Referred to as "burping" the coolant system. It's also important to be aware that the coolant temp "sender" to gauge, & the Electronic Cooolant Temp "Sensor" (ECT) that communicates w/ the ECU are separate & not related to each other in function.

Self diagnostics almost a mute point until he deals w/ the missing o2 sensor. W/o it, 10 mpg is the best you can expect. ECU is most likely operation in fail safe mode.

 

agreed....

there is no reason that a 302 or 300 cant get at least 18mpg empty...

Mine does very well unless I am just plain beating on it... My bud has a 302 extended cab 4x4 all stock and he gets darn near the same mileage I do... only exception is his is OBD-I MAF..... all stock and it hasnt been tuned up in forever...lol

 

I'm currently getting 17mpg highway (302/AT), only because I'm overdue for a plug change (Side gapped copper cores).

 

Before the headgasket change i was only getting 150 to my front tank too. Which is about 11 mpg.

 

I never swapped engines. Pulled the heads and did the gaskets.

 

I deleted that post after reviewing OP. I'm posting on an engine swap thread also.

 

It's cool lol. I did all new copper core motorcraft plugs 8mm wires and house brand cap n rotor. I have Headman long tube headers. Dunno why i only get 11 mpg on the interstate

 

We told you. No O2 sensor. How do you think the ECU can adjust fuel trim w/o that input?

 

I understand. I'm saying before i took it all apart and took out the o2 sensor i wad getting 11 mpg and no check engine lights not any codes

 

Hell my 302 gets like 7 or 8 mpg its awful