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

How hard is it to replace the opti?

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Old Jan 12, 2007 | 04:04 PM
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Default How hard is it to replace the opti?

We replaced the waterpump awhile back, and I think we had to remove the opti, too. I don't remember it being too difficult.

I'm sure it's the opti that crapped out. A couple of weeks ago, it just died in the middle of the road. It just died out of nowhere I think twice more after that. Yesterday afternoon, it started running weirdly so I pulled into a parking lot. Then, it died. Everything would happen, except run. I could hear the fuel pump, it turned over and everything. Last night after several hours, we went back and it "ran" for like 30 seconds then died.
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Old Jan 12, 2007 | 04:08 PM
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It's easy
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Old Jan 12, 2007 | 04:08 PM
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Originally Posted by ZFan88
It's easy
You think it's the opti? The car has 188K miles on it. I have no idea if it's the original opti or not.
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Old Jan 12, 2007 | 04:16 PM
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hard to say, you can isolate whether or not it's the opti though, pull the coil wire from the opti, ground to block/head (use some insulate pliars keep from getting shocked if you have old crapped out wires), crank it over check for spark, if it sparks that at least temporarily rules out the coil (which could still be bad, theres a multitest you can do to check the ohms). Now hook back the coil wire and crank it over with say like #1 plug & wire (ground to block/head) if you have a spark there too, then usually the opti is ok. That does not rule out individual bad wires/plugs, but is a quick general test for where you are at least getting spark.

My buddy had no FIRE through the opti, but fired from the coil, yet wouldn't start, turned out the coil was bad, it sparked but was weak, the ohms were out of wack. There is a write-up/how-to of what the ohms should be for a stock coil somewhere, will post if I find it. If your using an MSD BlasterCoil the ohms will be different for determining whether or not it's bad, forgot what was considered good for the MSD.

That is a lot of miles for an opti though.
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Old Jan 12, 2007 | 04:25 PM
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Originally Posted by BRETTINATOR
hard to say, you can isolate whether or not it's the opti though, pull the coil wire from the opti, ground to block/head (use some insulate pliars keep from getting shocked if you have old crapped out wires), crank it over check for spark, if it sparks that at least temporarily rules out the coil (which could still be bad, theres a multitest you can do to check the ohms). Now hook back the coil wire and crank it over with say like #1 plug & wire (ground to block/head) if you have a spark there too, then usually the opti is ok. That does not rule out individual bad wires/plugs, but is a quick general test for where you are at least getting spark.

My buddy had no FIRE through the opti, but fired from the coil, yet wouldn't start, turned out the coil was bad, it sparked but was weak, the ohms were out of wack. There is a write-up/how-to of what the ohms should be for a stock coil somewhere, will post if I find it. If your using an MSD BlasterCoil the ohms will be different for determining whether or not it's bad, forgot what was considered good for the MSD.

That is a lot of miles for an opti though.
So, pull coil wire from opti and ground to block/head. Crank it over, if there's a spark, the coil pack seemingly is good.

The plugs and wires are overdue for a change, though. I have those sitting in my room. Should we replace those first? I know they're a pain in the butt, too.

Repeat with plug and wire #1. If it sparks, then the opti is seemingly good.
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Old Jan 12, 2007 | 04:29 PM
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Originally Posted by Shackleford
So, pull coil wire from opti and ground to block/head. Crank it over, if there's a spark, the coil pack seemingly is good.

The plugs and wires are overdue for a change, though. I have those sitting in my room. Should we replace those first? I know they're a pain in the butt, too.

Repeat with plug and wire #1. If it sparks, then the opti is seemingly good.
Yeah if it were me I'd change the plugs/wires regardless just because it's time, and correct if the plus w/boot/wire spark then opti is at least getting spark. That doesn't mean it doesn't have issues, but it's a quick diagnostic is all. The Mitsubishi eye sensor could be bad or dirty, the bearing could be shot on the sensor causing erratic readings of the little timing wheel, yada yada yada.

You could still quickly check for spark though prior changing any wires, just to see, won't hurt anything.
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Old Jan 12, 2007 | 04:31 PM
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Originally Posted by BRETTINATOR
Yeah if it were me I'd change the plugs/wires regardless just because it's time, and correct if the plus w/boot/wire spark then opti is at least getting spark. That doesn't mean it doesn't have issues, but it's a quick diagnostic is all. The Mitsubishi eye sensor could be bad or dirty, the bearing could be shot on the sensor causing erratic readings of the little timing wheel, yada yada yada.

You could still quickly check for spark though prior changing any wires, just to see, won't hurt anything.
I kind of hope it's bad because I bought a used one last night. lol. It wasn't too much, though. It has almost half the miles as mine.

I have Taylor 8mm wires and NGK plugs. Will I need anything else? Any tips for the plugs and wires change?
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Old Jan 12, 2007 | 07:01 PM
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Originally Posted by Shackleford

I have Taylor 8mm wires and NGK plugs. Will I need anything else? Any tips for the plugs and wires change?

TIP: Have someone with super skinny arms do the passenger side wires . I took my alternator off to help with routing the wires through the accesory bracket.
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Old Jan 12, 2007 | 07:54 PM
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To change the OPTI, if that is worst case, it will take you a bit. Takes me a little over an Hour, but I have a few less things in the way. Might not be that though, check everything close to it. Could be ICM..
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Old Jan 12, 2007 | 08:01 PM
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Originally Posted by the_merv
To change the OPTI, if that is worst case, it will take you a bit. Takes me a little over an Hour, but I have a few less things in the way. Might not be that though, check everything close to it. Could be ICM..
What all should I check and how do I check it?
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Old Jan 12, 2007 | 08:04 PM
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If you have spark from the Coil, that's good, but like mentioned before, it might not be enough. If everything is as old as it is(I doubt it, but you never know), it could be the OPTI going. My old Coil was 110k old, it was causing a misfire up past the 5500 RPM mark. I replaced it and have no problems.
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Old Jan 12, 2007 | 08:17 PM
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Originally Posted by the_merv
If you have spark from the Coil, that's good, but like mentioned before, it might not be enough. If everything is as old as it is(I doubt it, but you never know), it could be the OPTI going. My old Coil was 110k old, it was causing a misfire up past the 5500 RPM mark. I replaced it and have no problems.
How much is a new coil?
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Old Jan 12, 2007 | 08:17 PM
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I think it's like 50 bucks for the blaster coil from MSD. Check out a sponsor..
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Old Jan 12, 2007 | 08:20 PM
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Originally Posted by ZFan88
I think it's like 50 bucks for the blaster coil from MSD. Check out a sponsor..
Eh. I'd probably just buy in town here.
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Old Jan 12, 2007 | 08:23 PM
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Go to Autozone, got the MSD Blaster for $39.50.
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Old Jan 12, 2007 | 08:25 PM
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just buy an ls1 car
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Old Jan 12, 2007 | 08:32 PM
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Or just install a LSX series motor..I am looking into that eventually.
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Old Jan 12, 2007 | 08:43 PM
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Originally Posted by S99TA
just buy an ls1 car
If I had the money I would.
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