All related electrical connectors and wiring harnesses for faults (Wiggle Test).
Check the throttle linkage for a sticking or binding condition.
Air Intake system for restrictions (air inlet tubes, dirty air filter, etc.).
Search for any technical service bulletins related to this symptom.
Turn the key to off. Unplug the MAP sensor connection and restart the engine to recheck for the idle concern. If the condition is gone, replace the MAP sensor.
Test 2: Rough, Low or High Idle Speed Condition (Continued) Test 2 Chart
Step Description: Verify the rough idle or stall Does the engine have a warm engine rough idle, low idle or high idle condition in P or N-
Go to Step 2.
Fault is intermittent. Return to the Symptom List and select another fault.
Step Description: Verify idle speed & timing Verify the base timing is within specifications Verify that the base idle speed is set properly Are the timing and idle speed set properly-
Go to Step 3.
Set the base idle speed and timing to the specifications and then retest for the symptom.
Step Description: Check AIS / IAC Operation Check the AIS or IAC motor operation Inspect the AIS/IAC housing in throttle body for restricted passages. Clean as needed. Set the parking brake, block the drive wheels and turn the A/C off. Install the Scan Tool. IAC Motor Tester - Turn the key off and then connect the IAC tester to the IAC valve. Start the engine and use the IAC tester to extend and retract the IAC valve. ATM Test - Start the engine. Use the tool to change the speed from min-idle to 1500 rpm. Did the idle speed change as commanded-
Install an Aftermarket Noid light and check the operation of the PCM and AIS or IAC motor circuits. Check the motor for signs of open or shorted circuits. Replace the IAC motor or PCM as needed or make repairs to the IAC motor wiring. If all are okay, go to Step 4.
If the AIS/IAC motor passages are clean and engine speed did not change as described when the AIS/IAC motor was extended and retracted, replace the AIS/IAC motor. Then retest for the condition.
Step Description: Check/compare PID values Connect Scan Tool & turn off all accessories. Start the engine and allow it to fully warmup. Monitor all related PIDs on the Scan Tool. Verify the P/N switch input in gear and Park. Check the O2S operation with a Lab Scope. Are all PIDs within normal range-
Go to Step 5. Note: An IAC motor count of over 80 indicates the pintle is extended and an IAC count of (0) indicates the pintle is retracted.
One or more of the PIDs are out of range when compared to "known good" values. Make repairs to the system that is out of range, then retest for the symptom.
Step Description: Check the Ignition System Inspect the coils for signs of spark leakage at coil towers or primary connections. Check the spark output with a spark tester. Test Ignition system with an engine analyzer. Were any faults found in the Ignition system-
Make repairs as needed
Go to Step 6.
Step Description: Check the Fuel System Inspect the Fuel delivery system for leaks. Test the fuel pressure, quality and volume. Test the operation of the pressure regulator. Were any faults found in the Fuel system-
Make repairs as needed
Go to Step 7.
Step Description: Check the Exhaust System Check Exhaust system for leaks or damage. Check the Exhaust system for a restriction using the Vacuum or Pressure Gauge Test (e.g., exhaust backpressure reading should not exceed 1.5 psi at cruise speeds). Were any faults found in Exhaust System-
Make repairs to the Exhaust system. Then retest the symptom.
Go to Step 8.
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