LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

97 lt1 missfire on #7 i need help!

Old 06-17-2018, 01:51 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by 97sswcubes View Post
Exactly what i needed thanks.
Called sumit and they shipping me another opti and see how it goes.
Because of the high failure rate of the after market units, and the amount required to get to them I would honestly request a refund and buy an AC Delco. Time = money in my book.
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Old 06-17-2018, 01:51 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by shoebox View Post
If it is an aftermarket hub (not sure it was ever mentioned), you'll have to pull it. The stock hub you don't.
Rob, FWIW I have the ATI Hub/Damper and the opti can be removed without pulling the hub

IDK about other non stock hubs but the ATI can be left on to get the Opti off.

EDIT: ATI hub pic
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Last edited by Chimera96; 06-17-2018 at 11:21 PM.
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Old 06-17-2018, 04:19 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96 View Post
Rob, FWIW I have the ATI Hub/Damper and the opti can be removed without pulling the hub

IDK about other non stock hubs but the ATI can be left on to get the Opti off.
I guess they are not all the same are far as interference goes. Good to know.
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Old 06-17-2018, 07:18 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by DrewHMS97SS View Post
Because of the high failure rate of the after market units, and the amount required to get to them I would honestly request a refund and buy an AC Delco. Time = money in my book.
You are most likely right about the aftermarket optis. Had a ac delco unit in the car brand new when it flooded. Was ruined but managed to get my money back but ac delcos were no longer available and no dates on future availability.
So i decided to give a sumit R unit a try. If the one i get goes bad before warranty expires I'll see about getting my money back and I'll go torque head. Don't want to live in fear of the opti going out or a defective unit. But at the moment not ready to shed $1600 for the torque head yet..
Its alot of money for ignition really wish they'd make it more affordable and maybe they'd sell a whole lot more.

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Old 06-22-2018, 10:44 PM
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Re: 97 lt1 missfire on #7 i need help!

Lack of availability and finding local tuners is why I switched to the EFI Connections 24x kit years ago, it just gets rid of all the opti related issues.
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Old 06-23-2018, 03:29 PM
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Re: 97 lt1 missfire on #7 i need help!

Ok so here i am lookin at this beast about to put it back together and i noticed something. The dowel pin on the cam is not as long as the stock camshaft.
I took notice because i understand the pin inserts in the square slot on the optispark.. But if it doesn't reach the inside the optispark won't spin. Here's a few pictures and if anyone can give me their opinion id appreciate it.
Center picture is stock camshaft
​​​​​​

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Old 06-23-2018, 04:06 PM
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Re: 97 lt1 missfire on #7 i need help!

It should really be ~ .620", but I don't see how that is going to cause a problem on #7 only. You should be able to look at the back of your opti and see depth witness marks from where the dowel pin has been riding.
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Old 06-23-2018, 04:17 PM
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Re: 97 lt1 missfire on #7 i need help!

Decided to move ahead and got the opti on. Marked the slot on the top of the rim where the slot for the pin is located and got it on. Rotor locked up and no movement. Had to do
it with the cap off.
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Old 06-24-2018, 05:07 PM
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Re: 97 lt1 missfire on #7 i need help!

So i got this thing put together over the weekend and fired right up! Reved clean and fast no hesitation.. But yet #7 still not firing like it supposed to. When reved their is noticibly more spark but more like a bolt of lightning without cut off than a spark. Its ... .......... .... Then nothing when let off the gas. Could it be a ground? Somewhere? Or is it the ecm that got flooded? Should i open it up and clean it with some wire brush and electrical spray? Don't know what else todo. Ecm is the last straw then im callin pick your part to come get it.
Not really but id love to get it 100% sometime soon!
One more thing, the guy that initially got this car runnin had to grind down a plastic edge on the opti connect to car harness. Or the other way around. Any chance there could be a bad connection at that harness?
Aslo gkt the security light on, wonder if that could cause missfire. Grinding occurred where those two meet

Last edited by 97sswcubes; 06-24-2018 at 05:11 PM.
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Old 06-24-2018, 06:04 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by shoebox View Post
It should really be ~ .620", but I don't see how that is going to cause a problem on #7 only. You should be able to look at the back of your opti and see depth witness marks from where the dowel pin has been riding.
Got the new opti on and new ac delco 02 sensors on. Fired up clean and reved really clean but still got the smell of raw fuel after a min. So i checked the plug wire #7 and it fired randomly. Put it back on and after a few times of checking things the engine didn't rev as clean as it did the first few times i started it with the new opti and o2s. It went back to sounding the way it did before the opti swap. Even the tick sound in the exhaust was noticeable. Last thing to try is swaping the ecm for one that didn't get flooded. Just afraid I'll throw my money down the exhaust pipe again and the problem still will be there.

​​​​​Thanks for the advice
​​​​​​Any other ideas?
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Old 06-26-2018, 11:49 PM
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Re: 97 lt1 missfire on #7 i need help!

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Old 06-27-2018, 10:32 AM
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Re: 97 lt1 missfire on #7 i need help!

From everything said, it's looked like the PCM is most likely this issue due to the water issue. It still could be the aftermarket opti.

I think you said PCM for less did your tune, you might be able to get them to copy the turn from one PCM to the other at a discount based on your circumstances. It never hurts to ask.
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Old 07-02-2018, 06:22 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by DrewHMS97SS View Post
From everything said, it's looked like the PCM is most likely this issue due to the water issue. It still could be the aftermarket opti.

I think you said PCM for less did your tune, you might be able to get them to copy the turn from one PCM to the other at a discount based on your circumstances. It never hurts to ask.
Well i got bad news. I actually did get a pcm from pcm for less at a great price with the tune i had on the flooded pcm.
I got it in today and installed it & cracked it up. Well, its still there the miss. Damn thing won't go away and i dont know what else to do but set fire to the damn thing. Very upset and wishing id bought an ls camaro instead of this nightmare LT OPTISPARK CRAP. Where else can i look, what other wires is there to check? Jesus christ i owned a 5.0 Mustang and never had these kind of troubles. It just shouldn't be this difficult to get an ignition running correctly but this opticrap has all kinds of issues its lile finding a needle in a haystack.
If anyone out there has anymore suggedtions id appreciate it so much.

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Old 07-03-2018, 09:59 AM
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Re: 97 lt1 missfire on #7 i need help!

is the #7 FI wiring solid...(read have you checked for any break in that wire within the harness)?
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Old 07-05-2018, 12:37 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96 View Post
is the #7 FI wiring solid...(read have you checked for any break in that wire within the harness)?
Tell you the truth i dont know how to check for what you just mentioned. I think i will have to find a shop that still actually knows how to work on these dinosaurs. Cuz i cant seem to find the problem.
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