Gone to the dark side here and replaced my old chevy with a 1992 ford f150 ext cab short box 4x4 302, e40d approx 130k miles 33x12.5x15 tires and a bit of a lift.

Got it for the right price and been fixing a lot of the little stuff that the previous owner took apart and never put back together or never knew how to fix in the first place and have it to where it can be used and driven now.

Would like opinions about which component(s) to attack next to see if we can get the mileage up over that 8mpg mark driving highway on fairly straight and level 60mph. I have my suspicions but some of the real ford enthusiasts might be able to provide some direction. Going to eventually go through it all but getting the fuel mileage up higher would help most in the short term.

So the problems I can identify that might affect the mileage can best be described as follows.

EGR valve is bad - error code 332 in the computer - verified it was not working by hooking up vacuum at an idle with no change in rpm - purchased part and will replace next weekend. On a GM it would likely throw the computer into a limp home mode and be not efficient and could explain the problems. Not sure if Ford reacts that way or not.

33 inch tires - is it possible that the 302 with this transmission just doesn't quite have the punch to run that large of a tire or shift points are not going to be quite right to power through it? Calibrated the speedo so it is showing the correct speed with the larger tires.. kudos to ford for that easy fix.. not sure how much the taller tires would affect power or MPG

Possible partial clogging of the cat converter? Temp gauge runs about the right hand side of the M in normal. Thinking it could have a restriction due to a perceived lack of power. I can scoot down the road at 70 but seems like I have my foot into it more than I should need. Cruise will not hold speed on slight inclines unless I turn the overdrive off but with overdrive off it will. With the age/mileage on the rig a clogged converter comes to mind as it looks like it is probably the original.

Fuel pressure could cause the lack of power but thinking it would not as likely cause the poor mileage.

It starts and runs great.. smooth with even acceleration. And no.. have not done a complete tune up on it yet.. still fixing all the known bad/broken/wore out components before fine tuning. Kind of last minute emergency vehicle change since someone ripped off my other truck and with winter on my heels and working in a driveway am looking for the most likely biggest bang for the buck checks and repairs to hopefully get it through till spring when I can dig into it deeper.

Thoughts and suggestions? Tried to describe any and all pertinent symptoms and observations here to help hone in on the most likely culprit.

And here is my first use of a ford smilie... welcome to the dark side.. i heard you have cookies!

 

Is your speedo calibrated for the tire size difference? I bet not...that should net you a mpg, maybe less, corrected.

Your gearing prob isn't good for the 302 stock, much less with 33s. Don't expect huge gains from a gear change, just a little more pep.

Unfortunately you shouldn't expect much. If those 33 s are mud terrains that'd explain some of it also. You could pull codes, see if anything shows up. A malfunction in the emissions system will indeed decrease mileage, and cause poor drivability. Don't expect miraculous increases in mpg even if you find a problem, you'll likely never see north of 11ish.

I always got 9-10 no matter how I drove with the 302. Granted, I have 3/4 ton running gear but i also had a 5 spd and long tubes. The 302 is a poor example of what should be in a truck. It's a struggler, which is never good for mpg.

Edit: I breezed through your post. Yea you need to fix the egr. It could be the valve itself, the sensor on top, or a break in the vac line(s). Go buy yourself a vac tester if you don't have one already. You can confirm the egr is bad by hooking it to the port on the valve, apply vac, and see if it holds it. If it doesnt, obviously it's the diaphragm in the valve that's bad. If It does Hold vac, move on to testing the vac lines. All that checks out, there are tests for the other components.

 

Give it a good tune up. Coil, Cap-Rotor, Plugs, wires, O2 Sensor, check-fix all vacuum lines, check-fix all exhaust leaks before the 02 Sensor, ACT Sensor, advance the timing on the distributor, Check Throttle Position Voltage-adjust-replace if needed.

Other then that, the previous person that posted is correct. The 33's are killing the gas mileage in my opinion. Replace with stock 235.75R15's and you should get at least 13-15 mpg highway with a well tuned engine.

The stock 5.0L will always lug up hills....Even with mods such as intake, full exhaust, pulleys...It is just not a enough displacement and or stroke for a big truck. You will need 4.10 gear ratio or higher with those big tires.

The only thing you should worry about is that transmission.....If not done, "get a better Transmission Auxiliary oil cooler." The E4od is computer controlled and likes to be kept cool.

