300 I6
 

i have a problem with my 89 f150 300 I6 with a c6 tranny i am getting about 12 mpg highway driving i have changed fuel filter done a whole tune up set the timing every thing but still the crappy millage

next thing venture effect tubes what are they were are they located and will they help in my application

next the intake snorkle, i saw a discussion on it and was considering it my self, but what about the snow i live in michigan and take my truck through allot i don't want the snow or rain to screw it up

thanks for any help with any of these questions

300 I6
 

I had the same problem with my '89' 460 F250. I change three sensors and now get 12.5 MPG which is fairly good for Fords' big block (I was getting 8-9 MPG). I would replace the ACT (air charge temperature) sensor first. It determines air-fuel ratios. Next I'd replace the ECT (engine coolant temperature) sensor. It also determines air-fuel ratio and spark timing, in fact Charles Probsts' book on "Ford Fuel Injection & Electronic Engine Control" says this sensor is one of the most important in determining engine speed and load. Those two sensors will cost you about $40. if you install them your self. The next sensor to replace would be the O-2 sensor, it fine-tunes your air-fuel ratio but is not as critical to fuel milage as the "ACT" and the ECT". Two other things you should check is engine compression and take your truck to a muffler shop and have the catalytic converter checked to see if it's plugged up. Let me know what you find. Deen

300 I6
 

Venturi Tubes - you probably don't have them. They seem to be only on the larger motors. I have a '93 with the 300 and I don't have them. If you did, they are located in the tubes running from the airbox to the intake.

Snorkel - 4Wheeler did an article in a recent issue for the project MPG series. One of the more interesting tests was that they removed the snorkel all together. The mileage actually got worse. I don't know about cutting or redirecting the snorkel. Personally, I'm a bit afraid to do this. It would seem that with snow, anything that got sucked up the snorkel would evaporate, but I'd rather not chance it. You would think there would have been a reason why the snorkel was designed with that little bend at the end.

I did do the reflective tape wrap of the snorkel, airbox and tubes. I'm not sure if mileage has improved much, as I did not keep records prior to the tape. Looks pretty cool, though, and it cost me only $10 and some time.

Change those sensors and maybe look into a K/N filter...

300 I6
 

and the pisser is i drove it this summer to florida and was geting 21.5 mpg highway it just like craped out on me

300 I6