Purchased it yesterday and am waiting for delivery. Still hunting for LS1 coilpacks.

This system does not eliminate the opti all together as it still utilizes the hi/lo resolution optical sensors. The high voltage stuff is not used and I believe the rotor can be eliminated.

I have no complaints about the opti - mine has 108k on it, has survived a waterpump failure (caught it early) and its still going! I've had recent issues with coil and ICM failures and when I took a step back and thought about replacing opti/ICM/coil with new quality units would cost a good amount of coin. The LTCC and LS1 coilpacks do cost more - no doubt about it and still require a working opti, but I get the benefit of a more reliable ignition and a stronger spark at that. So for a little more cash it was worth it to me.

Now, I have some question marks...
Since I still need a working opti I'm considering replacing it. Mine still works but at 108k it has exceeded my expectations - I may leave it in there until I do a cam install (hopefully this winter). My car is a 94 and it uses the non vented opti. To the best of my knowledge the advantage of a vented opti is that manifold vacuum is able to evacuate the damaging ozone created by the high voltage running through it and pull in filtered fresh air. Since I will be eliminating the high voltage aspect is it reasonable to believe that I will not have the ozone issue and hence the need for a vented opti? Are there any other advantages to a vented opti? Better bearings/bushings? Etc? So that is one arguement to not convert to the newer style.

I plan on upgrading to an aftermarket cam at some point in the future. Does the aftermarket support cams with provisions for non vented optis or is the selection limited/non existant? This is where my concern lies. Am I shooting myself in the foot on cam selection by not converting to a vented? I was considering the LT4 Hotcam but I think it can only use a vented opti. As an alternative I believe Loyd Elliot offers a cam similar to a hotcam but I am unsure if it will work with my non vented opti.

 

If you stay with the original style OPTI (non-vented) all you have to do is shorten the drive pin on the cam, tap it in or cut it to the correct lenght (use stock cam as guide).

If using the LTCC setup I would stay with the original style and remove the rotor. Others may know of some other reason to change but I do not know of any. If not going to LTCC I would and did convert.

 

Thanks for the reply.

Excuse my ignorance but perhaps I am confused.
On the non vented opti motors how is the opti driven? I've never had an Opti off the motor. I could be mistaken but I thought the non vented Opti had a splined shaft that fit into a splined hole in the end of the camshaft? Is this incorrect? I know the waterpump is driven by a splined shaft and perhaps that is what I am thinking of.

From what you are saying above it sounds like both the vented and non vented optis are driven by a pin - and the difference is that a vented opti uses a longer pin and hence a camshaft designed for a vented opti can be used in a non vented application by shortening that pin?

Long story short - I can use an LT4 Hotcam with a non vented opti? If so that is good news as I can continue to use my existing opti if I choose and I don't need to update my timing cover to a 95+.

 

Yes, the hotcam will work with the non-vented opti. I ran that setup a few years back for about 5k miles then decided to go bigger and go to vented opti.

 

Got the LTCC installed yesterday.
This thing fired up at the first flick of the key with no issues. The product seems to be great quality and the wiring is well packaged. Install is almost entirely plug and play. The only splicing I had to do was to tap into the 12v+ wire off the original coil harness and the EST wire on the original ICM harness (neither the original coil or ICM are used). I was really happy to have it fire up problem free.

Haven't driven it yet as I still need to button up a few things as well as permanently mount the LTCC 'brain' box. The instructions indicate to mount it away from heat sources and not directly to the engine (vibrations may damage it). The two options I saw were down by the battery or up on the fan shroud next to the air intake. I opted for the fan shroud location for ease of install and future accessability. I don't think it gets too hot there and there should be some air movement while in motion.

On startup the engine settled to a very smooth idle - possibly smoother than the factory setup but that may be wishful thinking. I gave it a few revs ~3k rpm and it seemed to rev up much faster BUT I do not have the accessory belt installed so the lack of parasitic drag off the accessories is the likely reason for that. Hopefully will have driving impressions today.

 

Hope everything works perfect for you, but remember you are replacing a part w/108k miles with one that has 0 miles, so you really cannot compare the two.

Was curious if you would need to tune your ECM, as it seems if you look at the engine to long, you need to get a tune. Because 93's ECMs do not take any changes.

 

Well, good point but in the LTCCs defense the Optispark is in fact still the original with all 108k miles - still working and that is what is driving the signals fed to the LTCC. The LT1 coil and ICM had been replaced multiple times - I had a new MSD coil and new aftermarket ICM in late 2009. The MSD coil lasted a few months at which time I replaced both the coil and ICM with a used OEM and have been running that since.

