Hi all,

I've had my truck for a couple months now and have put around 1,000 miles on it. A couple of issues have come up that I'm hoping someone can help me with.

It's a 1995 F-150 4wd, standard cab short bed, 5.0L, 4 speed automatic (not sure which one), 3.55 limited-slip rear axle with 32x10.50-15 tires. Total vehicle mileage is 124,XXX.

1. My mileage isn't quite what I was hoping. Highway is 13 mpg, running errands in the country and in town combined is 10-11 mpg. I don't expect much, but it's supposed to be in the high teens on the highway per my research. Is there any way to improve the gas mileage? Would dropping down to 31x10.50-15 improve the mileage much? The sticker says the stock size was 235/75R15, but that seems awfully small.

2. The transmission shudders in 3rd gear. There is a shudder in the whole truck lasting about 1.5 seconds that occurs regularly every 6-8 seconds and feels something like driving over those rumble strips they have in the road before a stop sign. It's stronger at lower speeds (30-40 mph) when the engine is under load and is almost undetectable when coasting. At highway speeds (55~ mph) when the transmission downshifts to 3rd gear (either manually downshifted or automatically going up a hill) the shudder is still present, but isn't near as bad as it is in the 30 mph range. There is no loss in power when it shudders and the fluid is full.

It's important to note that prior to my buying the truck it had been parked and not driven for 4-5 years after the previous owner died. I have changed the oil and fuel filter, but haven't changed transmission filter or fluid.

Any ideas?

 

Sounds like it's just not running right. Have you cleaned the air meter? 95 has mas air flow meter right? Have you checked alignment? Spark plugs, ignition in general? Really running @ 55mph? Stock tires are right, 32's are big. Not vice versa.

 

I don't see how it would be the engine, it runs fine in 1st, 2nd and 4th gears. It's only when it's in 3rd gear (either by the transmission's own selection or by my turning off the overdrive) that it shudders and there's no loss in power; in what way could the engine be at fault? The shuddering at 30-40 mph goes away if I shift down to 2nd, so it wouldn't be the tire or driveline balance. The ignition is in good shape, the engine doesn't miss at all and the spark plugs are clean and gapped appropriately. It does have a MAF sensor, I don't know how to check it but the check engine light isn't on.

As for the speed, the difference between GPS speed and speedometer speed is negligible (2-3%) and the odometer is off the same amount as measured on the freeway by milepost. I know that 235/75/R15 is the correct stock tire, it just seems a little small for the truck in terms of looks is all I'm saying.

 

i was focused more on the mileage than the shudder. it's hard to diagnose over the internet.

could be an issue in the trans, but i'm not an automatic trans tech.

sorry no one else has chimed in on this.

 

Gotcha. How would I go about cleaning the MAF sensor? Spray carb cleaner on the wire (I think it's a wire, although I haven't gone out and looked yet).

 

Cleaning the MAF probably won't make a difference. How new are the ignitions parts? A tune up and a timing pump might help a bit. Is it dual tanks? If so do they both work? Does the truck smell of raw fuel while running?

As for the trans, it is computer controlled whether it be an E4OD or the 4R70. If it's an E4OD the door sticker will have an "E" for the trans code, "U" if it's the 4R70. Try pulling codes to see if any trans related codes.

 

Everything is at least 5 years old (that's how long the truck sat before mid-August), but the cap and rotor are clean and dry without excess carbon buildup. I'm not sure what you mean by "timing pump"? Single tank, truck doesn't smell of raw fuel.

A friend of mine pulled codes (OBD-1) and there were none. If there were a transmission code the "OD Off" light on the shifter would flash, right?

 

On a stock truck with a 302, I would not use any larger than 31 x 10.50 tires. The engine doesn't make enough low end torque. The truck will do best with stock 235 75 15 or 30 x 9.50 tires.

 

Yeah, I noticed it doesn't have a whole lot of power for a V-8 and a light truck. I was going to go 31x10.50, but I think I'll go for 30x9.50. It'll give it a lot less contact area friction to overcome too.

 

He probably meant "timing bump." You could try the six liter tune up, just google it.

It could have a trans code without the OD light flashing.