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Discussion Starter #1
So I had the guy on ebay rebuild my opti last year, and it died after only like 10 months

"berrington1' is his name

He said the issue with my old opti was "the high resolution pulse was missing".....
Caused by "a failure of the optical sensor or the associated internal electronics"

He sent me a new one with no charge, however it cost me a lot of money to finally get the issue diagnosed correctly, and repaired, not to mention like 2 months of the car either in the shop, or me not driving it because i didn't want to drive it while it was screwed up

But I wont know if the NEW one is ok for God knows how long, (I had to put in a cheap one till "berrington1" could get the rebuilt one back to me because I couldn't be without a working car any longer smh)

So just buyer beware with that ebay guy....."berrington1"

Btw, what do you guys think would cause "the high resolution pulse to be missing/ failure of the optical sensor or the associated internal electronics" on the first optispark he did for me?

Isn't that something he should/could have spotted/fixed before he sent it back to me?....
I mean i only drove with the first one he sent me for like 10 months before it died

But now i got a even more serious issue....I have a low compression cylinder/valve (90 psi)

Do you think the opti going bad could have caused the valve compression issue?

It was NOT having this issue before the opti went out

How long do you think I can keep driving the car like this before it gives out?

It's a 94 caprice Lt1 9c1 with like roughly 90k-100k miles on it, and the car DRIVES great, but it idles pretty damn rough

Thanks
 

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I don't think a sensor failure is something he could have predicted, especially if it failed 10 months after installation. The opti doesn't have anything to do with valve or piston ring sealing.
 

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You provide a fair amount of background, but a couple things:

Did you have your original factory opti sent in and rebuilt, or was it an aftermarket he sent you? OEM optis are about the only ones ever to use the Mitsubishi optical sensor, which I have never heard as having failed or been the cause of an original opti going down. As long as the bearing holds out, the original unit will last with just expected periodic maintenance tune-up with cap, rotor, new seals and vent system service.

The sensors in about all aftermarket brands have been at least accused at one time or another of being less robust than Mitsubishi optical sensors (which are long NLA), with reports they don't hold up to heat or hot operating conditions (ex: go dead on the road and then work again when cooled down).

The vast majority of permanent total failure of aftermarket of most brands soon after installation has been found to be plain bad optical reader, poor quality parts, poor quality assembly, and overall failure to perform a full 'blueprinting' of the unit even brand new and before installation, with procedure laboriously detailed in several other threads. I'm going to default to this rebuilder being aware of these details, thus eliminating them as causes for your first failure.

+1 on NOT presuming that the rebuilder should have been able to predict a failure 10 months in the making. Without any more to go on I'm actually thinking better of the rebuilder after having sent you a replacement no charge. He can't be held responsible for however well or how long a shop takes to diagnose and fix and charge for the work. For those not doing their own wrenching on this very short-lived LT1 era there's diminishing-to-nonexistent mechanics with the experience, - which translates into painful repair costs and too often less than stellar outcomes.

And without more to go on, there's other issues that may be the cause of reader failure. The harness has been attributed with opti failures as well, and you didn't mention whether it was replaced with the initial installation, or whether with the replacement, or still original (which would eliminate it as the culprit).

Glad to hear you're back running. There's numerous fuel, vacuum, ignition and emissions related issues treated by either maintenance or diagnostic testing for a rough idle condition that is either masked or lessened at higher revs.
 

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The basic question is should a rebuilder be able to predict that a part that may be 26 years old and in a hostile heat cycling location fail after he has checked it? I could not hold someone to warranty a old customer owned part.

A shop can check the high resolution pulses with a scope. (just like the rebuilder did) A cylinder balance test would have suggested a low compression cylinder. I understand Ehack can do a balance test or a mechanic can just disable one sparkplug at a time or one fuel injector.

With a live data scanner and a scope a high resolution problem can be diagnosed. If it was intermittent it can be hard and take time. Your cylinder problem could have been diagnosed with a rpm gauge and a little work.

I watched a utube where a mehchanic ran a car for a week to get it to present a problem. The owner had spent thousands at other shops that could not find the cause. Was this the shop's fault or the car's manufacturer's?
 

