Another Opti Help Request
Another Opti Help Request Hope for some help or confirmation.
While on the track last weekend car had a brief stutter and then engine stopped running.
Once in the pits found that the radiator sprung a leak and the front of the engine was dripping wet. No water went above the throttle body and no water anywhere near the PCM
Here is where I am testingwise:
1. Fuel to rail. I used the Fuel Pump Prime pigtail near the PCM to make sure.
2. No spark at coil while cranking.
3 Tested Ignition Control Module 4 pin as follows:
A = Battery Voltage (12.4) (Consistent with Shop Manual)
B = Manual says 1vac-4vac while cranking. I tried this and got 0 on the meter when the ground lead from the meter was held on a ground.
BUT when I tapped the ground lead on the ground voltage showed up.
C = 0 ohms to ground with key OFF (Consistent with Shop Manual)
D = Battery Voltage (12.4) (Consistent with Shop Manual)
Tested the 4 pin from the opti with the key ON except for D as follows:
A = .25 vdc (Manual says ~5vdc)
B = .25 vdc (Manual says ~5vdc)
C = 12.4 (Consistent with Manual)
D = 0 ohms with key OFF (Consistent with Manual)
No spark at coil tells me that the ICM could be bad except I am concerned about the Pin B test result because this voltage comes from the PCM. If I am getting the correct voltage at Pin B, then PCM is working and Opti is probably the problem, if not is there a problem with the PCM?
However, I am most concerned about the Opti 4 pin test for pins A & B. The DC voltage is significantly lower than the 5vdc that should be coming from the PCM.
Any help with this would be greatly appreciated.
While on the track last weekend car had a brief stutter and then engine stopped running.
Once in the pits found that the radiator sprung a leak and the front of the engine was dripping wet. No water went above the throttle body and no water anywhere near the PCM
Here is where I am testingwise:
1. Fuel to rail. I used the Fuel Pump Prime pigtail near the PCM to make sure.
2. No spark at coil while cranking.
3 Tested Ignition Control Module 4 pin as follows:
A = Battery Voltage (12.4) (Consistent with Shop Manual)
B = Manual says 1vac-4vac while cranking. I tried this and got 0 on the meter when the ground lead from the meter was held on a ground.
BUT when I tapped the ground lead on the ground voltage showed up.
C = 0 ohms to ground with key OFF (Consistent with Shop Manual)
D = Battery Voltage (12.4) (Consistent with Shop Manual)
Tested the 4 pin from the opti with the key ON except for D as follows:
A = .25 vdc (Manual says ~5vdc)
B = .25 vdc (Manual says ~5vdc)
C = 12.4 (Consistent with Manual)
D = 0 ohms with key OFF (Consistent with Manual)
No spark at coil tells me that the ICM could be bad except I am concerned about the Pin B test result because this voltage comes from the PCM. If I am getting the correct voltage at Pin B, then PCM is working and Opti is probably the problem, if not is there a problem with the PCM?
However, I am most concerned about the Opti 4 pin test for pins A & B. The DC voltage is significantly lower than the 5vdc that should be coming from the PCM.
Any help with this would be greatly appreciated.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
front engine wet, car stops running...screams Opti got soaked.
remove Opti and take C&R off then carefully clean inside. Use a paper towel, flat, pull through optical solt as it likely got coolant inside it.
Use blue loc-tite on rotor screws and skim coat of dialectic grease on large cap O ring to help seal it.
If opti is a real AC Delco, never get rid of it. If cap and rotor are worn, like any dizzy its a wear item, replace with a Standard Motor Products one from Rockauto (brass terminals)
remove Opti and take C&R off then carefully clean inside. Use a paper towel, flat, pull through optical solt as it likely got coolant inside it.
Use blue loc-tite on rotor screws and skim coat of dialectic grease on large cap O ring to help seal it.
If opti is a real AC Delco, never get rid of it. If cap and rotor are worn, like any dizzy its a wear item, replace with a Standard Motor Products one from Rockauto (brass terminals)
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
If there is a way to test the optical sensor itself, IDK.
It takes very little oil or coolant to contaminate the sensor so it can't "see".
You will have to take off the index wheel and carefully clean the sensor and any visible signs of fluid. Take note on how it is indexed, make a pen mark on it and body if needed
Another opti fail reason is the rotor screws come out so rotor just spins. The screws would be inside Opti. Just put them back on with loc-tite
It takes very little oil or coolant to contaminate the sensor so it can't "see".
You will have to take off the index wheel and carefully clean the sensor and any visible signs of fluid. Take note on how it is indexed, make a pen mark on it and body if needed
Another opti fail reason is the rotor screws come out so rotor just spins. The screws would be inside Opti. Just put them back on with loc-tite
OK . . . . . I get the DUMB *** of the year award.
Last night I went to the pin out diagrams for the PCM to trace the B+ connections that power the PCM. I found 4. 2 that get power from the fuse box (#4 & #5) in the car and 2 that get power from the fuse box under the hood (#11).
I went to the diagram of the fuse box in the car that I had from the same manual, and looked at the #4 & #5 fuse. Diagram says #5 ignition, #4 RADIO ACCY!!!! When I originally checked the fuses I looked at #5 and #11 and both were good.
#4 was blown. New fuse, fired right up. Water probably got on something and caused a short. Everything is dry now.
Last night I went to the pin out diagrams for the PCM to trace the B+ connections that power the PCM. I found 4. 2 that get power from the fuse box (#4 & #5) in the car and 2 that get power from the fuse box under the hood (#11).
I went to the diagram of the fuse box in the car that I had from the same manual, and looked at the #4 & #5 fuse. Diagram says #5 ignition, #4 RADIO ACCY!!!! When I originally checked the fuses I looked at #5 and #11 and both were good.
#4 was blown. New fuse, fired right up. Water probably got on something and caused a short. Everything is dry now.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
its always the little stuff.
My 67 Camaro has the old glass tube fuses. IGN is 10 amps. Coil is 8 amp load so no issue....but adding Pertronix module, 3 amps, and EL choke, 1amp.....well "eventually" it blew the 10 amp. Initially I was checking distributor until I had the brain fart to check fuse.
So if you are ever adding stuff to IGN circuit so you have +12v with key on, engine running, it all adds up. As long as different wires are used to feed whatever added than just go up in fuse amp capability. Just don't exceed the amp ability of any single gauge wire feeding IGN power at fuse block.
My 67 Camaro has the old glass tube fuses. IGN is 10 amps. Coil is 8 amp load so no issue....but adding Pertronix module, 3 amps, and EL choke, 1amp.....well "eventually" it blew the 10 amp. Initially I was checking distributor until I had the brain fart to check fuse.
So if you are ever adding stuff to IGN circuit so you have +12v with key on, engine running, it all adds up. As long as different wires are used to feed whatever added than just go up in fuse amp capability. Just don't exceed the amp ability of any single gauge wire feeding IGN power at fuse block.
Trending Topics
Launching!
Joined: Mar 2022
Posts: 247
Likes: 32
If you have a laptop and a data logger program or scanning program. If you connect into to the OBD1 connecter and try starting the car, if you see the injector pulse width is zero then its your optispark. Its what I found to be consistent when my opti died four times in less than 10k miles.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo