Missing at High RPM

[Trance_LT4]

I've got a miss under WOT that starts around 5000 and higher, slightly lower in 4th and 5th.

I know that this could be detonation, or my knock sensor getting a false reading pulling timing away. My question is about the other posibilities, like fuel starvation (doubtful), dirty injectors, optispark (which has been changed once) plugs wires?

I'm at a loss, and I don't feel like throwing cash at it until it goes away. Will most shops be able to diagnose this without just fixing stuff till it works right?

 

[6shark9]

I've had Sm Block Chevys act like this when the timing chain jumps a "tooth". But never in anything under 70,000 miles.
(And all pre '80 motors)

 

[Trance_LT4]

Hit 72000 last week or so

 

[Tuna]

Have you change the fuel filter yet? That's what it sounds like to me.
The LT4 really likes a good supply of fuel in the higher RPM range and an old fuel filter with some trash can slow the flow down enough for the LT4 to let you know.

Besides changing the filter, the only other way to check it is to install a fuel pressure guage and see what it does as you take it up through the gears.

Hope this helps

 

[sothpaw]

I would agree about the fuel filter. How long has this been going on?

 

[CKA_Racing]

Pull the plugs and make sure they still have the little puck. Losing the puck changes the gap to around .60
Still have the stock type plugs?
Check them even though you may have recently installed new ones.

 

[CKA_Racing]

If you are tight on money or don't know how, come to my house. I'll check them for you.