NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISE [L3]

BME010300103250

12

LACK/LOSS OF POWER - ACCELERATION/CRUISE

DESCRIPTION

Performance is poor under load (e.g., power down when climbing hills).

POSSIBLE CAUSE

• Improper A/C system operation
• Erratic signal or no signal from CMP sensor
• Air leakage from intake-air system parts
• Improper VIS operation
• Improper VTCS operation
• Purge control solenoid malfunction
• EGR valve malfunction
• Brake dragging
• Erratic signal from CKP sensor
• Low engine compression
• Vacuum leakage
• Poor fuel quality
• Spark leakage from high-tension leads
• Engine overheating
• Throttle body malfunction
• Spark plug malfunction
• Air cleaner restriction
• PCV valve malfunction
• Improper valve timing due to jumping out of timing belt
• Restriction in exhaust system
• Intermittent open or short in fuel pump related circuit
• Inadequate fuel pressure
• Fuel pump mechanical malfunction
• Fuel line restriction or clogging
• Fuel leakage from fuel injector
• Fuel injector clogging
• Intermittent open or short of MAF sensor, TP sensor and VSS
• Clutch slippage
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual.
(See BEFORE SERVICE PRECAUTION [L3].)
(See AFTER SERVICE PRECAUTION [L3].)
Caution
• Disconnecting/connecting quick release connector without cleaning it may possibly cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Verify the following:
• Vacuum connection
• Air cleaner element
• No air leakage from intake-air system
• No restriction of intake-air system
• Proper sealing of intake manifold and components attached to intake manifold; such as EGR valve, IAC valve
• Fuel quality (e.g. proper octane, contamination, winter/summer blend)
Are all items normal?
Yes
Go to the next step.
No
Service if necessary.
Repeat Step 1.
2
Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
If the engine stall condition exists, retrieve continuous memory and KOEO DTCs.
Are there any DTCs displayed?
Yes

DTC is displayed:

Go to the applicable DTC inspection.
No

No DTC is displayed:

Go to the next step.
3
Is the engine overheating?
Yes
Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".
No
Go to the next step.
4
Connect the WDS or equivalent to the DLC-2.
Access RPM, MAF, TP and VSS PIDs.
Drive the vehicle while monitoring PIDs.
Are PIDs within the specifications?
Yes
Go to the next step.
No

RPM PID:

Inspect the CKP sensor and the related wiring harness for vibration and/or intermittent open/short circuit.

MAF PID:

Inspect for intermittent open circuit of the MAF sensor and the related wiring harness.

TP PID:

Inspect if the TP sensor output increases smoothly.

VSS PID:

Inspect for intermittent open circuit of the VSS and the related wiring harness.
5
Visually inspect the CKP sensor and teeth of the crankshaft pulley.
Are the CKP sensor and teeth of the crankshaft pulley normal?
Yes
Go to the next step.
No
Replace the malfunctioning part.
6
Measure the gap between the CKP sensor and teeth of the crankshaft pulley.
Specification

0.5-1.9 mm {0.020-0.075 in}

Is the gap within the specification?
Yes
Go to the next step.
No
Adjust the CKP sensor.
7
Inspect the spark plug condition.
Is the spark plug wet, covered with carbon or grayish white?
Yes

Spark plug is wet or covered with carbon:

Inspect for fuel leakage from the fuel injector.

Spark plug is grayish white:

Inspect for the clogged fuel injector.
No
Install the spark plugs on original cylinders.
Go to the next step.
8
Remove and shake the PCV valve.
Does the PCV valve rattle?
Yes
Go to the next step.
No
Replace the PCV valve.
9
Inspect for restriction in the exhaust system.
Is there any restriction?
Yes
Inspect the exhaust system.
No
Go to the next step.
10
Install a fuel pressure gauge between the fuel pipe and the fuel distributor.
Connect a jumper wire between F/P terminal at the DLC-2 in the engine compartment and GND.
Turn the ignition switch to the ON position.
Is fuel line pressure correct with the ignition switch at the ON position?
Yes
Go to the next step.
No

Zero or low:

Inspect for clogged fuel line.
If normal, replace the fuel pump unit.

High:

Replace the fuel pump unit.
11
Inspect the VTCS operation.
Does the VTCS work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
12
Inspect the VIS operation.
Does the VIS work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
13
Note
• The following test is for the engine stalling with A/C on concern. If other symptoms exist, go to the next step.
Connect a pressure gauge to the A/C low and high side pressure lines.
Turn the A/C on and measure low side and high side pressures.
Are pressures within the specifications?
Yes
Go to the next step.
No
If the A/C is always on, go to symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously".
For other symptoms, inspect the following:
• Refrigerant charging amount
• Condenser fan operation
14
Inspect for the A/C cut-off operation.
Does the A/C cut-off work properly?
Yes
Go to the next step.
No
Inspect the A/C cut-off system components.
15
Disconnect vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug opening end of vacuum hose.
Drive the vehicle.
Does the engine condition improve?
Yes
Inspect if the purge solenoid valve is sticks open mechanically.
Inspect the evaporative emission control system.
No
Go to the next step.
16
Visually inspect the CMP sensor and projections of the camshaft pulley.
Are the CMP sensor and projections of the camshaft pulley normal?
Yes
Go to the next step.
No
Replace the malfunctioning part.
17
Inspect the EGR system.
Is the EGR system normal?
Yes
Go to the next step.
No
Replace the malfunctioning part.
18
Is the engine compression correct?
Yes
Inspect the following:
• Valve timing
• Clutch
• Brake system for dragging
No
Inspect for cause.
19
Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM.