| Step |
Action |
Value(s) |
Yes |
No |
| DEFINITION: Engine runs unevenly at
idle. If severe, the engine or vehicle may shake. Engine idle speed may
vary in RPM. Either condition may be severe enough to stall the engine.
|
| 1 |
Was the Powertrain On-Board Diagnostic (OBD)
System Check performed? |
-- |
Go
to Step 2 |
Go to the A
Powertrain On Board Diagnostic (OBD) System Check |
| 2 |
- Perform a bulletin search.
- If a bulletin that addresses the symptom is found, correct
the condition as instructed in the bulletin.
Was a bulletin
found that addresses the symptom? |
-- |
Go
to Step 13 |
Go
to Step 3 |
| 3 |
Was visual/physical check performed? |
-- |
Go
to Step 4 |
Go to Visual /Physical check in Symptoms
|
| 4 |
- Check PCM grounds for being clean, tight and proper routing.
Refer to PCM
Power and Ground Check .
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 5 |
| 5 |
Observe Long Term FT on the scan tool. Is Long
Term FT significantly in the negative range (Rich condition)? |
-- |
Go
to Step 6 |
Go
to Step 7 |
| 6 |
- Check items that can cause the engine to run rich.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 9 |
| 7 |
Is Long Term FT significantly in the positive
range (Lean condition)? |
-- |
Go
to Step 8 |
Go
to Step 9 |
| 8 |
- Check items that can cause the engine to run lean.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 9 |
| 9 |
- Check for incorrect idle speed. Ensure that the following
conditions are present:
- Engine fully warm.
- Accessories OFF.
- Using a scan tool, monitor IAC position.
Is IAC
position within the specified values? |
5 to 50 counts |
Go
to Step 11 |
Go
to Step 10 |
| 10 |
- Visually/physically inspect for the following conditions:
- Throttle body tampering (Adjustment screw plug removed).
- Restricted air intake system. Check for a possible collapsed air
intake duct, restricted air filter element, or foreign objects
blocking the air intake system.
- Throttle body. Check for objects blocking the IAC passage or
throttle bore, excessive deposits in the IAC passage and on the IAC
pintle, and excessive deposits in the throttle bore and on the
throttle plate.
- Large vacuum leak. Check for a condition that causes a large
vacuum leak, such as a incorrectly installed or faulty crankcase
ventilation valve or brake booster hose disconnected.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 8 |
| 11 |
Check the injector connections. If any of the
injector connectors are connected to an incorrect cylinder, correct as
necessary. Was a problem found? |
-- |
Go
to Step 24 |
Go
to Step 12 |
| 12 |
- Perform the Fuel
Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35
Degrees C (50-95 Degrees F) .
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 13 |
| 13 |
- Check for fuel in pressure regulator vacuum hose.
- If fuel is present, replace the fuel pressure regulator
assembly.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 14 |
| 14 |
- Check for proper ignition coil output voltage with spark
tester J 26792 (ST 125):
- Clip the spark tester J 26792 to engine ground.
- Connect one end of a spark plug wire to the spark tester
J 26792; connect the other end of the spark plug wire to the coil
being tested.
- Connect one end of another spark plug wire to the other
coil tower; connect the other end of the spark plug wire to ground.
- Crank the engine while observing the spark tester
J 26792; a crisp blue spark should be observed.
- Repeat the above steps for each coil.
- If adequate spark is not present at all coils, repair as
necessary.
Was a problem found? |
-- |
Go
to Step 24 |
Go
to Step 15 |
| 15 |
Important
If spark plugs are gas or oil fouled, the cause of the fouling must be
determined before replacing the spark plugs.
- Remove spark plugs, check for wet plugs, cracks, wear,
improper gap, burned electrodes, or heavy deposits.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 16 |
| 16 |
- Check for loose ignition control module ground.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 17 |
| 17 |
- Check ignition coils for cracks or carbon tracking.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 18 |
| 18 |
Using a Scan Tool, monitor TP angle with the
engine idling. Is TP angle at the specified value and steady? |
0% |
Go
to Step 19 |
Go to DTC
P0123 Throttle Position (TP) Sensor Circuit High Voltage for further
diagnosis |
| 19 |
- Check crankcase ventilation valve for proper operation.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 20 |
| 20 |
- Check Transaxle Range switch circuits; use a scan tool and be
sure the scan tool indicates that the vehicle is in drive with gear
selector in drive or overdrive.
- If a problem is found, diagnose and repair Transaxle Range
switch as necessary. Refer to Shift
Lever Indicates Wrong Gear in Automatic Transaxle.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 21 |
| 21 |
- Check the following engine mechanical items. Refer to Engine
Mechanical for diagnosis procedures:
- Check compression.
- Sticking or leaking valves.
- Worn camshaft lobe(s).
- Valve timing.
- Bent push rods.
- Worn rocker arms.
- Broken valve springs.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 22 |
| 22 |
- Check for faulty engine mount. Go to Engine Mount
Inspection Engine Mechanical for inspection of mounts.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go
to Step 23 |
| 23 |
- Review all diagnostic procedures within this table.
- If all procedures have been completed and no malfunctions
have been found, review/inspect the following:
- Visual/physical inspection.
- Scan Tool data.
- Freeze Frame data/Failure Records Data.
- All electrical connections within a suspected circuit and/or
system.
- If a problem is found, repair as necessary.
Was a
problem found? |
-- |
Go
to Step 24 |
Go to the A
Powertrain On Board Diagnostic (OBD) System Check |
| 24 |
Operate the vehicle to duplicate conditions
present when the original symptom was noted. Is symptom still present? |
-- |
Go
to Step 3 |
Repair complete. |
