missing problem - upper rpms

[THEDUKE]

I have this missing problem in the upper rpms. This happens when I ajust the fuel. If I go leaner or richer. There is only one point in the fuel mix that it will run & not miss.All my ignition is redone with msd wires,NGK plugs,New coilpack,MSD II box.I have had this problem with these injectors I am running.They are MSD 630 I can reemove them & the problem goes away.I only have the 450 to replace them with. When I get it where it dont miss with the 630 Knock,timing,o2,pulswith all look good. Could these injectors have a deadtime that will bairly work with the DSM.I bought them used & dont realy now what they are for. What brand & size would be good for my setup.I have been told that the 720 - 780 is about as big as I can use with the afc. I have the SAFC & a translator with 3 1/2 GM maf. It shows in the translator ajustments up to maybe 1100cc injectors. I know I will need big injectors later but could get by with the 720-780 for now.Does this sound like the injectors may be my problem & what brand to buy if it is.

 

[hostile]

You dont want injectors that big with an afc. Also it really depends on your turbo.

Have you checked you base timing lately? The only reason i can think of it missing with injectors swapped is, because when you put the 450's back in the stock airflow maps are being used. But with the larger injectors you clip the airflow and it changes your tinming maps giving you more advance. You might be getting too much timing advance and what you feel as a miss is the ecu pulling your timing due to knock.

The only other reason for a high rpm miss would be blow out, are the plugs gapped a .028?

 

[efeezie]

checked for boost leaks yet?