RB26 surge problem

[tommyboy]

I took out my engine to replace the bearing and I replaced the stock intake with a bigger one, now when I try to start the engine it barely starts then when it does it revs to about 3000rpm then drops down to 1000rpm. It’s getting fuel and all the vacuum hoses are connected, I’m running the stock ecu does it need a tune to get it running I can’t seem to figure it out.

[Skym]

Check for intake airleaks behind AFM's. Sometimes not tightening intake hose clamps enough can cause hard starting. Should tighten intake hose clamps until you can't turn them anymore. Some stock style intake hose clamps are use once or twice only (replace them with stronger bolt style intake hose clamps, multi ply silicon intake hose joiners and tighten them properly, especially when boost levels are raised above stock).

Sometimes throttle body cable is not adjusted correctly (allowing too much air in) or throttlebodies need cleaning (avoiding using cleaner that damages the throttle plate shaft seals and avoid going near them if possible with cleaner).

[tommyboy]

I have a hard pipe kit I've checked all intake pipes and I backed the cable off then made ajustments and its still surges

[NerdJuice]

When I had a surging problem it turned out to be my intake manifold gasket, like the one between the coolant lines and the head.

Also check for leaking throttle plates (spray with carb cleaner, if leaking RPM will rise), and possibly your IAC valve.