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OP

IMHO the ebay guy did all he could in sending you a part that was working when he serviced the opti. The opti issue is separate from your low , and serious, compression issue. The only fix for that is a rebuild assuming a valve associated with that cyl is not hanging open causing the low compression. If the valve was the issue than pulling the heads and getting a valve job would resolve it

having a 25 year old car as your DD has it challenges if you do not work on it yourself as finding qualified service let alone paying for it is the problem.

there are 100's of thousands of 95-97 LT1 cars in the junkyards. Finding an original AC delco opti seems to be the only solution to either getting one that works or at least harvesting the Mitsubishi sensor to put in a aftermarket clone opti. Unfortunately indexing the wheel on the clones seems to be the chronic fail on those so rebuilding a "original" AC Delco like the ebay guy does seems to be the only "better" solution for any Opti replacement
 

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It's getting darned near impossible to find a JY tri-9 B- D- F- without the opti stripped out. It might even be one of them things the workers there learn to ebay for pocket change. Like pristine Fleetwood skirts, reverse lights, front fender extensions. '96 center console and brackets.
 

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I have 2 OEM AC Delco opti. One was replaced at 50K on my car after a misdiagnosis - it was the coil. This forum taught me that. Bought new one from Dal and kept the original. Other was bought as a spare when it became evident 15 years ago that optis were a big deal. As noted the sensor is the key. Let me dig them out and retest. They are clean San Diego parts but may need new "O" rings on shaft.

Marked (dot etched) p/n 1104032 the correct GM part with Mitsubishi sensor.
 

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Discussion Starter #8 (Edited)
You provide a fair amount of background, but a couple things:

Did you have your original factory opti sent in and rebuilt, or was it an aftermarket he sent you? OEM optis are about the only ones ever to use the Mitsubishi optical sensor, which I have never heard as having failed or been the cause of an original opti going down. As long as the bearing holds out, the original unit will last with just expected periodic maintenance tune-up with cap, rotor, new seals and vent system service.

The sensors in about all aftermarket brands have been at least accused at one time or another of being less robust than Mitsubishi optical sensors (which are long NLA), with reports they don't hold up to heat or hot operating conditions (ex: go dead on the road and then work again when cooled down).

The vast majority of permanent total failure of aftermarket of most brands soon after installation has been found to be plain bad optical reader, poor quality parts, poor quality assembly, and overall failure to perform a full 'blueprinting' of the unit even brand new and before installation, with procedure laboriously detailed in several other threads. I'm going to default to this rebuilder being aware of these details, thus eliminating them as causes for your first failure.

+1 on NOT presuming that the rebuilder should have been able to predict a failure 10 months in the making. Without any more to go on I'm actually thinking better of the rebuilder after having sent you a replacement no charge. He can't be held responsible for however well or how long a shop takes to diagnose and fix and charge for the work. For those not doing their own wrenching on this very short-lived LT1 era there's diminishing-to-nonexistent mechanics with the experience, - which translates into painful repair costs and too often less than stellar outcomes.

And without more to go on, there's other issues that may be the cause of reader failure. The harness has been attributed with opti failures as well, and you didn't mention whether it was replaced with the initial installation, or whether with the replacement, or still original (which would eliminate it as the culprit).

Glad to hear you're back running. There's numerous fuel, vacuum, ignition and emissions related issues treated by either maintenance or diagnostic testing for a rough idle condition that is either masked or lessened at higher revs.
The first one he did for me was my original OEM opti
(the one that failed)

The second one that he sent me is also an OEM (with the Mitusbishi lens)

I currently have an aftermarket one in the car now, so the one he sent me is just going to sit in the closet i guess, until I can afford to buy a 96 caprice or impala sometime in the distant future and install it on that
(a 96 is my ultimate car goal)

Im not sure what you mean by "reader failure", and the "harness"

Can you explain more about the "harness" please?

So you're also saying you think its possible that the rough/bad idle could be something else other than the low compression cylinder?

I do know for sure the compression read 90psi on the cylinder....
(we checked it twice and i saw the gauge with my own eyes)

We also cranked the camshaft manually to observe the movement of the valves, and they were not in sync the way they should be.....
 

