You guys. My husband has a 96 F150 5.0L. Sometimes it runs fine, but often it has two problems. One, when you're going fast, like on the ramp getting on the highway, it will start to shake, and I mean SHAKE like the world is coming to an end. Slow down and the shake goes away. The mechanic did some sort of half-a** "balancing" job but did not fix it.

The second problem: sometimes while you're out driving, it just starts to run like crap. Speed does not matter. Yesterday driving home it started to run really rough all of a sudden, and it stalled out in our driveway. This morning, it's running fine again. It's been to a mechanic for this too, and he said something about a possible misfire.

Has anyone else had this sort of problem? Is the shaking related to the running poorly? When it was running bad yesterday it smelled terrible, but not like oil or antifreeze or fuel. Like...burning plastic or rubber.

I work at Blackstone Labs and the oil analysis doesn't show anything unusual. No fuel in the oil, no poorly wearing parts. I swear to god though, I'm ready to drive this truck into the river!

 

Check motor/trans mounts and clean the MAF sensor. It also may have a crappy coil, which I would replace with the MSD street fire.

 

Has anyone checked to see if there are any ecm codes set?

 

I would say your shaking problem could be one of a couple things. Broken belt in a tire, bad allignment, or needing some front end work (bushings and such).

As for the running poorly... does the "engine" light come on? Is the computer throwing codes? running rough and stalling can be too many things to count... So I usually start with the basics... Does it have good spark? spark plugs done how long ago? hows the cap and rotor? I've had stall problems when the under side of the cap gets wet. could be any one number of sensors... again need to check the computer for codes. (free at O'reillys if you ask nicely). we could all conjecture about possibilities but we really need more info...

 

The tires were new last summer; they've got maybe 5,000 miles on them. But our office is right next to a Tire Barn so I will take it in there next week to have it aligned. If it was a tire/alignment problem though, wouldn't it happen every time we went fast?

The spark plugs & wires were done last summer too, when we first started having the rough running problem. I will call Brad and ask him about the codes. The mechanic we're taking it to is actually pretty good. Ford trucks are his specialty--I assume he would follow up on what the codes were telling him (but you know what happens when you assume!).

If a cylinder was misfiring, would it cause both of these problems? Wouldn't I end up with fuel in the oil? And why the horrible smell? It's so frustrating because both these problems are so intermittent.

 

You will only get fuel in the oil if you have blow by due to bad rings or cylinder wall scoring.

 

I think that one of your sensors, actuators, TFI modual, or distributor PIP circuit is getting hot and messing up, and could also be the computer, when hot screws up...no easy fix, check the codes, begin eliminating each with a decent repair manual. Haynes is good with its walk throughs.

 

Do the problems happen at the same time? If they don't happen at the same time I wouldn't consider them to be related.

Back to the shake...

Is it small or big shake... a mis-balanced tire or broken tire belt would cause a shake once a certain speed is exceeded. Bad alignment would cause the truck to vere hard one way or the other when you take your hands off the wheel.

I would rotate the tires and see if the shake follows the tires to the rear of the vehicle... if not then you can rule out a bad tire (bad tires do happen from time to time).

Also check your front ball joints and universal joints. Check the ball joints by jacking up a front tire just a little off the ground and then stick a pry bar under the tire and try to push it up and down. if the tire goes up and down a decent amount you have bad ball joints. Bad ujoints will also cause a really good shake once they are bad enough... trust me on this one...'


Also check motor mounts... Does the shake come thru the floor, steering wheel or both? front or back of vehicle shake?

 

Thanks for the help. The shake comes through the steering wheel and is in the front. It's so bad it's hard to hang on to the steering wheel when it happens. The entire truck shakes back and forth rapidly.

 

forget the tires and alignment then and go strait to the u joints/ball joints and drive line to find the problem.

 

The shake is in the steering wheel , so thats the front end , look for anything loose like tie rod ends , have someone move the steering wheel back and fourth and get under the truck an see if any thing is loose....If it was in the drive train you would feel it in the seat....Lew