I have seen this as the most common problem on the LT1's. Most people write in here looking for answers and everyone has a list of things to try. What did you finally narrow it down to, if you ever did? I never have. You can even list all the things you tried and how much your into this thing. I have replaced the Opti, plugs, wires, icm, coil, coil wire, fuel filter & fuel pump. Total so far & $700+

 

Throwing parts at it was your first mistake. There are tests to verify proper working order for pretty much everything you have listed there. It could be as simple as your FMU and 2400 watt amp pulling too much power at WOT. I don't think the problem has nor ever will be narrowed down; there are too many variables.

 

How do you check the FMU to make sure it is running right? What happens if i run the car with the FMU disconnected?

 

Coil wire was my problem, Make sure its clicks on nice and tight, mine wasn't on ALL the way and caused a problem.

 

Kaboooom!!!

I guess to check it, see if it is holding vacuum, you can get a vacuum pump pretty cheap at most parts stores.

 

I'd like to know this answer as well. I'm trying to track down the problem.

 

I did try unhooking the inline pump and my fuel pressure dropped a few psi. Now the miss is twice as noticable. I guess fuel is a good possibility. I like the idea of the fmu being at fault because it runs great if i take the blower belt off and just run it normal.

 

What I found to correct the problem (assuming you have LT1 Edit) is to reduce your timing in the 90 and 100 KPA cells (PE) to about 25* or less. And to change the Burst Knock enable temp to 110*C to essentially disable it. My engine was seeing (and probably correctly identifying) knock and pulling timing out. Runs smooth to redline now without any hickup.

 

added in a ltcc and problem solved, LOL

 

I still have a high rpm miss and have run out of ideas myself. Pretty much replaced everything that I can. Only thing left for me to do is the LS1 swap mod it looks like cause I'm giving up.

 

I heard folks have had good luck with the full MSD opti replacement

 

i tightened my #4 spark plug! fixed

 

Now your car is as good as new...

 

Done that too :-/