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Discussion Starter #9
I have 2 OEM AC Delco opti. One was replaced at 50K on my car after a misdiagnosis - it was the coil. This forum taught me that. Bought new one from Dal and kept the original. Other was bought as a spare when it became evident 15 years ago that optis were a big deal. As noted the sensor is the key. Let me dig them out and retest. They are clean San Diego parts but may need new "O" rings on shaft.

Marked (dot etched) p/n 1104032 the correct GM part with Mitsubishi sensor.
Ok, are you going to test to see if they have the same issue mine had?
 

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Discussion Starter #10 (Edited)
OP

IMHO the ebay guy did all he could in sending you a part that was working when he serviced the opti. The opti issue is separate from your low , and serious, compression issue. The only fix for that is a rebuild assuming a valve associated with that cyl is not hanging open causing the low compression. If the valve was the issue than pulling the heads and getting a valve job would resolve it

having a 25 year old car as your DD has it challenges if you do not work on it yourself as finding qualified service let alone paying for it is the problem.

there are 100's of thousands of 95-97 LT1 cars in the junkyards. Finding an original AC delco opti seems to be the only solution to either getting one that works or at least harvesting the Mitsubishi sensor to put in a aftermarket clone opti. Unfortunately indexing the wheel on the clones seems to be the chronic fail on those so rebuilding a "original" AC Delco like the ebay guy does seems to be the only "better" solution for any Opti replacement
Yeah I just always assumed that regardless of the type of car, the older they are then the more simple they are to diagnose, and repair for any mechanic lol


Ok, well it sounds like you guys are saying the ebay guy wasn't halfstepping the work and did all he could....that's what i wanted to know


So you think a valve hanging open could be the cause instead of the valve being straight up shot?


A mechanic told me a doing a valve job might be a bad idea because after getting it done it would then leave me with a much weaker bottom end of the engine, thus possibly causing more issues


You agree with that?
 

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Discussion Starter #11
I don't think a sensor failure is something he could have predicted, especially if it failed 10 months after installation. The opti doesn't have anything to do with valve or piston ring sealing.
Ok thanks
 

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Discussion Starter #12
The basic question is should a rebuilder be able to predict that a part that may be 26 years old and in a hostile heat cycling location fail after he has checked it? I could not hold someone to warranty a old customer owned part.

A shop can check the high resolution pulses with a scope. (just like the rebuilder did) A cylinder balance test would have suggested a low compression cylinder. I understand Ehack can do a balance test or a mechanic can just disable one sparkplug at a time or one fuel injector.

With a live data scanner and a scope a high resolution problem can be diagnosed. If it was intermittent it can be hard and take time. Your cylinder problem could have been diagnosed with a rpm gauge and a little work.

I watched a utube where a mehchanic ran a car for a week to get it to present a problem. The owner had spent thousands at other shops that could not find the cause. Was this the shop's fault or the car's manufacturer's?
Yeah we disabled one sparkplug at a time, then after we narrowed down the problem cylinder we removed the sparkplug, and then tested the compression twice.....it read 90psi

Then we manually cranked the camshaft to observe the motion/movement of the valves on that cylinder and the valves were not moving as they should
 

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The first one he did for me was my original OEM opti
(the one that failed)

The second one that he sent me is also an OEM (with the Mitusbishi lens)

I currently have an aftermarket one in the car now, so the one he sent me is just going to sit in the closet i guess, until I can afford to buy a 96 caprice or impala sometime in the distant future and install it on that
(a 96 is my ultimate car goal)

Im not sure what you mean by "reader failure", and the "harness"

Can you explain more about the "harness" please?

So you're also saying you think its possible that the rough/bad idle could be something else other than the low compression cylinder?

I do know for sure the compression read 90psi on the cylinder....
(we checked it twice and i saw the gauge with my own eyes)

We also cranked the camshaft manually to observe the movement of the valves, and they were not in sync the way they should be.....
The harness referenced is installed in the top of the opti. It comes from the pass side of the main harness. In a high heat area, often corroded, and the release tab is easily broken. There is also a vacuum harness from the bottom of the opti to the drivers side intake (2 blue in line filters). Both are critical to proper opti operation. Easily replaced and available.
 

