LT1-LT4 Modifications 1993-97 Gen II Small Block V8

F#ck Optis...

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Old 11-04-2011, 10:28 PM
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I was going to go LS but then some things came up and i was a good ways away from being done and i had already spent a LOT of cash and in the end had to sell it. So now im going to the next best thing IMO.
Old 11-04-2011, 10:29 PM
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Originally Posted by Paul Bell
You guys might discover the cheep new coils that end up on ebay for 20 bucks were rejected by GM. These rejects then get dumped to the surplus market and eventually make their way to ebay.

Go buy a 50 cent light bulb at Pep Boys. Go home. Submit the online survey. Print out the 10% coupon. Go back to Pep Boys and buy new boxed coils-with a warranty. Use your 10% coupon.
Well mine were pulled from a 5.3 by a friend that gave me the friend deal.
Old 11-04-2011, 10:31 PM
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Originally Posted by lethal bird
Well mine were pulled from a 5.3 by a friend that gave me the friend deal.
Yes, pulled from an engine is always a good deal.
Old 11-04-2011, 10:59 PM
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I bought my ls6 coils with harness for 150.00 and I paid 260.00 for a brand new LTCC conversion off ebay..I have a MSD opti and its only purpose is cam position...The motor runs alot smoother and throttle is crisp..Well worth the money..If anyone needs a 92-94 GM opti with a MSD cap and rotor,only used for 500 miles.I am selling for 250.00 shipped,including pp fees.
Old 12-28-2011, 10:07 PM
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Originally Posted by Paul Bell
The opti pickup and window wheel is actually a good and reliable component-and it's a relatively precision device. It's the rotor and all the high voltage flying around in there that screws things up. Add some moisture/water to the mix and you're hood up on the side of the road.

Moving to the LTCC system is the next step up in reliability-and it definitely helps engine response. It's the only thing that made my '94 a daily driver.

Of course, if I had a LT1 car and had to do it all over today, the EFI24x system would be number one on my to do list.

If you go with the LTCC system, specify LS2 coil plugs and use LS2 coils, they out perform the LS1 coils. You cannot use the round heat-sinked truck coils with the LTCC system.

And yes, the MSD LS coils are crap.
Do you know why you can't use the truck coils? I was just thinking today bout using the ones off my 5.3 motor and doin the ltcc setup. I want the 24x but i have to get newer style transmission too
Old 12-28-2011, 10:12 PM
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Good question. They seemed to be way advanced. The engine definitely had more power but under part to mid throttle the engine pinged quite a bit.

The heat sinked truck coils are a very different animal than any of the other coils.
Old 12-28-2011, 11:20 PM
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Originally Posted by Paul Bell
The heat sinked truck coils are a very different animal than any of the other coils.
Which is why there the coils im going to run with my 24x!
Old 12-29-2011, 01:55 AM
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Have vented ones on two LT1 cars and haven't had any crazy issues with them at all. Even with lots of 7000pm shifts. Thought I had a catastrophic opti problem a few times, but after diagnosing more thoroughly it always ended up being something else.

Changed a cap and rotor once on a 140,000 mile 15 year old opti, that's it.



-Dustin-
Old 12-29-2011, 05:03 AM
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Opti's get a bad wrap, install it correctly, maintaince it (re: make sure the water pump isnt dumping on it). Not reading through 3 pages of this bad opti thread and sure its been mentioned, but 3 opti's is a sure sign of something else wrong. Id get serious about checking your wiring harness, etc. for bad connections. The wiring in these cars isnt even nearly protected enough...

Im saying this while my car is down cause the opti went out Dynaspark installed and chasing wiring issues in my own car. Ive had my LT1 car about 5-6 years, 2 motors, 3 transmissions, 2 rearends, and my 3rd opti...fun fun.
Old 12-29-2011, 06:19 AM
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Originally Posted by the_merv
I never had an Opti issue with the LT1 I had..one of them things I guess..
I had a car with 120k on the original opti...changed it when I did a head gasket for good measure. My new TA had it replaced at 60k...I think the dealership just hosed the original owner, so I have no idea if it really needed it. My brother had issues with his around 120k and changed it with a delphi unit. So far he is having no issues either.

My biggest complaint with the opti is how damn hard it is to do anything to them. Even plug wires are a major PITA. After owning an ls1 car for 2 years I am spoiled.
Old 12-29-2011, 08:14 AM
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I guess I dont have the opti hate that many others here do.

Changed mine once, wasnt that big of a deal.


At this point, I dont think I could do a 24x conversion.

A 5.3 LS swap would be just a much better route IMO. I bet it would almost be similar in cost assuming I sold all of my LT1 stuff.
Old 12-29-2011, 08:39 AM
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Wow all of the opti hating is cracking me up.

