3.0 swap

[plasticsaint]

I've got a '99 3.0 ranger that I revently replaced my blown 3.0 with another used 3.0. Now that I've made the swap, my gas mileage is all over the place and my oil pressure doesn't register at all until the motor warms up. Any clues on what the problems could be??

[plasticsaint]

oh and the old motor was a flex fuel model...the new one isn't. Could that give me problems?...and if so, why? Thanx!

[Wicked_Sludge]

you re-used your FFV PCM didnt you?

FFV's use a completely different PCM than the non-FFV trucks.

[Mutant Pony]

Did you change the injectors/fuel rail to the one that came on the truck? As long as you use ALL of the fuel system you should be fine.
On the oil pressure, You may have damaged the sender during the swap. You may also have a damaged or broken body ground.