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The first one he did for me was my original OEM opti
(the one that failed)

The second one that he sent me is also an OEM (with the Mitusbishi lens)

I currently have an aftermarket one in the car now, so the one he sent me is just going to sit in the closet i guess, until I can afford to buy a 96 caprice or impala sometime in the distant future and install it on that
(a 96 is my ultimate car goal)

......

Can you explain more about the "harness" please?

So you're also saying you think its possible that the rough/bad idle could be something else other than the low compression cylinder?

.........
1. When the aftermarket replacement was installed, did you get back that original oem one you had rebuilt? It may or may not have 'failed'. There are numerous ways to install an opti incorrectly, and only one way to install one correctly. Any issues with leaking seals (either the ones in the timing case or those on the opti itself) can have fluids messing with signals. If (hopefully) you still have it then you can inspect for that, as well as anything inside that became loose. Most rebuilders would know not to use cheap/weak tune-up parts, and to locktite everything.

2. Grandpas- covered the harness. At very least it needs dielectric grease, but just best to replace it new when changing the opti.

3. Repeating, There's many separate fuel, vacuum, ignition and emissions related issues that result in a miss. Anything NOT dealt with by both scheduled maint. and close visual inspection is suspect. There's stickies in different topics on miss issues. Ex: Air - countless potential locations for vacuum leaks and all 25-year old hoses are long overdo to replace. Intake manifold china walls. Broken ex. man. studs throwing off fuel mixture. MAP grommit, dirty MAF...... Reapeat for fuel system issues. Repeat for ignition. Replace all wires and plugs. Test, or better yet just replace the 1/4-century old coil and ICM. For emissions there's the EVAP system hoses (all the way to the tank), the solenoid, and all the hoses to the canister. A broke/stuck EGR might have some affect on idle IDR.

It sounds like you're one up on the deal. At very least (and not already done) you should send back your first rebuilt unit for the rebuilder to track down the failure issue, and then you'll both know.
 

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It sounds like you're one up on the deal. At very least (and not already done) you should send back your first rebuilt unit for the rebuilder to track down the failure issue, and then you'll both know.

He said the issue with my old opti was "the high resolution pulse was missing".....
Caused by "a failure of the optical sensor or the associated internal electronics"

He sent me a new one with no charge,
The OP had a bad sensor and hopefully got a good one. I guess the vendor is trying his best. I wish other vendors could post the number of tested bad/good returns they get. Unfortunately I expect some good ones are written off.

There are numerous ways to install an opti incorrectly, and only one way to install one correctly. Any issues with leaking seals (either the ones in the timing case or those on the opti itself) can have fluids messing with signals.
I have always wondered how many good OPTI venders have gotten out of the business due to "part swapers" blaming the vendor's OPTI for mechanical engine problems or bad wiring. I have been playing with a new harness idea that uses new larger gauge wire from the OPTI all the way to the PCM pins. The OPTI is a low level signal and new better wire may be the cure for some cars. The original wire might meet automotive engineering standards but I personally think it is too thin, and am willing to try twisting the signal wires and adding a grounded wire shield. This is overkill but OPTI issues can be hard to sort out.
 

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I caught the code being thrown, but was being lenient with our ancient ecm for possibly lumping together different end states with multiple causes. Instead of an totally 'missing' something connoting a fubared sensor, could it also be sourced to oil flinging around and messing with the signal, loose slotted wheel causing count errors, and/or notorious hardened-cracked-undersized wires everywhere breaking the counts? Like I mentioned, this'll be the official first time I ever heard of a broke Mitsubishi.

And I didn't want to add to confusion, but read at least twice in the past that a weak or 'crapping out when hot' IC - ICM can either disrupt signal or outright burn up the opti.
 

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So you think a valve hanging open could be the cause instead of the valve being straight up shot?


A mechanic told me a doing a valve job might be a bad idea because after getting it done it would then leave me with a much weaker bottom end of the engine, thus possibly causing more issues


You agree with that?
a valve job will not impact the bottom end other than "stopping" low compression on the particular cylinder...which is a good thing as otherwise carbon buildup is occurring on that piston from unburnt fuel.

