I am having a major problem with a 1993 F150 that I just got. I don't know the history on it, but it pretty much dies out or bogs down the harder I press the gas. If I shift to low gears, it does a little better but still does the same thing. There is a loud popping noise too. The harder I press the gas, the more it pops. It sounded like it was coming from the front driver's side wheel, or suspension. I opened the hood and watched the engine compartment as I reved the gas just to see if I could see anything going on. Apparently, the lid of the air filter was not screwed on because the lid popped up every time I heard the popping noise. I did screw it back on the best I could but you can still see it jumping a little bit when the gas is pressed. Any ideas of what's up with this?

Oh, and I did change the fuel filter. It didn't help...

 

Is the spark plug wires ran right? How longs it been setting?

 

More than likely with a truck that old you have a burnt intake valve. That's why the air filter cap is jumping around as air is coming back into it from the engine. That's also the noise you hear. It COULD be a stuck valve as well. If the truck sat for any length of time it can certainly happen. The first thing I would do is go to the cheapest auto parts/walmart and pickup 5 qts of the cheapest 5w-20 oil you can find and change the filter too. Start the engine and let it idle until it reachs operating temp. Then start with the idle at 2000 rpms and if it starts popping, let it idle at 700 rpms again for another 10 minutes and do this until it either clears, which should be in the first 30 minutes, or you give up. The thinner oil will clean as well as get into places the normal 5w-30 won't. If it is a stuck valve, that should clear it. Then change back to a normal 5w-30 oil or for that engine you could run Rotella T 5w-40 or the 15w-40. Rotella is a dual rated for gas and diesel engines. It packs more cleaning agents in the formulation. Hopefully it's nothing more than a stuck valve but I wouldn't suggest driving it until you get it fixed. damage is occurring with every spark of the plug at the seat and at the valve. It'll also screw the cats. But make sure to check the firing order too.

 

I wouldn't run thin oil in an engine that old. I'd start with the timing: follow the instructions printed on the VECI label under the hood.

WHAT ENGINE does it have? If it's a V8, read these:
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Then I'd check fuel pressure with a gauge and maybe change the filter. Then compression, vacuum (for exhaust restriction), & valve timing (timing chain slack).

. . .

 

possibly a bad mass air meter?..

 

I was thinking it might be a cam lobe, (exhaust).

Kind of hard to tell by your description, but when the cylinder fires, and the exhaust valve doesn't let the exhaust out, (because the lobe that opens the exhaust valve is gone) it'll come out the intake valve (and out the air-cleaner) on the intake stroke.

 

x-2 on timing and when was the last time you did a tune up and i would also do a compression check these would be a good starting point and then expand your trouble shooting as required

 

You're still thinking viscosity and not film strength. I've been using a 5w- 20 in a modded 391 for years. No issues with wear metals at all and this engine gets abused more than any of the others. But not knowing the mileage on the unit makes for some grey area which is why I stated to run it- no load, as in not to drive it, just run it. And as soon as it turns the valve loose, change the oil. It's a dose of penetrating oil if you want to look at it that way. And it's also a great way to flush sludge out of an engine that has been sitting.
I'd just about bet the ranch that in 10 years or less, you'll be looking back at the days when we ran the real thick oils, like the 5w-20 oils. There's a ton of technology going to be hitting the streets and soon with oil viscosities at 0w-0 and thinner that won't kill an engine but actually add life to it and yield significant fuel mileage benefits.

 

Not even optional in '93.Maybe... But I can guarantee you that I won't be driving an engine designed for 10W-40 or 20W-50 when I look back. For now, this is what I'll use for every vehicle listed in it: