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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
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Experience:  Have owned a repair shop for 25 yrs.
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2001 malibu: replaced plugs,wires,module and coils.

Resolved Question:

2001 malibu 3.1 has weak spark. replaced plugs,wires,module and coils. almost starts. what tests can i run? could it be crank sensor or ecm? thanks for your help, Ron.
Submitted: 5 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 5 years ago.
hi ron
please explain to me how and when it quit running?
tell me all you can
Customer: replied 5 years ago.
my son shut it off and it never started far as i know it ran fine before.
Expert:  Tim's Auto Repair replied 5 years ago.
do you here the fuel pump come on for 2 seconds when you first turn the key on?
will it start and run for a few seconds if you spray starting fluid into the throttle body?
Customer: replied 5 years ago.
it has 50 psi fuelpressure at schrader valve, it acts like it will start but doesnt when ether is sprayed into tb
Expert:  Tim's Auto Repair replied 5 years ago.
you need to first check the compression on a cylinder...just to make sure it hasnt maybe jumped time,,,,,
yes,a bad 7x crank sensor could cause this
2001 Chevrolet Malibu V6-3.1L VIN J
Compression Check Specifications, Pressure, Vacuum and Temperature

Minimum Compression Pressure 100 psi
Note: -- The lowest reading should not be less than 70 percent of the highest reading.

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Customer: replied 5 years ago.
ok, i'll check compression. am i right about orange spark indicating ignition is weak? shouldn't it be blue and snap when sparking? can i test the crank sensor at the module with an ohmeter? is sensor located at balancer? thanks, Ron.
Expert:  Tim's Auto Repair replied 5 years ago.
the spark on these are usally a orangy looking.....
this engine has 2 crank sensors a 24x and a 7x...the 7x is in the side of the engine block..note the picture i sent earlier
2001 Chevrolet Malibu V6-3.1L VIN J
Computers and Control Systems Testing and Inspection, Component Tests and General Diagnostics: Electronic Ignition (EI) System Diagnosis
The Ignition Control (IC) module has independent power and ground circuits. The circuits between the IC module and the Powertrain Control Module (PCM) consist of the following circuits:
^ The IC timing signal
^ The IC timing control
^ The low-resolution engine speed signal
^ A low reference signal

The Ignition Control (IC) module sends 3x signals to the Powertrain Control Module (PCM). The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:
^ The PCM receives the second 3x signal.
^ The PCM applies 5 volts to the IC timing signal circuit.
^ The timing advance switches to PCM control.


Steps 1-5

Steps 6-15

Steps 16-23

The numbers below refer to the step numbers on the diagnostic table.
2. It is necessary to disconnect the 24X crank sensor to ensure that the 7X signal is being read in the 3X reference parameter on the scan tool.
3. The J 26792 spark tester presents a more difficult load on the secondary ignition than a normal spark plug. If a miss, stumble, or hesitation is being caused by a spark plug not firing, the spark tester should also not tire.
4. Use a 5 percent saltwater solution in a spray bottle to induce voltage arching to ground through faulty insulation of spark plug wires.
6. If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test could also be performed by substituting a known good coil for the one causing the no spark condition.