The opti is an excellent distributor and does everything it should for most of us and can last a long time PROVIDED you know and address its quirks properly.

As already mentioned, genuine GM opti is the only way to go. I purchased the Accell opti years ago cause it was on sale for $100 and I just wanted to go through it and give it a chance. After disassembling it, the only issue I saw was the 360 degree segmented wheel, a few of the window openings were not very crisp plust the wheel was warped enough that it contacted the optical sensor. The other major issue with it was found after i installed it, there were sparks shooting out of the cap and into the nearby water pump. Clearly the high voltage pats in the cap were not insulated enough to prevent arcing. I quickly concluded Accell opti is junk and I will speculate that the other aftermarket optis (excluding MSD and the other expensive one that is not coming to mind at the moment) are **** as well.

Here are the tips to long opti life.
1. First and foremost, as already mentioned, get a genuine GM opti and convert to vented if your 93 or 94 LT1.

2. As soon as you remove the opti from the box, remove the four funky Torx screws and remove the cap. Remove the two screws and the plastic rotor then remove the metal shield. Now closely inspect the 360 degree segmented wheel for crisp cut windows and flatness. If any of the windows are rough meaning not crisply laser cut or the wheel contacts the sensor when spinning (meaning its warped), return it for another one or cannibalize an old opti for a known good segmented wheel and install it in the new unit. Lastly you want the segmented wheel to ride in the dead center of the sensors mouth as much as possible. This can be adjusted by adding or removing shims provided with the new opti or again cannibalizing them from an old one.

3. Inspect the mouth of the optical sensor and ensure there is no debris or plastic flashing in it, just look at it closely blow it out with air. BTW there is nothing magical about this sensor, all it is is two pairs of LED bulbs that detect pulses from the segmented wheel and send signals to the PCM, thats all. Lastly ensure the insides of the opti are free of dust and debris.

4. Inspect the large round seals on the inner plastic case. If they are not glued into place, this is likely not a genuine GM opti. Ensure the seals look uniform and properly installed.

5. When re-installing the plastic rotor, make sure the screws are loctited and DO NOT over tighten them or the rotor will break apart during use. I use red loctite and have never had an issue removing the screws when the need arises.

6. Inspect the oval rubber seal found on the 4 wire opti connector that plugs into the top of the opti. This seal must be uniform looking and greased with dielectric grease to ensure water and moisture does not enter the opti. This thing should be replaced every year since it can be done in less than 10 minutes.

7. Check the opti for air-tight sealing to keep contaminates out. Hook a mighty vac up to the outlet vent port that normally goes to the intake, plug the vent port normally running to the intake elbow and hold your finger over the large oval opening leading to the sensor. Pump the mighty vac up and if its sealing up tight. If it is, the needle will remain steady which indicates a good sealing opti. If the needle drops, it is not sealed and wherever the leak is you can expect contaminates to eventually enter the opti. Better find and address that leak or problems are in you future.

8. Inspect the connector contacts on the 4 wire harness leading to the sensor for corrosion and clean and re-grease if needed.

IMO when excessive moisture and water that can cause a running issue gets into the opti, it normally gets in at this oval seal in the opti connector on the top of the unit. Over time, this seal will shrink and harden to the point it can no longer seal out the moisture and then you have problems. I have bought replacement seals as part of connector kits on ebay plus they can be found as part of a complete generic replacement connector at any parts house, you just need to swap it from the new connector to the one on the car. IMO its this connector design and the way it installs through the middle case and into the optical sensor, that is the biggest engineering mistake in the opti aside from the knuckleheads not loctiting the rotor screws. I do think the round seals on the inner case do a very good job keeping water and moisture out and I see little value to RTV the seams although I guess it really cant hurt.

The opti is a rather simple yet well performing unit overall and just gets a bad rap IMO in most situations. Like I said you simply need to know how to address its quirks if you are to coexist with it and not hate your car.

7) check the opti for tight sealing to keep contaminates out. Hook a mighty vac up to the vent port that normally goes to the intake, plug the vent port normally running to the intake elbow and hold your finger over the large oval opening leading to the sensor. Pump the mighty vac up and if its sealing tight, the needle will remain steady which indicates a good sealing opti. If the needle drops, it is not sealed and wherever the leak is you can expect contaminates to eventually enter the opti. Better find and address that leak.

Some information before blaming the optical sensor. SES code 16 (low res) and 36 (high res) codes mean the optical sensor detected a bad reading from the segmented wheel (likely moisture or other contaminant in the opti) or there is a intermittent open circuit in the opti harness to the PCM (likely corrosion at the connectors). Like I mentioned above, I have seen warped segmented wheels wear away at the sensor and ultimately cause it to fail and I really believe this happens much more today than in the past. Again the optical sensor is nothing more than 2 pairs of LEDs in a plastic housing and the likelihood of a previously working sensor just up and failing, is very low. Dont believe me, grab a multimeter and perform a diode check on the LEDs if you suspect electrical failure for correct operation.

