A few months ago i bought a 92 f150 4x4. Since purchasing the truck i have noticed a few things that sort of bug me with it's performance. First of all, after putting plugs, wires, air/fuel filters, cap/rotor the thing runs like its nobody's business but i am still experiencing a rough idle. I have thought about adjusting the timing but it is factory preset. Secondly, is 13 mpg about the best i can do out of 351w/E4od/ 3.55 ls, or should i expect more and where can i get it? Also were there different variations for the 351w when it comes to horsepower and torque? The reason i ask is that a friend of mine has virtually( minus paint and trim package) the same truck, just a couple of months newer and mine will out pull and run his any day and he has less miles on his. I have already defeated the thought that the previous owner has done any modification to the truck because he bought it new in 92 and told me he has not done anything to it besides basic maintenance. Lastly my front axle will not engage. I think it maybe the automatic hubs are not locking in. Can i replace them with manual hubs and bypass all of the components necessary for the auto's? Any and all advice will be appreciated. By the way the truck has 196000 miles on it with all original factory equipment

 

Hi, and welcome!

13mpg is pretty good for a 4x4 with the 351. I doubt you'll get better than that. As for your truck pulling away from your buddy's, and having a rough idle, I wouldn't be surprised if you had performance cam in that engine. It having close to 200k on it, it would not be surprising to find that there has been some engine work done.

As for the hubs, you certainly can swap them out for manuals (you'll need the bearing nut tool). I just hope that's the only reason for the problem...

Let's see pics of that truck!

 

I've got a 95 with the same set-up. Over the years the hp and torque on those 351's creeped up. By 95 it had 210hp and 325 lb-ft of torque. It pulls on alot of trucks from the same era. I had the same problem with my front hubs, and I just had a shop throw in Warn Premier manual hubs while I was at work one day. As far as gas mileage. My best was 14mpg, but now it's about 12.5 with 110k on it. But the thing is, I get 12.5 no matter what. City, highway, pulling, towing, offroading (as long as I keep it out of 4Lo). Just the way these trucks were made I guess.

 

Search IAC for a rough idle and pull yer codes. www.fordfuelinjection.com can tell ya how.

13 is purdy dang good! My style of driving gets a lot less. Remember yer a heavy unaerodynamic rollin' brick.

Adrianspeeder

 

I appreciate all of your help so far. another problem that i have concerns one of the hard plastic vaccum lines under the hood. I broke all of them on the passenger side of the motor while changing out the plugs ( damn they are brittle) i have replaced all of them except the pink one. I referenced the diagram on the hood but i cant decode the shorthand script to tell where it goes. All i can tell is that it goes somewhere on the front top pass side of the motor, maybe the emissions pump, but i cant find where to put it.

here she is in all of her glory. oxidized paint and all. Little rust above the rear wheels, other than that its pretty straight. Not bad for $900 if you ask me!