LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

1996 optispark, plug and wires replacing

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Old 01-11-2021, 07:13 PM
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Re: 1996 optispark, plug and wires replacing

If the dowel pin is in the correct slot, that is all that matters. If it was in the wrong slot you should at least get some popping or backfiring when you try to start it. The spark timing would be off. I've seen/diagnosed cases where the pin was a bit too short, slipped out of the correct slot, and the engine was still starting and running somewhat normally.

Have you checked the fuel pressure?
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Old 01-11-2021, 10:16 PM
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Re: 1996 optispark, plug and wires replacing

If you don't have a fuel pressure gauge, do you hear the pump running when you turn the key but don't try to start it?
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Old 01-16-2021, 12:19 PM
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Re: 1996 optispark, plug and wires replacing

no gauge yet I do hear pump when turning key just short of start position
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Old 01-16-2021, 01:07 PM
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Re: 1996 optispark, plug and wires replacing

When you turn the key to the “RUN” position, the fuel pump should run for 2 seconds, and shut down. Should produce at least 40 PSI. Pressure should not bleed off quickly.

The pump will not restart when the starter is cranking the engine until: 1) the PASS-Key (VATS) system sends the “fuel enable” signal (50 Hz square wave from BCM) to the PCM, and 2) the PCM sees the low resolution cam position pulse signal from the optical sensor in the Opti.
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Old 04-22-2021, 11:59 AM
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Re: 1996 optispark, plug and wires replacing

please advise where valve is located to test fuel pressure, thought it was along drivers side of fuel rail. TZ
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Old 04-22-2021, 12:10 PM
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Re: 1996 optispark, plug and wires replacing

Courtesy of Rob...

http://shbox.com/1/fp_reg.jpg
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Old 04-23-2021, 01:22 AM
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Re: 1996 optispark, plug and wires replacing

thank you, know what size valve for testing?
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Old 04-23-2021, 10:24 AM
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Re: 1996 optispark, plug and wires replacing

Fitting is -4AN
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Old 04-25-2021, 02:51 PM
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Re: 1996 optispark, plug and wires replacing

OP,

I scanned this thread and don't see any error codes listed. Did you check for codes? Is the check engine light on? I learned (from Fred!) long ago not to try to diagnose these cars without a code reader.
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Old 05-29-2021, 06:14 PM
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Re: 1996 optispark, plug and wires replacing

tested pressure, spiked at 43 to 48 psi initially, held at 40 pounds, slowly bled off after five minutes pressure was down to 38 pounds
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Old 05-29-2021, 06:50 PM
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Re: 1996 optispark, plug and wires replacing

any tips on testing coil?
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Old 05-29-2021, 09:43 PM
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Re: 1996 optispark, plug and wires replacing

Continuity test:

http://shbox.com/1/coil_testing.jpg
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Old 05-30-2021, 10:01 AM
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Re: 1996 optispark, plug and wires replacing

thanks!

fuel pressure readings are okay?
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Old 05-30-2021, 11:10 AM
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Re: 1996 optispark, plug and wires replacing


different coil and meter from picture that was sent
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Old 05-30-2021, 12:30 PM
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Re: 1996 optispark, plug and wires replacing

Shoebox’s photo is a 94/95 coil with 2 connectors. Yours is a 96/97 coil with a single connector. Internally, the wiring is all the same. Just probe the 2 pins in your single connector the same way shown in the photo. The exact resistance isn’t important. You are just verifying there is no open circuit.

94/95:

http://shbox.com/1/95_ign_system_schematic.jpg

96/97:

http://shbox.com/1/1996_ec_03_ign_system.jpg

The photo was not intended to tell you that you had you had to use the same brand/type of meter. Your appears to be set on 25 Kohms, so that's all that matters.

Fuel pressure is OK.
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