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Problem after engine warms up on my Omega CD 3.8 1999 (Holden Commodore VT)

Alexandre Perrotto

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Good morning everyone, I have a problem with my Omega CD 3.8 1999 (Holden Commodore VT), I turn on the engine in the morning and it works normally, I drive the car, it reaches normal operating temperature and has no problems, now , when I turn it off and on again, still hot, it has the following problems, failure to accelerate (as if a cylinder was missing), at that moment the check engine light comes on and the idle speed is totally unregulated, even turning off the engine when it starts for the vehicle in gear, if I leave it parked and I'll turn it on the other day, after resetting the light, it doesn't have a problem, that is, it's just hot it does that. Has anyone had this problem or can help me solve it, remembering that I already changed the camshaft sensor thinking that was the problem but it didn't solve it.
 

lout

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it is usually crankshaft sensor not camshaft that causes problems
if you had a cel you would have a code which will tell you where to test
 

Alexandre Perrotto

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Thank you for your attention, I also thought about it but I don't know how to remove the crankshaft pulley to change these sensors, as for the code, the problem is that I'm in Brazil, and I have 3 scanners but none of them connects to the OBD2 port of the Omega (Holden Commodore VT), only in specialized workshops with expensive scanners and in the region where I am, there are none, I thought about buying the cable to connect to the laptop, because I have the TunerPro, it happens that they ask for R$ 300.00 here, almost 90.00 Australian dollars and they don't guarantee it works, so I was lost, but I'll try to take the pulley out and change the sensor. I really appreciate the attention.
 

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bridging pin 5 and 6 in obd port will then flash cel
count the number of flashes and that is your code
 

Alexandre Perrotto

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Good afternoon, I did the test by making a jumper between pin 5 and 6, it flashes code 12 three times then it flashes code 42, which by the error table would be:
* 42 Electronic spark timing (EST) bypass circuit
 

Alexandre Perrotto

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From what I searched

- Distributor grounding, battery voltage greater than 12.5 V;

- Check the conditions of the HAI module harness, coil, spark plugs, cables, distributor, hall sensor (when replacing some of these components, apply good quality parts)

Just letting you know that I changed the battery, and put a 70amp one, could this be it?
 

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Thank you for your attention, I also thought about it but I don't know how to remove the crankshaft pulley to change these sensors
It's unlikely to be anything to do with the crank or cam sensors or the battery, the symptoms you describe are not really symptoms of either of these. More likely to be that you're Idle Air Control valve is gummed up or has stopped working which lets in a bunch of air when it's open which increase idle speed, and if it stays closed will make it conk out when stopped or not using the accelerator. Try cleaning or replacing that.

I have 3 scanners but none of them connects to the OBD2 port of the Omega
The V6s have use ALDL with an OBD2 plug, the scanner you use needs to support ALDL. You won't get any more info than what you do from using a paperclip to get the check engine light to flash though.
 

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code 42 refers to the dfi module not receiving the bypass signal from the ecu
so most likely cause would be the plug connector to the dfi module or a faulty dfi module
do you have a friend you can swap dfi with to test
this is the holden diagnostics
circuit 423 is dis pin A
circuit 424 is dis pinB


CIRCUIT DESCRIPTION:
There are two modes of ignition system operation: BYPASS mode, and ELECTRONIC SPARK TIMING mode. The
Bypass mode is normally used while starting the engine, while the Electronic Spark Timing mode is used to allow
the PCM to control the ignition system after the engine is running. The PCM controls a "Bypass control circuit", used
to control the ignition module between the two different ignition system modes.
The PCM's Electronic Spark Timing (EST) output circuitry generates EST output pulses anytime crankshaft
reference input pulses are received. The PCM also monitors it's EST output terminal, to monitor if and when EST
pulses are present.
When the ignition system is operating in the Bypass mode (such as when the engine is cranking), the ignition
module earths the EST pulses coming from the PCM. Because the EST pulses should be earthed through the
ignition module during Bypass mode operation., the PCM should not detect EST pulses on it's EST output terminal.
When the engine is started, the PCM applies 5 volts to the Bypass control circuit. When received by the ignition
module, this 5 volts control causes the ignition module to release the earth from the EST pulses coming from the
PCM. The ignition module will then use the EST pulses to operate the ignition system. When this occurs, the PCM
will correctly detect EST pulses at it's EST output terminal.
If the Bypass control circuit has as open fault or short to earth, or if the EST circuit has a short to earth or short to
voltage, the PCM cannot control the ignition module to release the EST pulses from being earthed. Because the
PCM also monitors it's EST output terminal for EST pulses, if it detects no EST pulses after it has "turned on" the 5
volts to the Bypass control circuit, and the engine speed goes above 1600 RPM, a DTC 42 will be set.
DTC 42 WILL SET IF:
• Engine speed is greater than 1600 RPM.
• PCM has detected no EST output pulses for 200 milliseconds.
TEST DESCRIPTION:
Number(s) below refer to Step numbers on the Diagnostic chart.
4. This step checks to see if circuit 423 is shorted to voltage.
7. This step checks to see if circuit 423 is shorted to earth.
10. This step checks to see if circuit 424 is shorted to earth.
12. This step checks to see if circuit 424 is open.
13 This step checks to see if the ignition module is capable of switching from Bypass to EST mode.
DIAGNOSTIC AIDS:
• Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poor terminal to wire connection.
• Damaged Harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the
ignition module, turn the ignition "ON". Connect and observe a voltmeter connected between the Bypass control
circuit and B+, while moving connectors and wiring harness related to the ignition module. A change in voltage
will indicate the location of the fault.
STEP ACTION VALUE YES NO
1. Was the "On-Board
Diagnostic" (OBD) System
Check performed?
Go to Step 2. Go to OBD
System Check.
2. 1. Clear DTC 42.
2. Start engine, and run
above 1600 RPM.
3. Observe DTC(s).
Did DTC 42 set ?
Go to Step 3 DTC 42 is
intermittent. Refer
to "Diagnostic
Aids" above.
3. 1. Ignition "OFF".
2. Disconnect ignition
module 14 pin
connector.
3. Probe ignition module
harness connector
terminal "A" with a
voltmeter to earth.
4. Ignition "ON".
Is voltage greater then the
specified value?
0.5 V Go to Step 4 Go to Step 6
4. 1. Ignition "OFF".
2. Disconnect PCM
connectors.
3. Ignition "ON".
Is voltage still present at
ignition module harness
connector terminal "A" ?
Go to Step 5 Go to Step 15
5. Repair short to voltage on
circuit 423.
Is action complete ?
Verify Repair
6. 1. Ignition "ON".
2. Probe ignition module
harness connector
circuit 423 with a test
light connected to
battery voltage.
Is test light "ON" ?
Go to Step 7 Go to Step 9
7. 1. Ignition "OFF
2. Disconnect PCM
connectors.
3. Probe ignition module
connector circuit 423
with a test light
connected to battery
voltage.
Is test light "ON" ?
Go to Step 8 Go to Step 14
8. Repair short to earth in
circuit 423.
Is action complete
Verify Repair
9. 1. Ignition "ON".
2. Disconnect ignition
module 14 pin
connector.
3. With test light
connected to battery
voltage, probe ignition
module harness
connector circuit 424.
Is test light "ON" ?
Go to Step 10 Go to Step 12
STEP ACTION VALUE YES NO
10. 1. Ignition "OFF".
2. Disconnect PCM
connectors.
3. Ignition "ON".
4. Disconnect ignition
module 14 pin
connector.
5. With test light
connected to battery
voltage, probe ignition
module harness
connector circuit 424.
Is test light "ON" ?
Go to Step 11 Go to Step 14
11. Repair short to earth on
circuit 424.
Is action complete ?
Verify Repair
12. 1. Ignition "OFF".
2. Disconnect PCM
connectors.
3. Check for faulty
connection or open
circuit 424.
Is fault found ?
Verify Repair Go to Step 13
13. 1. Ignition "OFF".
2. Reconnect ignition
module 14 pin
connector.
3. Disconnect PCM
connectors.
4. Ignition "ON".
5. Probe PCM harness
connector circuit 423
with an ohmmeter
connected to earth.
5. Probe PCM harness
connector circuit 424
with a test light
connected to battery
voltage.
NOTE:
As the test light contacts
circuit 424, does
resistance switch from
under specified value to
over specified value?
300
ohms
to
6000
ohms
Go to Step 14 Go to Step 15
14. Replace PCM.
Refer to Section 6C1-3
Service Operations, for
PCM Security Link
procedure.
Is action complete?
Verify Repair
15. Replace ignition module.
Is action complete ?
Verify Repair
 
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