New motor, rough idle- runs better warm than.......

Hey all-
Just fired up my fresh motor- solid fuel pressure + oil pressure. When I fire it cold, RPMs jump and dies- runs better when warmed up? I pulled the codes thrown, which directed me to the MAP sensor- would that cause this to run like SH*T? The MAP is old, so I will replace that and see where that puts me- any additional ideas out there? 9.94 to 1 compression, TPIS Mini-Ram, 58mm TB, SLP 1 3/4 headers, 24lb injectors, MSD coil, 6A, billet distributor, coil. Any ideas, please feel free to share! Thanks in advance! :confused: :confused: :confused:

When I fire it cold, RPMs jump and dies- runs better when warmed up? I pulled the codes thrown, which directed me to the MAP sensor- would that cause this to run like SH*T? RPM jumps? up and down? Yeh, the MAP could make it lean, and run worse cold. Re-check timing? advance a little?

The MAP sensor is more of an influence on the fuel mixture when the engine is cold. When warm, the O2 sensor kicks in and takes over the bulk of the load. If you are getting the code, then the MAP is at least part of the problem.

Unless the O2 sensor is a wideband, it can't make as large corrections as the MAP, and before I'd scrap the MAP, I'd check my Vacuum reading. A large cam can cause a MAP code from a reduced idle vacuum signal.

Replaced the MAP sensor and the car now idles great, no codes. Much better throttle response. Amazing how large an influence that little sensor has!! Thanks once again for the input everyone! :cool: