Well the good part is that I finally got a REAL tune on the car and this is how it did...



Which I am not unhappy with EXCEPT for the misfire around 5800 rpm. It had the same miss last time it was on the dyno so I installed an MSD coil, MSD wires in stock location with heat sleeves over the boot as well as silicone looms and some zip ties, MSD 6AL2, and did the ICM cooling mod as well as new spark plugs gapped to .045 (motor is 11:1)...same misfire. I replaced the cap and rotor about 3000 miles ago I put the MSD cap and rotor on the original factory opti and I did put loctite on the rotor screws. We did several pulls, misfire always comes in at the same rpm and it consistently makes the same power the only things that are not brand new are the opti and ICM. Has anyone had a similar issue with a high rpm misfire and it did in fact turn out to be a bad opti?

 

Thats the same thing mine was doing with 205k on the stock opti. I swapped it out with a new one now runs perfect

 

take your icm off and get it checked. Im beting its the opti tho. nice numbers btw

 

Eh, not bad.

 

Pretty good for out the box heads and tiny cam. I'm betting opti too.

 

thanks, I think?

I told myself as soon as the 24x conversion came out that I would never buy a new opti and if mine **** the bed I will do the swap. It kinda sucks though as I just purchased that 6AL2 and a new coil

 

Mine does the same thing and my opti is fairly new so I havent figured this one out yet...

 

Lot of times dips around 5800 are due to valve springs, but I know nothing about your cam/valvetrain setup, so that's not what I'm saying... just saying.

 

Not hijacking this guys thread, but my setup:

Comp XE 230/236 .510/.520 112
Comp Magnum Roller tip SA 1.6 rr
Comp 3/8 rocker studs
Trickflow chromoly pushrods 7.2
Patriot gold dual spring kit good for .650

I rev to 6300 and this little dip happens a few times actually anywhere from 5k-6300 and it does it in 2nd gear and up.

And it randomly didnt do it when I had it dynoed so I didnt have that to go by...

 

Im battling the same thing 5800-6200 or so then its fine after the miss. It does it 2-4 times almost sounds like a rev limiter Then pulls fine to the shift point. Ive been through optis, plugs, plug wires, ign modules, coils, crank sensors and even another computer and tune. We recently played with plug gap on the dyno thinking of possible spark blowout but it proved not to be an issue. This thing is a pain in the ***.

 

what about valve springs? If I am not mistaken if it were valve float the power doesn't dip but it just falls off. I don't think there is any way in hell my valves could float with the springs that are on these heads. Too much spring for a hydraulic roller if you ask me 150 on seat 450 open

 

My car had a bad misfire above 6000rpm. It sounded like it was on the rev limiter, just breaking up and sputtering. At ANY rpm below that it was 100% fine. The car would cruise and idle just fine. Finally bit the bullet and got an MSD opti. Totally cured it. When we took my opti apart you couls see the tiny pieces of bearing material in the cap and the rotor could wobble a little bit. The center bearing was toast and it disentegrated. Probably got a little moisture in it and corroded over time.

 

Good numbers first off. and my car has the Same missfire! i havent played with spark plug gap but everything is brand new. first gear revs out fine. from 2nd and up itll break up around 6k. im running patriot extremems which i know arent the cause. its either opti or lifters themselves being bad. even tho there fairly new ls7's... if you figure it out please let us know!

 

I chased this dreaded miss for a long time too, and it turned out to be my PCM.

 

A friend of mine had an Opti he bought from All Ignition. He was having the same exact issue at 5800. He sent it back on warranty 3 times and it was never fixed. He installed an opti off a low mileage car and problem fixed. I dunno where you got if from but, we pulled his apart and the reluctor wheel was scrubbing the optical eye. We even replaced the parts ourselves with a donor opti that had a bad cap and same problem. We believe it was a casting flaw on the base of the opti.

 

a flaw in a base opti? Thats hard to beleave.

 

The only constant was the opti base. I dunno. It's just a guess.

 

i was being sarcastic. Like many people will say, the opti is a great idea just poorly executed.

 

well said. the opti itself is a great unit. to bad its achilles' heel is water

 

It usually pulls through it, but I doubt this is your case with that much pressure and probably a small cam.