I got 96 lt1 rebuilt le 228/236 cam 918 springs installed to le spec, long tubes headers, off y pipe ,bullet muffler and pcm for less tune.. shift point is 6300-6400. Rev limiter is 6500.. problem started after I done a alternator relocation. Now it sputters and surge above 5k but most times it's at 5800 to 6100 rpm..
I have changed alot opti, wires, plugs gapped 40, swapped coil, icm, fuel rail, checked fuel pressure soild 43 psi, no codes, nothing on data log, double checked valve lash it's 1/2 turn.. please help.. I'm bout to swap wiring harness make sure nothing is cut or something. .

 

I've seen alternators cause some weird issues. Make sure the Alternator has a good contacts and that it has a good ground contact to the block.

 

Ok.. I will put a ground wire to it.. I put new alternator to.. I forgot that.

 

Checking the ground is a good idea but I would also ask how old are the springs? You know springs are a maintenance item with aftermarket cam right?

 

I bought them in late April maybe 4k miles On them.. how would valve float feel?

 

It would go soft up top and begin missing if you kept trying to rev.

 

It done it few times at 5400 then went flawless to shift. I got video of How it does too.if that help

 

Plug wires arcing around peak torque rpm when cylinder pressure is highest.

 

i redone the gounds and put extra one on. no help... i tried taking the bolt and spacer out at the opti on the alt relocation bracket and unhooked o2 when i was under there. it made full wot pull to 3rd gear. a (little) sputter at 5k.. a friend told me maybe maf is going bad.. thanks for input

 

started doing it again. pluged back up o2s. tried cleaning and unhooked maf.. didnt help.. checked fuel pressure again.. 43 psi soild still. anymore ideas please

 

Not the easiest thing to verify but pretty good bet at this time.

 

what kind u recommend? i have cheap ones so u could be right!

 

Magnacore, Taylor are what many use. put dialectic grease inside opti & plug boots. run as factory did in brackets & looms

if after swapping/checking all the parts you have and still high RPM break-up....the opti is suspect (sensor)

your "economy" plug wires are suspect so as Caprice advises, get a quality set of plug wires

 

i done a alternator relocation so i cant u factory loom

 

Thats ok, just use split loom where the plug wires might touch each other...the whole idea of the factory routing was to keep the wires seperate.

 

could wires touching cause this?

 

Any tuning software or have you done just mail order tuning? Had this problem with our last mail order tune. Rev limiter was supposed to be 6700 and shift points @ 6000. Found the rev @ 5800 and shifts @ 6000. It was sputtering when it hit the fuel cuts, sounds similiar to your problem.

 

Mail order.. I tried my old computer with cc305 does it to.. also car run great till I put relocation bracket on. Wires lay on top alternator. . Wondering if that cause a problem

 

It certainly can, try re-routing them away from the Alternator, or at least make sure they are about 1-2" away from it.

 

Im running the relocated alternator as well and they come up around it in the holders with no issue at all, seems to be plenty of room. If thats all you changed and now you have a problem, must be some wire/alt interference.