The LS1 coils should be providing a stronger spark over any stock LT1 single coil setup and at the same time I eliminated the high voltage through the Opti.

I doubt the ECM knows the difference. Mine is a 94 and although still OBDI the pcm is not the same as the 93.

 

Did you have a look to see if your instrument panel tach is still working and whether the ASR light is on?

We have a '94 and had both happen when we installed the LTCC. Seems on the '94 the tach and ASR feed come from the ignition module via the tach filter.

Not all is lost though, as the ECM is the exact same part number for the 94 and 95. All that is needed is to take the tach signal coming off PIN A13 of the ECM and run it over to the wire that was attached to the tach filter. You will need a terminal in the terminal block though (ask Bob Bailey about that)

 

THANK YOU!
I was about to ask about this. Yes, in fact my Service ASR light is now illuminated and I'm not even sure if I looked at the tach on the instrument panel.

Can you elaborate a bit? I follow the part about Pin A13 off the ecm carrying the signal but I'm not sure where I am running that signal to? The tach filter, as far as I know, is that little black box that just dangles by where the original coil and ICM were mounted. It has 2 wires going into it, will I need to feed the signal off Pin A13 into one of those wires? Is there a closer spot near the ecm or do I need to actually run the wire all the way to the tach filter?

Not sure what terminal block you are speaking of?

EDIT: I thought about this and I assume that the terminal block you are refering to is in fact connector A on the ecm and that although Pin A13 carries the tach signal there is no pin or wire in the A13 spot. So, I would need to add a pin and run a wire from A13 to the tach filter to correct my problems. That only leaves me wondering if it matters which wire at the tach filter I splice into since there are 2. Is my thinking correct?

Last night after I had everything under the hood all buttoned up I decided I would go for a ride and take the girlfriend to get some icecream - I really just wanted to drive the Vette and the icecream was an excuse. I had the motor running, flipped the headlights up and had one eye out. What a kick in the pants! Ended up taking the other car and I'm glad I did - went through a sobriety checkpoint run by state police, I'm sure a 1 eyed corvette wouldve gotten me a citation to get it fixed.

 

I had a shop do the work on the car to run the wire as I work 350 miles from home and its my wife's car, and it is a year round daily driver. In other words, it needs to be ready to go all the time.

Yes, your thinking is correct. That is what I meant. We ran the wire all the way from the ECM over to the ignition module area. I am not sure which wire coming off the tach filter it is connected to (the shop did that connection).

In the link below, there are some pictures of our install. Maybe something will be helpful there. The white wire is the one that comes of fthe ECM and goes over to the ignition module/tach filter area.

http://s49.photobucket.com/albums/f2...TCC%20Install/

I will have a look to see which wire was connected to at the tach filter.

 

The wire from A13 on the ECM is connected to a white wire at the tach filter.

 

Thank you for your help.
Bob Bailey is sending me the pin for the pcm connector. In the mean time I ran a wire from the white wires up where the tach filter used to be to pin A13. As a temporary solution I stuck the bare copper end of the wire through the A13 hole and reinserted the connector to the pcm. The connection is adequate and I have a tach signal and the ASR light is no longer illuminated. I'll be doing it right once I get the pin.

I've driven about 100 miles with LTCC setup and I gotta say it is great! Not a single misfire from the motor. It revs smooth, feels a bit stronger in the upper revs and my off idle torque response seems improved. I'm really happy with it so far.

 

Glad to hear it worked out and is working well.

On our setup I have been chasing a mis-fire at low RPMs at light throttle. It ha been driving me CRAZY. I think I finally tracked it down to four bad spark plug wires on the driver's side. A new opti terminal/boot kit is on order so I can make up some new wires.

 

Good luck getting yours straightened out. The reason I went to the LTCC was to avoid misfires and seemingly endless coil/ICM problems - I sure would have been frustrated if those probs persisted. Getting the high voltage out of the opti is another nice benefit.

What kind of spark plug wires are you using?
Remember, Bob Bailey does not reccomend using low resistance wires (like MSD Superconductors) because they cause known issues with the LTCC - I don't believe he gets into what may happen. I'm sure you're aware though so this is probably a moot point.

 

Using Taylor wires right now. Still searching for a replacement set, as I need a set of wires with right angle boots at the spark plug end.

Good reminder to not use low resistance wires.

We went with the LTCC to get the high voltage out of the opti as well. After 7-8 opti's I said ENOUGH.

Sure looking forward to getting this miss behind us.

On the bright side it has resulted in some needed maintenance/parts replacement to get done...........like new injectors, spark plugs, etc.

 

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