motodog

looking at an lt4 corvette. for you guys that have one what do I do about the opti? that is the one thing that deters me. also can it be converted? mods ect. how do they run against c5's ect. bring me up to speed please. thanks..

MatthewMiller

Don't let the opti scare you away. Those don't fail nearly as often as people think - a lot of problems that are blamed on the opti aren't actually caused by it. If you ever do have to replace it, the labor isn't as terrible as many people make it out to be, and there are at least three good options for replacements. The only potential "gotcha" with a 96 C4 is that it's the first year of OBD2, which may mean more stringent emissions inspection requirements where you live. It also means that in order to tune it or turn of self-diagnostics (if you make significant mods) you need more expensive software than for earlier cars (Jet DST). Not a big deal, especially if you plan to keep it stock.

cv67

they run about the same as a stock C5

MatthewMiller

Oh yeah, forgot to add that. Yep, the LT4 was pretty much identical in performance to an LS1. Both are very sweet engines.

SJW

LT4 has the much improved, second-generation Opti, with active venting, revised bearing, etc. These tend to be much more durable than the first-gen units. As others have already advised, don't fear it.

And, yes, the LT4 can run with the big dogs. If you haven't driven one yet, it'll surprise you when you do.

Live well,

SJW

BlowerWorks

The LT4 is a VERY sweet ride - You shift at 6400 RPM - OMG soooooo nice !!!!!!!!!

dizwiz24

The optispark had gotten a bad rap due to geniuses thinking a cheap chinese replacement unit is the same as a NOS OEM optispark.

they replace their optispark with a piece of chinese garbage for whatever reason and then falsely believe all optisparks are garbage when it doesnt work.

some people were sold cars with faulty chinese optisparks by PO’s who couldnt get the car to run right so they sold it.

the conversions dont even eliminate the optispark entirely . They still require it.

cv67

Gen 1 guys do the same thing with $69 HEIs and complain about breaking down Ill never understand it.

Jitsu

I've owned an LT1 and currently an LT4 and never had opti trouble with either. The thing to look for specific to 96 models is the AC tends to have an issue switching from defrost to forward vent due to a rubber material used on the vacuum control that weakens and thus affects pressure. So basically your AC only blows out defrost. The box us underneath the dash to pull out and fix.

https://www.corvetteforum.com/forums/c4-tech-performance/1514042-96-hvac-vent-control-problem.html

Bill781

I really appreciate this post, thanks. Noticed the A/C vent buttons on my '96 GS didn't seem to respond to inputs--also air didn't feel all that cold. Took her to a dealer, they checked the system, found no leaks, recharged. Cold air comes in now, but it seems to simply respond to the "auto" setting as supposed to specific vent selections.

This makes sense now.

MatthewMiller

To add detail here, I think that only applies to 96s with the automatic HVAC controls, right? If you get a really bare-bones-optioned 96 with the manual HVAC controls, like I have, I don't think this is a problem. But someone please correct me if I'm wrong about that!

Jitsu

I believe you are correct. I forgot that there was a different HVAC control option but I admit I don't see it that often. I wonder how many manual vs automatic HVACs were sold?

Mine has the automatic HVAC and the issue is present but it has never really been an issue for me since I typically have the top down.

Its a minor issue that should not dissuade a buyer from purchasing an otherwise good condition 96.

puterami

Do the lights for the buttons light up when you select them, or not?
My 96 (C68) all of the buttons would work almost all of the time when I first start it. After driving a while several buttons would not work (select). Yet, the air was diverted where it should be for the buttons that did work.
If this is the case what I just did is take out the controller, take it apart and clean the buttons and electronic actuators with "Electronic Parts Cleaner" spray and reset the board.
All of the buttons now work, but I have not had time to drive it so my testing is only preliminary.
If this doesn't work, I'll send it to Bryan Thompson (batee.com) to have rebuilt.
BTW, I liked BAT's video on taking it apart.

powerplaytwo

I bought mine in July and love the car. I am still in the process of doing the baseline maintenance. It is a great car to cruise with the top down. My AC has the problem as the air takes about 5 minutes to come out the right vents, but I am going to fix that next. I have changed all the fluids and cleaned up the interior a bit and she is looking good.