GENERAL DESCRIPTION
This system is provided with two ignition coils (A and B) with built-in ignition power transistors for the number 1 and number 4 cylinders, and number 2 and number 3 cylinders respectively.
Interruption of the current flowing in the primary side of ignition coil A generates a high voltage in the secondary side of ignition coil A.
The high voltage generated is applied to the spark plugs of number 1 and number 4 cylinders to generate sparks. At the time that the sparks are generated at both spark plugs, if one cylinder is at the compression stroke, the other cylinder is at the exhaust stroke, so that ignition of the compressed air/fuel mixture occurs only for the cylinder which is on the compression stroke.
In the same way, when the primary current flowing in ignition coil B is interrupted, the high voltage thus generated is applied to the spark plugs of number 2 and number 3 cylinders.
The engine control module controls the two ignition power transistors to turn them alternately ON and OFF. This causes the primary currents in the ignition coils to be alternately interrupted and allowed to flow to fire the cylinders in the order 1 - 3 - 4 - 2.
The engine control module determines which ignition coil should be controlled by means of the signals from the camshaft position sensor and from the crankshaft position sensor.
It also detects the crankshaft position in order to provide ignition at the most appropriate timing in response to the engine operation conditions.
When the engine is cold or operated at high altitudes, the ignition timing is slightly advanced to provide optimum performance.
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SPECIAL TOOL
SPECIAL TOOL TOOL TOOL NUMBER AND NAME SUPERSESSION APPLICATION MD998773 Knock sensor wrench MD998773-01 Knock sensor removal and installation
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KNOCK CONTROL SYSTEM CHECK
Check the knock sensor circuit if diagnostic trouble code, No. P0325 is shown.
Refer to DTC P0325: KNOCK SENSOR CIRCUIT .
IGNITION COIL CHECK
Check by the following procedure, and replace the coil if there is a malfunction.
SECONDARY COIL RESISTANCE CHECK
Measure the resistance between the high-voltage terminals of the ignition coil.
Standard value: 8.5 - 11.5 kohms
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Note. An analog-type ohmmeter should be used.
Note. Connect the negative probe of the ohmmeter to terminal No. 1.
| CAUTION | This test must be performed quickly (in less than 10 seconds) to prevent coil from burning and ignition power transistor from breaking. |
- Connect and disconnect 1.5 V battery between terminals No. 2 and No. 3, and observe the ohmmeter whether there is continuity or not.
- If results do not agree with the table below, replace the primary coil and ignition power transistor assembly. CONTINUITY REFERENCE CHART 1.5 V POWER SUPPLY BETWEEN 2 - 3 CONTINUITY BETWEEN 1 - 2 Current flowing Yes Current not flowing No
SPARK PLUG CABLE RESISTANCE CHECK
Measure the resistance of the all spark plug leads.
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- Check the cap and coating for cracks.
- Measure the resistance. Limit: 19 kohms
- If resistance is greater than 19 kohms, replace the cable.
SPARK PLUG CHECK AND CLEANING
| CAUTION | Do not attempt to adjust the gap of the iridium plug. Cleaning of the iridium plug may result in damage to the iridium and platinum tips. Therefore, if carbon deposits must be removed, use a plug cleaner and complete cleaning within 20 seconds to protect the electrode. Do not use a wire brush. |
Check the plug gap and replace if the limit is exceeded.
Standard value: 0.5 - 0.6 mm (0.020 - 0.024 inch)
Limit: 0.75 mm (0.0295 inch)
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CAMSHAFT POSITION SENSOR CHECK
Refer to DTC P0340: CAMSHAFT POSITION SENSOR CIRCUIT .
CRANKSHAFT POSITION SENSOR CHECK
MEASUREMENT METHOD
- Clamp the spark plug cable (Number 1 or 3) with the secondary pickup. NOTE: Because of the two-cylinder simultaneous ignition system, the waves for two cylinders in each group appear during wave observation. However, wave observation is carried out for the cylinder (Number 1 or 3) with the spark plug cable which has been clamped by the secondary pickup. NOTE: Identification of which cylinder wave pattern is displayed can be difficult, but the wave pattern of the cylinder which is clamped by the secondary pickup will be stable, so this can be used as a reference.
- Clamp the spark plug cable (Number 1 or 3) with the trigger pickup. NOTE: Clamp the same sparkplug cable as the one which has been clamped by the secondary pickup.
STANDARD WAVE PATTERN
| Settings | |
|---|---|
| FUNCTION | SECONDARY |
| Pattern height | High (or low) |
| Pattern selector | Raster |
| Engine speed | Curb idle speed |
STANDARD WAVEFORM CHART
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ABNORMAL WAVEFORMS EXAMPLES
Example 1
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- Wave characteristics: Spark line is high and short.
- Cause of problem: Spark plug gap is too large.
Example 2
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- Wave characteristics: Spark line is low and long, and is sloping. Also, the second half of the spark line is distorted. This could be a result of misfiring.
- Cause of problem: Spark plug gap is too small.
Example 3
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- Wave characteristics: Spark line is low and long, and is sloping. However, there is almost no spark line distortion.
- Cause of problem: Spark plug gap is fouled.
Example 4
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- Wave characteristics: Spark line is high and short. Difficult to distinguish between this and abnormal wave pattern example 1.
- Cause of problem: Spark plug cable is not properly connected. (Causing a dual ignition)
Example 5
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- Wave characteristics: No waves in wave damping section
- Cause of problem: Short in ignition coil.
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REMOVAL AND INSTALLATION
| CAUTION | During maintenance, take care not to contact the parts or tools to the caliper because the paint of caliper will be scratched. |
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<< A >> POWER STEERING OIL PUMP, BRACKET AND OIL RESERVOIR ASSEMBLY REMOVAL
Note. Tie the removed power steering oil pump, bracket and oil reservoir assembly with a rope and set aside where they cannot hinder the removal of the power steering oil pump bracket.
Remove the power steering oil pump, bracket and oil reservoir assembly with the hoses attached from the power steering oil pump bracket.
| CAUTION | When the knock sensor replacement is performed, use scan tool MB991958 to initialize the learning value (Refer to INITIALIZATION PROCEDURE FOR LEARNING VALUE IN MFI ENGINE ). |
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Required Special Tool
- MD998773: Knock Sensor Wrench
<< A >> KNOCK SENSOR REMOVAL
Use special tool MD998773 to remove the knock sensor.
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<< A >> KNOCK SENSOR INSTALLATION
Use special tool MD998773 to install the knock sensor.