Re: 1993 LT1 Intermittent Crank-No Start
Good news. I finished replacing the opti-spark distributor, and the car now runs great! I want to share some lessons learned from a car guy who has never worked on a computer controlled car before:
Take the time to diagnose the problem.
Instead of guessing why the car doesn’t start or throwing parts at it, use the diagnostic flowcharts in the service manual. If you can read a flowchart and a schematic, then you can figure out a C4. If you intend to own your C4 awhile, consider investing in a Tech 2. I recommend a new Tech 2 clone (see earlier post); they cost less than $400 and will save time and guesswork.
Leverage this community.
A big shout out and thank you to Edward Johnson and Dave Perry. They took the time to talk me through several questions while diagnosing the problem.
Replacing an Opti-spark distributor isn’t difficult.
Yes, it takes several hours and you need to remove a lot more stuff to get to it than any other distributor I know. But the process isn’t hard if you have wrenching skills. As a comparison for you C3 guys, Opti-spark R&R takes less time than replacing a radiator on a C3 big block with AC.
Expect scope creep.
This is a good opportunity to replace spark plugs, cables, water pump, thermostat, serpentine belt and flush the cooling system. I almost replaced hoses too, but they looked and felt fine. Replacing spark plug cables is much easier if the AC compressor is moved aside (four 10mm bolts), the ASR is moved aside (three 10mm bolts), the belt tensioner is removed (one bolt), and radiator hoses are disconnected (already done to R&R the distributor). Oh, know that changing the #8 spark plug lengthened total project time 20%. Let me know if you have a trick for this.
No need to raise the engine.
The procedure for distributor R&R in the service manual includes disconnecting the motor mounts and raising the engine a few inches to remove the harmonic balancer. That’s not necessary. The balancer can be unbolted and moved out of the way without moving the engine.
Replace seals.
Replace the distributor and water pump shaft seals to prevent leaks. It’s easy to install these improperly so do your homework about this.
And thank all of you for your support and help!
Good news. I finished replacing the opti-spark distributor, and the car now runs great! I want to share some lessons learned from a car guy who has never worked on a computer controlled car before:
Take the time to diagnose the problem.
Instead of guessing why the car doesn’t start or throwing parts at it, use the diagnostic flowcharts in the service manual. If you can read a flowchart and a schematic, then you can figure out a C4. If you intend to own your C4 awhile, consider investing in a Tech 2. I recommend a new Tech 2 clone (see earlier post); they cost less than $400 and will save time and guesswork.
Leverage this community.
A big shout out and thank you to Edward Johnson and Dave Perry. They took the time to talk me through several questions while diagnosing the problem.
Replacing an Opti-spark distributor isn’t difficult.
Yes, it takes several hours and you need to remove a lot more stuff to get to it than any other distributor I know. But the process isn’t hard if you have wrenching skills. As a comparison for you C3 guys, Opti-spark R&R takes less time than replacing a radiator on a C3 big block with AC.
Expect scope creep.
This is a good opportunity to replace spark plugs, cables, water pump, thermostat, serpentine belt and flush the cooling system. I almost replaced hoses too, but they looked and felt fine. Replacing spark plug cables is much easier if the AC compressor is moved aside (four 10mm bolts), the ASR is moved aside (three 10mm bolts), the belt tensioner is removed (one bolt), and radiator hoses are disconnected (already done to R&R the distributor). Oh, know that changing the #8 spark plug lengthened total project time 20%. Let me know if you have a trick for this.
No need to raise the engine.
The procedure for distributor R&R in the service manual includes disconnecting the motor mounts and raising the engine a few inches to remove the harmonic balancer. That’s not necessary. The balancer can be unbolted and moved out of the way without moving the engine.
Replace seals.
Replace the distributor and water pump shaft seals to prevent leaks. It’s easy to install these improperly so do your homework about this.
And thank all of you for your support and help!
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