You need to confirm a valve is actually "hanging open" by doing a leak down test....low compression can, and often is, bad rings
 

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I have been playing with a new harness idea that uses new larger gauge wire from the OPTI all the way to the PCM pins. The OPTI is a low level signal and new better wire may be the cure for some cars. The original wire might meet automotive engineering standards but I personally think it is too thin, and am willing to try twisting the signal wires and adding a grounded wire shield. This is overkill but OPTI issues can be hard to sort out.
Gary @ Innovative Wiring has been making "better" opti harness for years. I have been using one for several years

 

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There is no doubt I would want one of Gary's products over any mass produced part. A mass produced part with cheap contacts may be as bad as the old 26 year old part.

But what I said was:
from the OPTI all the way to the PCM pins.

The replaceable section is only a small part of the wiring between the OPTI and the PCM.
 

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Discussion Starter #20
1. When the aftermarket replacement was installed, did you get back that original oem one you had rebuilt? It may or may not have 'failed'. There are numerous ways to install an opti incorrectly, and only one way to install one correctly. Any issues with leaking seals (either the ones in the timing case or those on the opti itself) can have fluids messing with signals. If (hopefully) you still have it then you can inspect for that, as well as anything inside that became loose. Most rebuilders would know not to use cheap/weak tune-up parts, and to locktite everything.

2. Grandpas- covered the harness. At very least it needs dielectric grease, but just best to replace it new when changing the opti.

3. Repeating, There's many separate fuel, vacuum, ignition and emissions related issues that result in a miss. Anything NOT dealt with by both scheduled maint. and close visual inspection is suspect. There's stickies in different topics on miss issues. Ex: Air - countless potential locations for vacuum leaks and all 25-year old hoses are long overdo to replace. Intake manifold china walls. Broken ex. man. studs throwing off fuel mixture. MAP grommit, dirty MAF...... Reapeat for fuel system issues. Repeat for ignition. Replace all wires and plugs. Test, or better yet just replace the 1/4-century old coil and ICM. For emissions there's the EVAP system hoses (all the way to the tank), the solenoid, and all the hoses to the canister. A broke/stuck EGR might have some affect on idle IDR.

It sounds like you're one up on the deal. At very least (and not already done) you should send back your first rebuilt unit for the rebuilder to track down the failure issue, and then you'll both know.
1. When the aftermarket replacement was installed, did you get back that original oem one you had rebuilt? It may or may not have 'failed'. There are numerous ways to install an opti incorrectly, and only one way to install one correctly. Any issues with leaking seals (either the ones in the timing case or those on the opti itself) can have fluids messing with signals. If (hopefully) you still have it then you can inspect for that, as well as anything inside that became loose. Most rebuilders would know not to use cheap/weak tune-up parts, and to locktite everything.

2. Grandpas- covered the harness. At very least it needs dielectric grease, but just best to replace it new when changing the opti.

3. Repeating, There's many separate fuel, vacuum, ignition and emissions related issues that result in a miss. Anything NOT dealt with by both scheduled maint. and close visual inspection is suspect. There's stickies in different topics on miss issues. Ex: Air - countless potential locations for vacuum leaks and all 25-year old hoses are long overdo to replace. Intake manifold china walls. Broken ex. man. studs throwing off fuel mixture. MAP grommit, dirty MAF...... Reapeat for fuel system issues. Repeat for ignition. Replace all wires and plugs. Test, or better yet just replace the 1/4-century old coil and ICM. For emissions there's the EVAP system hoses (all the way to the tank), the solenoid, and all the hoses to the canister. A broke/stuck EGR might have some affect on idle IDR.

It sounds like you're one up on the deal. At very least (and not already done) you should send back your first rebuilt unit for the rebuilder to track down the failure issue, and then you'll both know.
Yes, they returned the bad opti back to me when they installed the aftermarket one

I then returned it back to the ebay guy and he sent me a "fresh rebuilt OEM opti"

That's what he said anyways

And after he inspected the failed one i sent back he said the issue with my old opti was:
"The high resolution pulse was missing".....caused by "a failure of the optical sensor or the associated internal electronics"

As far as my miss issue....we tested the compression and checked the valves manually and it said 90psi and the valves were out of sync when we manually cranked the camshaft

Im a little confused, are you saying that might not be my issue?
 
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