Welcome to the forums.

 

Thanks for the thoughts.. lol.. maybe i put too much jibber jabber in the original post but have tried to do due diligence and include info.. already recalibrated the speedo and reads dead on at 60.. hooked vacuum directly to the egr at an idle with no diff.. only code in the computer is 332.. so already got a new egr then will be able to test the rest of that system.

Using the vin decoder looks like rear is 3.08 ratio and though I love the look of those 33's sounds like gonna have to go smaller. What you think about a 31/10.50/15 that is my favorite go to tire size.. think it would handle those without much of a power/performance loss? Hate to think of stock size on it as with the lift would look so out of place.

Good point on the tranny cooler.. always heard these could be tore up so will stuff an aux cooler on it.

Don't have a good way of testing the cat converter short of running open headers as it looks like it has two under there with the first coming right off the exhaust manifold.. might be a little too loud to do a good test of mileage and power.

 

The 302 in my '89 F150 5sp w stock size tires (150K miles) gets a steady 14-15mpg and my '94 Bronco 302/E4OD (217K miles) got 15-16 on 31's.

As mentioned fix the egr do a tune up including the fuel filter.

 

Think what I will do is fix the egr monday then take her for a little road trip to see how much/if it effects mileage much.. maybe run it to the wrecking yard and grab an old set of wheels n tires then test with stock size. Will update with results.

 

Can try cruising with the overdrive off to bring the revs up. Won't do anything in town but on the highway it will act like a better set of gears

 

With the setup you have now, Overdrive is useless. I hardly even use it and I have a 302, bored 0.40 over, different cam, 1.7 roller rockers, MAF conversion, timing bumped to 15°.

Tires and gearing hurt.

I would keep it out of OD period even with 31x10.5 tires. That's what I have and 3.55 gearing. Unless your driving 80mph, 3k in rpms is just making power AND you will probably see a mpg increase.

 

I thought about running with the overdrive off but that little voice in the back of my mind kept telling me that overdrive=good.. lol.. if I get a chance will try with the larger tires both with overdrive off and on and compare. Not sure I will have that much driving to do in order to do a valid test.

 

With the 3.08s and 33s, you should turn about the same rpms @60 in drive that I do in overdrive with 31s and 3.55s.

 

What gearing does the truck have? If it has 3.08 they yeah you need to completely forget the trans has an OD ratio.. it not useable, this motor needs 4.10 gears minimum to pull 33s in OD. And as discussed elsewhere lugging this motor is counter productive, it make no useable torque below 2000rpm so hwy cruise rpms should never be below that unless you travel mostly level ground at relatively slow speeds(60mph). If you want to travel faster then top gear rpms should be 2000-2500rpm and believe it or not that will deliver dramatically better fuel milage.

 

Well I found one major culprit in my fuel mileage problem.. The front fuel tank was leaking, I suspect around the sending unit but have not had a chance to confirm. So I had run the fuel out of it and was running on the back. Guess what.. my front tank filled back up and started leaking again. So unless the gas fairy filled my tank I have a bad check valve and the rear is pumping into the front.

Guessing it probably ran 7 or 8 gallons to the front in the course of probably 2 or 3 hundred miles. Gonna see about fixing that and test it out.

EGR valve replaced but still the idiot light. Now when I hit the valve with vacuum it stalls the engine but there isn't any vacuum to the coffee can so will look at tracking it back to its source.

Looks like one of my next tasks next couple of days will be to find and fix that check valve and see what the mileage comes to after that.

 

EGR Fixed.. fuel tank gonna have to wait a week. While wandering the pull and save lot I ran across a gnarly old steel bumper on the front of an old dodge that is going to have to come home with me tomorrow.

By the way.. someone should hunt the guy down who thought those little plastic vacuum lines were a good idea and shoot him. One of the long term fixes is going to be to replace those with soft rubber ones.

 

Next person to hunt down is the guy who thought it was a good idea to run that EGR tube under the intake. Apparently someone had spliced it with a rubber hose and after running it about 10 miles that rubber hose blew and now I need to repair or replace the EGR tube... which appears to require removing the intake. Going to experiment a little bit and see if I can patch it without removing it but will see. Thinking I might get a short piece of copper tubing that fits inside the existing pipe and glue it in with high temp rtv silicone. Will see if that works out or not.

 

Removing the upper plenum isn't nearly as bad as it looks.