civicracer1993

i have a dx bottom end with a 89 si top half in my 93 hatch. i had this motor in my crx before and the same prob was happening, when i first start it up its fine about ten minutes or so till its fully warmed up then its starts to idle higher and it will stumble when i first hit the gas to go. and it doesnt run as good. any idea what this could be? its done it in both cars i had. timing is good. ??

Perfectionist

When cold, the ECU will rely on a base fuel map. When the engine warms up, the ECU will trim the fuel based on various sensor inputs. It might be seeing something from a sensor it doesn't like. Check out the TW, O2, TPS, FIV, etc, for starters.

Or, could be a vacuum leak from either a gasket or a ported vacuum system. Spray a mist of water around all mounting flanges. Visually inspect vacuum hoses.

civicracer1993

is there any way to keep the ecu to stay in that mode so it wont rely on the sensors?