I suggest anyone considering on dropping huge coin for 24X to try the tips I provided on their current opti first before dishing out the money especially if money is really tight. Yes the 24X is awesome and if it were given to me, I would use it in a second, but then again I never have opti issues.

Lastly I see the opti as being part of the LT1s unique DNA and heritage. That said I dont mind jumping through a few hoops on occasion to preserve it.

Last edited by wrd1972; 01-07-2012 at 07:59 AM.
Old 12-29-2011, 08:47 AM
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^ words to live by!
Old 12-29-2011, 09:06 AM
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Originally Posted by Paul Bell
You guys might discover the cheep new coils that end up on ebay for 20 bucks were rejected by GM. These rejects then get dumped to the surplus market and eventually make their way to ebay.

Go buy a 50 cent light bulb at Pep Boys. Go home. Submit the online survey. Print out the 10% coupon. Go back to Pep Boys and buy new boxed coils-with a warranty. Use your 10% coupon.
i purchases low mileage used coils with brakets and wiring harness. If one of them of them it bad then ill replace as necessary...
Old 12-29-2011, 09:39 AM
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Originally Posted by wrd1972

6. Inspect the oval rubber seal found on the 4 wire opti connector that plugs into the top of the opti. This seal must be uniform looking and greased with dielectric grease to ensure water and moisture does not enter the opti. This thing should be replaced every year since it can be done in less than 10 minutes.


Being an opti noob, can I get the rubber seal at an auto parts store? or is it just a basic o-ring?
Old 12-31-2011, 01:50 PM
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Originally Posted by BackInBlack02
Is the IG switch goning out common? I'm at 158K and the switch is starting to go out, it takes a few times trying before it cranks.



I'm aobout to install a mallory IG box, same question, does adding an IG box kill the opti?



My opti has gone bad once only, swapped to a vented one, Delco, and no issues..... yet.




I tried the LT1 MSD coil, didn't last long, went back to stock and its still running. Also had the opti go out before the coil, not sure if the MSD coil caused it.
No, a Mallory 685 will not kill your opti.
Old 01-01-2012, 08:19 PM
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Originally Posted by TABR
Being an opti noob, can I get the rubber seal at an auto parts store? or is it just a basic o-ring?
Yes but again it will be on a "generic" already assembled connector in the electrical section.
Old 01-06-2012, 10:58 AM
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[QUOTE=wrd1972;15778069]Wow all of the opti hating is cracking me up.
The opti is an excellent distributor and does everything it should for most of us and can last a long time PROVIDED you know and address its quirks properly.
As already mentioned, genuine GM opti is the only way to go. ]



Ya, Great advise on preventing premature failure!! I have personally done that to 3 GM optis and 1 Chandler opti. The 3 GM opti's lasted 10K miles collectively!! I also went as far as converting to Elect. Water Pump to move it away from the opti a little; Not that it ever leaked!!The chandler is going on 20K now! Why spend $350 on GM unit thats just as likly to fail as any other? A GM mechanic buddy (26 years as GM mechanic) said the opti's are crap! They see them going bad at 40 to 50K on average! GM!!!
Old 01-06-2012, 11:27 AM
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^ I agree...I've owned my 94 Formula since 97 (149K now)....the original opti took a **** LONG ago around 65K (granted, it was a un-vented 94 opti) The second GM unit lasted about the same, another 60K or so. I'm using a MSD one now but can't really say anything good or bad about it since I have only started the new motor...not driven it yet. Just because a few people have "freak" optis LOL that last 200K does not mean the vast majority of LT1 owners face the dreaded dead opti if you own one long enough. It wouldn't annoy me as much it does if I didn't have a LS car to spoil me that never has any ignition issues.
Old 01-06-2012, 09:12 PM
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I would mention my experience but I dont want to jinx myself.

All kidding aside, Ive had few issues. Took my GM one off at 100K. Worked fine but bearing wasnt as smooth as a new one,

Put a new GM one in with cam, lasted 20K miles spinning car to 7k and screws fell out of rotor, I may have cracked the rotor on installation, whos knows. Put parts house one in. Cardone I think.

Around 140K Seal on back of opti failed, Filled opti with oil, started cuttin out occasionally. Three months later it died, when I took it apart, it was completely full, no **** COMPLETELY full of oil. Like submerged. Cleaned it out and it still worked but I got another one anyways and installed it.

Keep the oil diver opti as a spare.

I actually havent had an optical sensor that just died and thats what everyone cries about. Overall Im happy with the opti.

Im hard on stuff and Ive come to realize, I have to buy expensive gas and it not gonna last long, and ***** gonna break.


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