Hello H-T I have a 90 crx dx with a b18a1 swap. It has I/H/E I just did a head gasket and swapped to the 96 b18b1 since my old head was going out. The car runs great the only problem im having is really bad mpg am getting around 70-80 miles on half a tank. When I use to get around 130-140 on half a tank. I have replaced o2 sensor, Fuel filter, Air filter, new dizzy, spark plugs, and nothing has changed. I do have the CEL on check ecu for codes only code am getting is code 6 Coolant Temperature. Don’t know what else it could be im going to swap out injectors again. Other then that I don’t know what else it could be.
Any help greatly appreciated

 

a faulty coolant temperature sensor can cause the computer to believe it's cold therefore dumping more fuel.

 

Wow... why wouldn't you fix a CEL if you have one? Are you serious about this thread? Obviously if you have a CEL you are running in OPEN loop!!! Clearly the ECU runs the engine rich when in Open loop as a safety net... Also - the coolant temperature sensor being bad you make your gas mileage suffer pretty bad as well as runability problems.

Also on a side note - since I am mildly on topic; Most of the time (I said MOST not ALWAYS) when an engine is overheated the coolant temperature sensor fails and sometimes the temperature sending unit too...