Readers digest version:
"Bought one of the first LTCC kits with the individual long wires to each coil in 2003. Fired up first time. Then when motor went out in 2004(oil pump drive gear sheared off all teeth), I sold that LTCC kit to a fellow Fbud, vowing to buy another LTCC when the engine was rebuilt. Bought the next LTCC kit in 2008 with the integrated wiring. It utilizes the stock LS1 wiring harness. It didn't work, car ran like crap, backfired, gas fouled plugs. Gave up after month of trying and went back to stock OPTISPARK."


Fast forward to last night, since I'd torn a spark plug wire off the stock Opti, I decided to re-install the LTCC. Hooked it all up and tried to start. Same crap as 2008. FML.... Checked all connectors and all seemed to be well. Cussed and went out to dinner with the wife. As I'm driving to the restaurant, a thought popped in my head.... "How do I know if the LS1 coil harness is oriented 1,3,5 and 7 on the drivers side? If I have it *upside* down from stock it would be backwards. But, how can I tell if it's rightside up? It's not marked with *this side up*, etc." So I went out this morning and flipped the coil pack assembly over and plugged the plug wires into each coil. I tried to start it but it was still running like crap, flooding. Dammit!! I thought, how can I decide if each side is correct?", then the next thought came to me. "Pull out the plug from cylinder one, put the plug on it's plug wire on the fender so you can see when it sparks, then stick a finger over the plug hole in the cylinder and crank it. When the cylinder pushes the air out of the cylinder with the most force, it should be a compression stroke. At that time, the spark on the spark plug should occur. If it's NOT timed with that, it must be oriented backwards.". I pulled the injector fuse out so no fuel would be there in the other cylinders, turned on the ignition key, then attached my remote starter , pulled the #1 spark plug, installed it in the wire, grounded it so it would spark when it got the charge, put my left finger over the plug hole and pressed the remote starter. Aha! It IS on there backwards. I reversed the wires, the put the plug back in, it's plug wire on and moved over to cylinder #2(first cylinder on the passenger side of the motor). Same thing, it was backwards. After putting everything in place and securing it all, I got in the car, said a small prayer and turned the key to 'start'.VROOM! She started right up and ran smoother than ever.


In the preliminary 'readers digest' version, I didn't go into the sordid details of what all I did when trying to figure out why it ran like crap initially in 2008. Apparently the whole time, the coils were, by accident backwards, when I tried the LS1 factory harness. So no matter what I did, it still ran like crap because the issue was ALWAYS the coils were firing out of order.

• Sent LTCC back to Bob Bailey, telling him it wasn't firing correctly. He put it on his test mule and it ran fine. Sent it back to me, no charge.
• replaced injectors (thought one or more was clogged)
• replaced coils (thought one or more was bad)
• Went thru 30 different PCM Tune settings trying to get it to stop flooding. Of course nothing helped
• Bought a new engine compartment wiring harness(thought I had a short)
• Bought a new GM Optispark(thinking the new Jegs opti was faulty)
• Took timing cover off and verfied cam timing was correct, introducing a nice oil leak at the oil pan/timing cover in the process.
• Sent LTCC to a bud of mine in Austin that has a working LTCC. Asked him to put my box in place of his to see if it ran. It ran perfectly.
• Sent LTCC and LTCC harness to Bob Bailey, thinking it must be the harness. It worked fine. Bob Sent it back, no charge.

When I decided to just forego the LTCC and use the regular Optispark, it ran fine.

I had unintentionally installed the coil harness unside down (since I hadn't thought about that aspect) by installing it for conveniences sake, trying to put it where it was least visible to the visitors eyes. I feel like such a fool for not recognizing this issue back in 2008.

Just sharing here so that if someone else decides to use the stock LS1 harness, they establish which way the harness or plug wires must go before they try to fire it up.

 

Thanks for sharing. I'm about to install the LTCC and usually if there is a way to mess something up, I'll find it.

 

Nice! The first box worked flawlessly for me because it had the individual wires from the box to each coil. But the installed harness looked like a large octopus had been laid on top of the engine. I've installed my coils in various ways thru the years...

This was my first setup when my motor was only heads, headers and cam(plus nitrous)
LTCC Installation = Fbody

This was my second setup...








And here is the current setup...



Make sure the white wire from the ICM (not the coil) goes to the white wire from the LTCC. The LTCC needs the A/C signal from the ICM wire to know when to spark. My original LTCC pamphlet instructions said to use the white wire "from the coil".

 

Love it now? I am this close to buying one.

 

Yes! Plus, it has a built in facility for use as either a timing retard (for forced induction/n2o) or a rev limiter, ala "two step". All you have to do is set the DIP switch inside the box for either retard or rev limit, then when you want to activate it, simply apply a 12v signal to the already provided yellow wire and , viola! it's activated. So, by merely attaching a momentary switch and the 12v, you're good to go

I have mine set to use the 5,000rpm Rev limit for staging at the drag strip. By hooking it to my line lock, I lock the brakes, press the button, release the brake pedal. Then floor the gas pedal and when the lights start to come down. When I release the line lock, the rev limiter is disabled and off we go.

 

I got lucky with mine,it was the newest version..Best money I have ever spent..I will post up some pics of mine installed later today..

 

I know this is a necro-thread but finding out that the LS1 harnesses can go on backwards, saved me an asston of troubleshooting.
So I'm giving it a bump so that someone else can find it in the futurej


(finally installed an LTCC since the new GM OPTIs come from Mexico and I can't keep a mexican rotor in one piece

Its sad since I never broke the old US made OPTIs.


Long story short car was hard to start and backfiring , my drivers side harness was upside down......
Mike

 

Glad to see it's still helping folks. Oddly enough, I had a revisit of this ghost when I swapped in the turbo 5.3. I'd sold my still running turbo Lt1 to a gent in Austin that planned to put it in a 96ss Impala and with it went my harnesses etc.

I bought the 2002 Silverado 5.3 with 190K on it, had it gone thru completely with new forged everything. After receiving it, I bought the harnesses and coils from someone on EBay and everything was separate. You can guess what happened when I first tried to fire it up. It only took me a few hours of very impressive cussing to remember about the harness orientation. Flipped it and life was good.