What Happens At 4k RPM?

[rico05]

All of my bucking, popping, surging problems happen below 3800-4k RPM. After that, I can hammer it and it just spools and goes. What changes about the engine mgmt. or the engine itself at 4k RPM?

[boost_boy]

Cold start valve, spark plugs, possible leak (I highly doubt that). So many little things that can cause you to have issues, but these are the ones I can think of immeditely.

Dee

[rico05]

Tell me more about the cold start valve.

Update: I fiddled with the timing again (retarded it a bit) and found that many of my problems are lessened or have gone (only when warm though).